View Filing Data

Print Document View Excel Document

Document And Entity Information - USD ($) $ in Billions	12 Months Ended
Document And Entity Information - USD ($) $ in Billions	Dec. 31, 2017	Feb. 14, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Entity Registrant Name	WESTLAKE CHEMICAL CORP
Entity Central Index Key	0001262823
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		129,419,805
Entity Public Float			$ 2.4

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 1,531	$ 459
Accounts receivable, net	1,001	939
Inventories	900	801
Prepaid expenses and other current assets	30	48
Restricted cash	1	161
Total current assets	3,463	2,408
Property, plant and equipment, net	6,412	6,420
Goodwill	1,012	947
Customer relationships, net	616	611
Other intangible assets, net	161	176
Other assets, net	412	328
Total assets	12,076	10,890
Current liabilities
Accounts payable	600	496
Accrued liabilities	657	538
Current portion of long-term debt, net	710	0
Term loan	0	149
Total current liabilities	1,967	1,183
Long-term debt, net	3,127	3,679
Deferred income taxes	1,111	1,650
Pension and other post-retirement benefits	344	365
Other liabilities	158	121
Total liabilities	6,707	6,998
Stockholders' equity
Preferred stock, $0.01 par value, 50,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.01 par value, 300,000,000 shares authorized; 134,651,380 and 134,651,380 shares issued at December 31, 2017 and 2016, respectively	1	1
Common stock, held in treasury, at cost; 5,232,875 and 5,726,377 shares at December 31, 2017 and 2016, respectively	(302)	(319)
Additional paid-in capital	555	551
Retained earnings	4,613	3,412
Accumulated other comprehensive loss	7	(121)
Total Westlake Chemical Corporation stockholders' equity	4,874	3,524
Noncontrolling interests	495	368
Total equity	5,369	3,892
Total liabilities and equity	$ 12,076	$ 10,890

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	134,651,380	134,651,380
Common stock, held in treasury	5,232,875	5,726,377

Consolidated Statements Of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 8,041	$ 5,076	$ 4,463
Cost of sales	6,272	4,095	3,278
Gross profit	1,769	981	1,185
Selling, general and administrative expenses	399	258	218
Amortization of intangibles	108	38	7
Transaction and integration-related costs	29	104	0
Income from operations	1,233	581	960
Other income (expense)
Interest expense	(159)	(79)	(35)
Other income, net	7	56	38
Income before income taxes	1,081	558	963
Provision for (benefit from) income taxes	(258)	138	298
Net income	1,339	420	665
Net income attributable to noncontrolling interests	35	21	19
Net income attributable to Westlake Chemical Corporation	$ 1,304	$ 399	$ 646
Earnings per common share attributable to Westlake Chemical Corporation:
Basic (in dollars per share)	$ 10.05	$ 3.07	$ 4.88
Diluted (in dollars per share)	$ 10.00	$ 3.06	$ 4.86
Weighted average shares outstanding
Basic (in shares)	129,087,043	129,367,712	131,823,707
Diluted (in shares)	129,540,013	129,974,822	132,301,812
Dividends per common share (in dollars per share)	$ 0.8012	$ 0.7442	$ 0.6930

Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 1,339	$ 420	$ 665
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	19	60	18
Amortization of benefits liability	2	1	3
Income tax provision on pension and other post-retirement benefits liability	(7)	(24)	(6)
Foreign currency translation	124	(34)	(60)
Income tax provision on foreign currency translation	(5)	0	0
Available-for-sale investments
Unrealized holding gains (losses) on investments	0	62	(4)
Reclassification of net realized gains to net income	0	(54)	(4)
Income tax benefit (provision) on available-for-sale investments	0	(3)	3
Other comprehensive income (loss)	133	8	(50)
Comprehensive income	1,472	428	615
Comprehensive income attributable to noncontrolling interests, net of tax of $1, $0 and $0 for 2017, 2016 and 2015, respectively	40	21	19
Comprehensive income attributable to Westlake Chemical Corporation	$ 1,432	$ 407	$ 596

Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Comprehensive income (loss) including portion attributable to noncontrolling interest, tax	$ 1	$ 0	$ 0

Consolidated Statements Of Changes In Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Common Stock, Held In Treasury [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Number of shares, beginning balance at Dec. 31, 2014		134,679,064	1,787,546
Total equity, beginning balance at Dec. 31, 2014	$ 3,202	$ 1	$ (96)	$ 530	$ 2,556	$ (79)	$ 290
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	665				646		19
Other comprehensive income (loss)	(50)					(50)	0
Common stock repurchased, shares			2,701,937
Common stock repurchased	(163)		$ (163)				0
Shares issued—stock- based compensation, shares		(15,820)	(44,585)
Shares issued—stock- based compensation	1	$ 0	$ 1	0
Stock-based compensation, net of tax on stock options exercised	12			12
Dividends declared	(92)				(92)
Distributions to noncontrolling interests	(15)						(15)
Issuance of Westlake Chemical Partners LP common units	2						2
Number of shares, ending balance at Dec. 31, 2015		134,663,244	4,444,898
Total equity, ending balance at Dec. 31, 2015	3,562	$ 1	$ (258)	542	3,110	(129)	296
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	420				399		21
Other comprehensive income (loss)	8					8	0
Common stock repurchased, shares			1,511,109
Common stock repurchased	(67)		$ (67)				0
Shares issued—stock- based compensation, shares		(11,864)	(117,019)
Shares issued—stock- based compensation	8	$ 0	$ 3	5
Stock-based compensation, net of tax on stock options exercised (in shares)			(112,611)
Stock-based compensation, net of tax on stock options exercised	7		$ 3	4
Dividends declared	(97)				(97)
Distributions to noncontrolling interests	(17)						(17)
Issuance of Westlake Chemical Partners LP common units	68						68
Number of shares, ending balance at Dec. 31, 2016		134,651,380	5,726,377
Total equity, ending balance at Dec. 31, 2016	3,892	$ 1	$ (319)	551	3,412	(121)	368
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,339				1,304		35
Other comprehensive income (loss)	133					128	5
Shares issued—stock- based compensation, shares		0	(493,502)
Shares issued—stock- based compensation	$ 11	$ 0	$ 17	(6)
Stock-based compensation, net of tax on stock options exercised (in shares)	(401,505)		0
Stock-based compensation, net of tax on stock options exercised	$ 14		$ 0	14
Dividends declared	(103)				(103)
Distributions to noncontrolling interests	(28)						(28)
Issuance of Westlake Chemical Partners LP common units	111			(4)			115
Number of shares, ending balance at Dec. 31, 2017		134,651,380	5,232,875
Total equity, ending balance at Dec. 31, 2017	$ 5,369	$ 1	$ (302)	$ 555	$ 4,613	$ 7	$ 495

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ 1,339	$ 420	$ 665
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	601	378	246
Stock-based compensation expense	23	14	10
Gains realized on previously held shares of Axiall common stock and from sales of securities	0	(54)	(4)
Gain on acquisition, net of loss on the fair value remeasurement of preexisting equity interest	0	0	(21)
Loss from disposition of property, plant and equipment	22	9	11
Deferred income taxes	(534)	101	40
Other losses, net	(3)	5	6
Changes in operating assets and liabilities, net of effect of business acquisitions
Accounts receivable	(40)	50	63
Inventories	(32)	(62)	99
Prepaid expenses and other current assets	26	11	(4)
Accounts payable	86	12	(22)
Accrued liabilities	115	48	(8)
Other, net	(65)	(98)	(2)
Net cash provided by operating activities	1,538	834	1,079
Cash flows from investing activities
Acquisition of business, net of cash acquired	(13)	(2,438)	16
Additions to property, plant and equipment	(577)	(629)	(491)
Additions to cost method investment	(66)	(17)	0
Proceeds from disposition of equity method investment	0	0	28
Proceeds from sales and maturities of securities	0	663	49
Purchase of securities	0	(138)	(605)
Other	4	(4)	(3)
Net cash used for investing activities	(652)	(2,563)	(1,006)
Cash flows from financing activities
Debt issuance costs	(6)	(36)	0
Dividends paid	(103)	(97)	(92)
Distributions to noncontrolling interests	(28)	(17)	(15)
Proceeds from debt issuance and drawdown of revolver	233	608	53
Net proceeds from issuance of Westlake Chemical Partners LP common units	111	0	0
Proceeds from senior notes issuance	745	1,429	0
Repayment of term loan	(150)	0	0
Restricted cash associated with term loan	154	(154)	0
Repayment of revolver	(550)	(125)	0
Repayment of notes payable	(257)	(13)	(74)
Repurchase of common stock for treasury	0	(67)	(163)
Other	11	5	4
Net cash provided by (used for) financing activities	160	1,533	(287)
Effect of exchange rate changes on cash and cash equivalents	26	(8)	(4)
Net increase (decrease) in cash and cash equivalents	1,072	(204)	(218)
Cash and cash equivalents at beginning of the year	459	663	881
Cash and cash equivalents at end of the year	$ 1,531	$ 459	$ 663

Description Of Business And Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description Of Business And Significant Accounting Policies

Description of Business and Significant Accounting Policies

Description of Business

Westlake Chemical Corporation (the "Company") operates as an integrated global manufacturer and marketer of basic chemicals, vinyls, polymers and building products. These products include some of the most widely used chemicals in the world, which are fundamental to many diverse consumer and industrial markets, including flexible and rigid packaging, automotive products, coatings, residential and commercial construction as well as other durable and non-durable goods. The Company's customers range from large chemical processors and plastics fabricators to small construction contractors, municipalities and supply warehouses primarily throughout North America and Europe. The petrochemical industry is subject to price fluctuations and volatile feedstock pricing typical of a commodity-based industry, the effects of which may not be immediately passed along to customers.

Acquisition of Axiall Corporation

On August 31, 2016, the Company completed the acquisition of Axiall Corporation ("Axiall") for $33.00 per share in an all-cash transaction (the "Merger"), pursuant to the terms of the Agreement and Plan of Merger (the "Merger Agreement"), dated as of June 10, 2016, by and among Westlake, Axiall and Lagoon Merger Sub, Inc., a wholly-owned subsidiary of Westlake (the "Merger Sub"). During the third quarter of 2016, in order to finance a portion of the consideration and related fees and expenses, and for other general corporate purposes, the Company issued $1,450 aggregate principal amount of senior notes. In addition, the Company entered into a $1,000 unsecured revolving credit facility (the "Credit Agreement").

Westlake Chemical Partners LP

In 2014, the Company formed Westlake Chemical Partners LP ("Westlake Partners") to operate, acquire and develop ethylene production facilities and related assets. Westlake Partners' assets consist of a limited partner interest in Westlake Chemical OpCo LP ("OpCo"), as well as the general partner interest in OpCo. OpCo's assets include two ethylene production facilities at the Company's Lake Charles, Louisiana site, one ethylene production facility at the Company's Calvert City, Kentucky site and a 200-mile common carrier ethylene pipeline that runs from Mont Belvieu, Texas to the Company's Longview, Texas site. As of December 31, 2017, the Company held an 81.7% limited partner interest in OpCo and a controlling interest in Westlake Partners. The operations of Westlake Partners are consolidated in the Company's financial statements.

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and subsidiaries in which the Company directly or indirectly owns more than a 50% voting interest and exercises control and, when applicable, entities for which the Company has a controlling financial interest or is the primary beneficiary. Investments in majority-owned companies where the Company does not exercise control and investments in nonconsolidated affiliates (20%-50% owned companies, joint ventures and partnerships) are accounted for using the equity method of accounting. Undistributed earnings from joint ventures included in retained earnings were immaterial as of December 31, 2017. All intercompany transactions and balances are eliminated in consolidation.

Noncontrolling interests represent the direct equity interests held by investors in the Company's consolidated subsidiaries, Westlake Partners and Taiwan Chlorine Industries, Ltd.

Cash and Cash Equivalents

Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition.

Concentration of Credit Risk

Financial instruments which potentially subject the Company to concentration of risk consist principally of trade receivables from customers engaged in manufacturing polyethylene products, polyvinyl chloride ("PVC") products and PVC pipe products. The Company performs periodic credit evaluations of the customers' financial condition and generally does not require collateral. The Company maintains allowances for potential losses.

Allowance for Doubtful Accounts

The determination of the allowance for doubtful accounts is based on estimation of the amount of accounts receivable that the Company believes are unlikely to be collected. Estimating this amount requires analysis of the financial strength of the Company's customers, the use of historical experience, the Company's accounts receivable aged trial balance, and specific collectibility analysis. The allowance for doubtful accounts is reviewed quarterly. Past due balances over 90 days and high risk accounts as determined by the analysis of financial strength of customers are reviewed individually for collectibility.

Inventories

Inventories primarily include product, material and supplies. Inventories are stated at lower of cost or net realizable value. Cost is determined using the first-in, first-out ("FIFO") or average method.

Property, Plant and Equipment

Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects. Capitalized interest was $4, $10 and $10 for the years ended December 31, 2017, 2016 and 2015, respectively. Repair and maintenance costs are charged to operations as incurred. Gains and losses on the disposition or retirement of fixed assets are reflected in the consolidated statement of operations when the assets are sold or retired.

The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract.

Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows:



Classification		Years
Buildings and improvements		40
Plant and equipment		25
Ethylene pipeline		35
Other		3-15

Impairment of Long-Lived Assets

The accounting guidance for the impairment or disposal of long-lived assets requires that the Company review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Long-lived assets assessed for impairment are grouped at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future net undiscounted cash flows expected to be generated by the asset. Assets are considered to be impaired if the carrying amount of an asset exceeds the future undiscounted cash flows. The impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or estimated fair value less costs to sell.

Impairment of Goodwill and Intangible Assets

The accounting guidance requires that goodwill is tested for impairment at least annually, or when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below its carrying value. The Company performed its annual impairment tests for the Olefins and Vinyls segments' goodwill in October 2017 and April 2017, respectively, and the impairment tests indicated that the recorded goodwill was not impaired. There has been no impairment of the Olefins or Vinyls segments' goodwill since the goodwill was initially recorded. Other intangible assets with finite lives are amortized over their estimated useful lives and reviewed for impairment in accordance with the provisions of the accounting guidance. See Note 7 for more information on the Company's annual goodwill impairment tests.

Turnaround Costs

The Company accounts for turnaround costs under the deferral method. Turnarounds are the scheduled and required shutdowns of specific operating units in order to perform planned major maintenance activities. The costs related to the significant overhaul and refurbishment activities include maintenance materials, parts and direct labor costs. The costs of the turnaround are deferred when incurred at the time of the turnaround and amortized (within depreciation and amortization) on a straight-line basis until the next planned turnaround, which ranges from three to six years. Deferred turnaround costs are presented as a component of other assets, net. The cash outflows related to these costs are included in operating activities in the consolidated statement of cash flows.

Business Combinations

The Company records business combinations using the acquisition method of accounting. Under the acquisition method of accounting, identifiable assets acquired and liabilities assumed are recorded at their acquisition date fair values. The excess of the purchase price over the estimated fair value is recorded as goodwill. Changes in the estimated fair values of net assets recorded for acquisitions prior to the finalization of more detailed analysis, but not to exceed one year from the date of acquisition, will adjust the amount of the purchase price allocable to goodwill. Measurement period adjustments are reflected in the period in which they occur.

Income Taxes

The Company utilizes the liability method of accounting for deferred income taxes. Under the liability method, deferred tax assets or liabilities are recorded based upon temporary differences between the tax basis of assets and liabilities and their carrying values for financial reporting purposes. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities during the period. Valuation allowances are recorded against deferred tax assets when it is considered more likely than not that the deferred tax assets will not be realized.

On December 22, 2017, the United States ("U.S.") Tax Cuts and Jobs Act (the "Tax Act") was signed into law. The Tax Act, among other changes, reduces the U.S. corporate income tax rate from 35% to 21%, effective January 1, 2018, and also requires a one-time deemed repatriation of foreign earnings at specified rates. The Company made a provisional adjustment of $591 of income tax benefit in the 2017 consolidated financial statements for items that the Company could reasonably estimate such as revaluation of deferred tax assets and liabilities and a one-time U.S. tax on the mandatory deemed repatriation of the Company's post-1986 foreign earnings. For additional information, see Note 15.

Foreign Currency Translation

Assets and liabilities of foreign subsidiaries are translated to U.S. dollars at the exchange rate as of the end of the year. Statement of operations items are translated at the average exchange rate for the year. The resulting translation adjustment is recorded as a separate component of stockholders' equity.

Revenue Recognition

Revenue is recognized when persuasive evidence of an arrangement exists, products are delivered to the customer, the sales price is fixed or determinable and collectability is reasonably assured. For domestic contracts, title and risk of loss passes to the customer upon delivery under executed customer purchase orders or contracts. For export contracts, the title and risk of loss passes to customers at the time specified by each contract. Provisions for discounts, rebates and returns are provided for in the same period as the related sales are recorded.

Transportation and Freight

Amounts billed to customers for freight and handling costs on outbound shipments are included in net sales in the consolidated statements of operations. Transportation and freight costs incurred by the Company on outbound shipments are included in cost of sales in the consolidated statements of operations.

Price Risk Management

The accounting guidance for derivative instruments and hedging activities requires that the Company recognize all derivative instruments on the balance sheet at fair value, and changes in the derivative's fair value must be currently recognized in earnings or comprehensive income, depending on the designation of the derivative. If the derivative is designated as a fair value hedge, the changes in the fair value of the derivative and of the hedged item attributable to the hedged risk are recognized in earnings. If the derivative is designated as a cash flow hedge, the effective portion of the change in the fair value of the derivative is recorded in comprehensive income and is recognized in the statement of operations when the hedged item affects earnings. Ineffective portions of changes in the fair value of cash flow hedges are recognized in earnings currently.

Asset Retirement Obligations

The Company has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Company's manufacturing facilities.

The Company recognizes asset retirement obligations in the period in which the liability becomes probable and reasonably estimable. Recognized asset retirement obligations are initially recorded at fair value and capitalized as a component of the carrying value of the long-lived asset to which the obligation relates. The liability is accreted to its future value each period, and the capitalized cost is depreciated over the estimated useful life of the related asset. Upon settlement of the liability, a gain or loss is recorded. As of December 31, 2017, the Company had $3 and $18 of asset retirement obligations recorded as accrued liabilities and other liabilities, respectively. As of December 31, 2016, the Company had $4 and $17 of asset retirement obligations recorded as accrued liabilities and other liabilities, respectively.

The Company also has conditional asset retirement obligations that have not been recognized because the fair values of the conditional legal obligations cannot be measured due to the indeterminate settlement date of the obligations. Settlements of the unrecognized conditional asset retirement obligations are not expected to have a material adverse effects on the Company's financial condition, results of operations or cash flows in any individual reporting period.

Environmental Costs

Environmental costs relating to current operations are expensed or capitalized, as appropriate, depending on whether such costs provide future economic benefits. Remediation liabilities are recognized when the costs are considered probable and can be reasonably estimated. Measurement of liabilities is based on currently enacted laws and regulations, existing technology and undiscounted site-specific costs. Environmental liabilities in connection with properties that are sold or closed are realized upon such sale or closure, to the extent they are probable and estimable and not previously reserved. Recognition of any joint and several liabilities is based upon the Company's best estimate of its final pro rata share of the liability.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Recent Accounting Pronouncements

Revenue from Contracts with Customers (ASU No. 2014-09)

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that will supersede the existing revenue recognition guidance. The new accounting guidance creates a framework by which an entity will allocate the transaction price to separate performance obligations and recognize revenue when each performance obligation is satisfied. Under the new standard, entities will be required to use judgment and make estimates, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price, allocating the transaction price to each separate performance obligation and determining when an entity satisfies its performance obligations. The standard allows for either "full retrospective" adoption, meaning that the standard is applied to all of the periods presented with a cumulative catch-up as of the earliest period presented, or "modified retrospective" adoption, meaning the standard is applied only to the most current period presented in the financial statements with a cumulative catch-up as of the current period. In July and December 2016, the FASB issued various additional authoritative guidance for the new revenue recognition standard. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. The Company has elected the modified retrospective method of adoption.

Recognition and Measurement of Financial Assets and Financial Liabilities (ASU No. 2016-01)

In January 2016, the FASB issued an accounting standards update making certain changes principally to the current guidance for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. Among other things, the guidance (1) requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value, with changes in fair value recognized in net income; (2) provide entities with a policy election to record equity investments without readily determinable fair values at cost, less impairment, and subsequent adjustments for observable price changes (changes in the basis of these equity investments to be reported in net income); (3) requires an entity that has elected the fair value option for financial liabilities to recognize changes in fair value due to instrument-specific credit risk separately in other comprehensive income; (4) clarified current guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities; and (5) requires specific disclosure pertaining to financial assets and financial liabilities in the financial statements. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Leases (ASU No. 2016-02)

In February 2016, the FASB issued an accounting standards update on a new lease standard that will supersede the existing lease guidance. The standard requires a lessee to recognize assets and liabilities related to long-term leases that are classified as operating leases under current guidance on its balance sheet. An asset would be recognized related to the right to use the underlying asset and a liability would be recognized related to the obligation to make lease payments over the term of the lease. The standard also requires expanded disclosures related to leases. The accounting standard will be effective for reporting periods beginning after December 15, 2018. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows.

Credit Losses (ASU No. 2016-13)

In June 2016, the FASB issued an accounting standards update providing new guidance for the accounting for credit losses on loans and other financial instruments. The new guidance introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. The standard also modifies the impairment model for available-for-sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. The accounting standard will be effective for reporting periods beginning after December 15, 2019 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Cash Flows (ASU No. 2016-15)

In August 2016, the FASB issued an accounting standards update providing new guidance on the classification of certain cash receipts and payments including debt extinguishment costs, debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments, proceeds from the settlement of insurance claims and life insurance policies and distributions received from equity method investees in the statement of cash flows. This update is required to be applied using the retrospective transition method to each period presented unless it is impracticable to be applied retrospectively. In such situation, this guidance is to be applied prospectively. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Cash Flows (ASU No. 2016-18)

In November 2016, the FASB issued an accounting standards update to clarify certain existing principles in Accounting Standards Codification ("ASC") 230, Cash flows, including providing additional guidance related to transfers between cash and restricted cash and how entities present, in their statement of cash flows, the cash receipts and cash payments that directly affect the restricted cash accounts. The accounting standard will be effective for reporting periods beginning after December 15, 2017. Upon adoption, the Company will retrospectively adjust its financial statements to reflect restricted cash in the beginning and ending cash and restricted cash balances within the statements of cash flows. Transfers between cash and restricted cash will be excluded from net changes in cash and cash equivalents within the statements of cash flows.

Business Combinations (ASU No. 2017-01)

In January 2017, the FASB issued an accounting standards update to assist entities with evaluating when a set of transferred assets and activities is a business. The guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs by more closely aligning it with how outputs are described in ASC 606. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Intangibles-Goodwill and Other (ASU No. 2017-04)

In January 2017, the FASB issued an accounting standards update to simplify the subsequent measurement of goodwill. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The accounting standard will be effective for reporting periods beginning after December 15, 2019 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (ASU No. 2017-05)

In February 2017, the FASB issued an accounting standards update to clarify the scope of guidance related to other income—gains and losses from the derecognition of nonfinancial assets, and to add guidance for partial sales of nonfinancial assets. The new guidance clarifies that an in substance nonfinancial asset is an asset or group of assets for which substantially all of the fair value consists of nonfinancial assets and the group or subsidiary is not a business. The guidance also outlines that when an entity transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling interest, it will measure the retained interest at fair value resulting in full gain or loss recognition upon sale of the controlling interest. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Compensation - Retirement Benefits (ASU No. 2017-07)

In March 2017, the FASB issued an accounting standards update to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. The new guidance requires employers to disaggregate the service cost component from the other components of net periodic benefit cost and report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The amendments also allow only the service cost component to be eligible for capitalization when applicable. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Compensation - Stock Compensation (ASU No. 2017-09)

In May 2017, the FASB issued the accounting standards update to provide clarity and reduce both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in this update provide guidance about which changes to the terms or conditions of a share-based payment award require the application of modification accounting in Topic 718. Essentially, an entity will not have to account for the effects of a modification if: (1) the fair value of the modified award is the same immediately before and after the modification; (2) the vesting conditions of the modified award are the same immediately before and after the modification; and (3) the classification of the modified award as either an equity instrument or liability instrument is the same immediately before and after the modification. This update is to be applied prospectively to an award modified on or after the adoption date. Early adoption is permitted. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Derivatives and Hedging - Targeted Improvements to Accounting for Hedging Activities (ASU No. 2017-12)

In August 2017, the FASB issued an accounting standards update to improve financial reporting of hedging relationships, to better portray the economic results of an entity's risk management activities in the financial statements and to simplify application of hedge accounting guidance. The accounting standard eliminates certain hedge effectiveness measurement and reporting requirements and expands the types of permissible hedging strategies. The accounting standard will be effective for reporting periods beginning after December 15, 2018, and interim periods within those fiscal years. Early application is permitted in any interim period after issuance, to be applied retrospectively to the beginning of the fiscal year. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows.

Recently Adopted Accounting Standards

Investments-Equity Method and Joint Ventures (ASU No. 2016-07)

In March 2016, the FASB issued an accounting standards update providing new guidance for the accounting for equity method investments. The new guidance eliminates the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. In addition, the guidance requires that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. Therefore, upon qualifying for the equity method of accounting, no retroactive adjustment of the investment is required. The accounting standard is effective for reporting periods beginning after December 15, 2016. The Company adopted this accounting standard effective January 1, 2017 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Stock Compensation (ASU No. 2016-09)

In March 2016, the FASB issued an accounting standards update to simplify several aspects of the accounting for share-based payment transactions, including income tax consequences, classifications of awards as either equity or liabilities and certain related classifications on the statement of cash flows. In addition, the new guidance permits entities to make an accounting policy election for the impact of forfeitures on the recognition of expense for share-based payment awards. Forfeitures can be estimated, as required today, or recognized when they occur. The accounting standard is effective for reporting periods beginning after December 15, 2016. The Company adopted this accounting standard effective January 1, 2017 and elected to continue estimating forfeitures as required prior to adoption of the accounting standards update. The adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Amendments to the Consolidation Analysis (ASU No. 2016-17)

In October 2016, the FASB issued an accounting standards update making certain changes to the current consolidation guidance. The amendments affect reporting entities that are required to evaluate whether they should consolidate a variable interest entity in certain situations involving entities under common control. Specifically, the amendments change the evaluation of whether a reporting entity is the primary beneficiary of a variable interest entity by changing how a reporting entity that is a single decision maker of a variable interest entity treats indirect interests in the entity held through related parties that are under common control with the reporting entity. The amendments will be effective for annual periods beginning after December 15, 2016. The Company adopted this accounting standard, applied prospectively, effective January 1, 2017, and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Acquisitions

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Acquisitions

Axiall Corporation

On August 31, 2016, the Company completed its acquisition of, and acquired all the remaining equity interest in, Axiall, a Delaware corporation. Prior to the acquisition, the Company held 3.1 million shares in Axiall. Pursuant to the terms of the Merger Agreement, dated as of June 10, 2016, by and among Westlake, Axiall and the Merger Sub, the Company acquired all of the remaining issued and outstanding shares of common stock of Axiall for $33.00 per share in cash. Pursuant to the Merger Agreement, Merger Sub was merged with and into Axiall, and Axiall survived the Merger as a wholly-owned subsidiary of the Company. The combined company is the third-largest global chlor-alkali producer and the third-largest global PVC producer. The Company's management believes that this strategic acquisition will enhance its strategy of integration and will further strengthen its role in the North American markets.

Axiall produces a highly integrated chain of chlor-alkali and derivative products, including chlorine, caustic soda, vinyl chloride monomer ("VCM"), PVC resin, PVC compounds and chlorinated derivative products. Axiall also manufactures and sells building products, including siding, trim, mouldings, pipe and pipe fittings.

Total consideration transferred for the Merger was $2,540. The Merger was accounted for under the acquisition method of accounting. The assets acquired and liabilities assumed and the results of operations of the acquired business are included in the Company's Vinyls segment.

For the year ended December 31, 2016, the Company recognized $104 of transaction and integration-related costs. This included acquisition-related costs of $49 for advisory, consulting and professional fees and other expenses during the year ended December 31, 2016. Transaction and integration-related costs also included $55 during the year ended December 31, 2016 related to the settlement of Axiall share-based awards, retention agreement costs and severance benefits provided to former Axiall employees in connection with the Merger.

The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition. The allocation of the consideration transferred is based on management's estimates, judgments and assumptions. When determining the fair values of assets acquired, liabilities assumed and noncontrolling interests of the acquiree, management made significant estimates, judgments and assumptions. Management estimated that consideration paid exceeded the fair value of the net assets acquired. Therefore, goodwill of $942 was recorded. The goodwill recognized is primarily attributable to synergies related to the Company's vinyls integration strategy that are expected to arise from the Merger. All of the goodwill is assigned to the Company's Vinyls segment. As a portion of the goodwill arising from the Merger is attributable to foreign operations, there will be a continuing foreign currency impact to goodwill in the consolidated financial statements.



	Final Purchase Consideration as of August 31, 2016
Closing stock purchase:
Offer per share	$	33.00
Multiplied by number of shares outstanding at acquisition (in thousands of shares)	67,277
Fair value of Axiall shares outstanding purchased by the Company	2,220
Plus:
Axiall debt repaid at acquisition	247
Seller's transaction costs paid by the Company ⁽¹⁾	48
Total fair value of consideration transferred	2,515

Fair value of Axiall share-based awards attributed to pre-combination service ⁽²⁾	12
Additional settlement value of shares acquired	13
Purchase consideration	2,540

Fair value of previously held equity interest in Axiall ⁽³⁾	102
Total fair value allocated to net assets acquired	$	2,642

______________________________


(1)	Transactions costs incurred by the seller included legal and advisory costs incurred for the benefit of Axiall's former shareholders and board of directors to evaluate the Company's initial Merger proposals, explore strategic alternatives and negotiate the purchase price.


(2)	The fair value of share-based awards attributable to pre-combination service includes the ratio of the pre-combination service performed to the original service period of the Axiall restricted share units and options, including related dividend equivalent rights.


(3)	Prior to the Merger, the Company owned 3.1 million shares in Axiall. The investment in Axiall was carried at estimated fair value with unrealized gains recorded as a component of accumulated other comprehensive loss in the consolidated balance sheet. The Company recognized a $49 gain for the investment in other income, net in the consolidated statements of operations upon gaining control.

The following table summarizes the purchase price allocation:



	Net Assets Acquired as of August 31, 2016
Cash	$	88
Accounts receivable ⁽¹⁾	422
Income tax receivable	51
Inventories ⁽²⁾	349
Prepaid expenses and other current assets	56
Property, plant and equipment ⁽²⁾	2,942
Customer relationships (weighted average lives of 9.8 years) ⁽³⁾	670
Other intangible assets:
Trade name (weighted average lives of 6.8 years)	50
Technology (weighted average lives of 5.4 years)	42
Supply contracts and leases (weighted average lives of 6.3 years)	27
Other assets	94
Total assets acquired	$	4,791
Accounts and notes payable	254
Interest payable	8
Income tax payable	2
Accrued compensation	44
Accrued liabilities	154
Deferred income taxes ⁽⁴⁾	958
Tax reserve non-current	3
Pension and other post-retirement obligations	311
Other liabilities	102
Long-term debt	1,187
Total liabilities assumed	$	3,023
Total identifiable net assets acquired	$	1,768
Noncontrolling interest	(68		)
Goodwill	942
Total fair value allocated to net assets acquired	$	2,642

______________________________


(1)	The fair value of accounts receivable acquired was $422, with the gross contractual amount being $435. The Company expects $13 to be uncollectible.


(2)	The Company obtained additional information related to its inventories and property, plant and equipment, which led to an increase in inventories of $43, a decrease in property plant and equipment of $193 and a corresponding increase in goodwill of $150 compared to the estimated fair values included in the 2016 Form 10-K.


(3)	The Company obtained additional information related to its customer relationship balances which led to an increase in customer relationships of $80 and a corresponding decrease in goodwill compared to the estimated fair values included in the 2016 Form 10-K.


(4)	Decreases in the estimated fair values of identified assets acquired led to a decrease in deferred income taxes of $27 compared to the estimated fair values included in the 2016 Form 10-K.

The acquired business contributed net sales and net loss of $976 and $96, respectively, to the Company for the period from August 31, 2016 to December 31, 2016. The net loss for the period from August 31, 2016 to December 31, 2016 included integration-related costs and the negative impact of selling higher cost Axiall inventory recorded at fair value. The following unaudited consolidated pro forma information presents consolidated pro forma information as if the Merger had occurred on January 1, 2015:



	Pro Forma
	Year Ended December 31,
	2016		2015
Net sales	$	7,081	$	7,793

Net income ⁽¹⁾	$	397	$	663
Net income (loss) attributable to noncontrolling interest	23		(2		)
Net income attributable to Westlake Chemical Corporation ⁽¹⁾	$	374	$	665
Earnings per common share attributable to Westlake Chemical Corporation:
Basic	$	2.88	$	5.02
Diluted	$	2.86	$	5.00

______________________________

(1)

The 2016 pro forma net income amounts include Axiall's historical charges recorded during the eight-month period prior to the closing of the Merger for (1) divestitures; (2) restructuring; and (3) legal and settlement claims, net, of $27, $23 and $23, respectively. These amounts have not been eliminated for pro forma results because they do not relate to nonrecurring transaction-specific costs related to the Merger.

The pro forma amounts above have been calculated after applying the Company's accounting policies and adjusting the Axiall results to reflect (1) the increase to depreciation and amortization that would have been charged assuming the fair value adjustments to property, plant and equipment and intangible assets had been applied from January 1, 2015; (2) the elimination of net sales and cost of sales between the Company and Axiall; (3) additional pension service costs; (4) amortization of debt premium and accretion of asset retirement obligations and environmental liabilities as part of the Company's adjustments to fair value; (5) incremental interest expense that would have been incurred assuming the financing arrangements entered into by the Company and the repayment of a portion of Axiall's outstanding debt had occurred on January 1, 2015; (6) the elimination of transaction-related costs; (7) the elimination of Axiall's goodwill impairment charges during 2015; and (8) an adjustment to tax-effect the aforementioned pro forma adjustments using an estimated aggregate statutory income tax rate of the jurisdictions to which the above adjustments relate. The pro forma amounts do not include any potential synergies, cost savings or other expected benefits of the Merger, are presented for illustrative purposes only and are not necessarily indicative of results that would have been achieved if the Merger had occurred as of January 1, 2015 or of future operating performance.

Suzhou Huasu Plastics Co., Ltd.

On June 1, 2015, the Company acquired an additional 35.7% equity interest in Suzhou Huasu Plastics Co., Ltd. ("Huasu") from INEOS Chlor Vinyls Holdings B.V., increasing its interest in Huasu to 95%. Huasu is a PVC joint venture based near Shanghai, in the People's Republic of China and has a combined annual capacity of approximately 300 million pounds of PVC resin and 145 million pounds of PVC film and sheet.

Prior to the acquisition of this 35.7% interest, the Company owned a 59.3% interest in Huasu. The Company accounted for the investment using the equity method of accounting because Huasu did not meet the definition of a variable interest entity and because contractual arrangements giving certain substantive participatory rights to minority shareholders prevented the Company from exercising a controlling financial interest over Huasu. As a result of the Company obtaining control over Huasu, the Company's 59.3% interest was remeasured to fair value, resulting in a loss of $2, which is included in other income, net in the consolidated statement of operations for the year ended December 31, 2015.

The closing date purchase price of $6 was paid with available cash on hand. The acquisition was accounted for under the acquisition method of accounting. The transaction resulted in a bargain purchase acquisition-date gain of $23 and is recognized in other income, net in the consolidated statement of operations for the year ended December 31, 2015. The Company believes there are several factors that contributed to this transaction resulting in a bargain purchase acquisition-date gain, including the slowdown in the growth of, and current weakness in, the Chinese economy. The assets acquired and liabilities assumed and the results of operations of this acquired business are included in the Vinyls segment.

Financial Instruments

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Financial Instruments

Cash Equivalents

The Company had $644 and $0 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at December 31, 2017 and 2016, respectively. The Company's investments in held-to-maturity securities were held at amortized cost, which approximates fair value.

Restricted Cash and Cash Equivalents

The Company had restricted cash and cash equivalents of $23 at December 31, 2017, which was primarily related to balances that are restricted for payment of distributions to certain of the Company's current and former employees. The Company had restricted cash and cash equivalents of $186 at December 31, 2016, which was primarily related to the balances deposited with and held as security by the lender under the Company's prior term loan facility and for distributions to certain of the Company's current and former employees. The current portion of restricted cash and cash equivalents was $1 and $161 at December 31, 2017 and 2016, respectively. The non-current portion of restricted cash and cash equivalents was $22 and $25 at December 31, 2017 and 2016, respectively, and is reflected under other assets, net in the consolidated balance sheets.

Available-for-Sale Marketable Securities

The Company had no available-for-sale securities at December 31, 2017 and 2016. The proceeds from sales and maturities of available-for-sale securities included in the consolidated statements of cash flows and the gross realized gains included in the consolidated statements of operations are reflected in the table below. No gross realized losses were realized during these periods. The cost of securities sold was determined using the specific identification method.



	Year Ended December 31,
	2017		2016		2015
Proceeds from sales and maturities of securities	$	—	$	663	$	49
Gross realized gains	—		54		4

Accounts Receivable

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Accounts Receivable

Accounts receivable consist of the following at December 31:



	2017			2016
Trade customers	$	974		$	820
Affiliates	9			8
Allowance for doubtful accounts	(22		)	(18		)
	961			810
Federal and state taxes	7			90
Other	33			39
Accounts receivable, net	$	1,001		$	939

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventories

12 Months Ended

Dec. 31, 2017

Inventory, Net [Abstract]

Inventories

Inventories consist of the following at December 31:



	2017		2016
Finished products	$	549	$	501
Feedstock, additives and chemicals	221		217
Materials and supplies	130		83
Inventories	$	900	$	801

Property, Plant And Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment, Net [Abstract]

Property, Plant And Equipment

Property, Plant and Equipment

Property, plant and equipment consist of the following at December 31:



	2017			2016
Land	$	198		$	194
Buildings and improvements	495			465
Plant and equipment	7,281			6,914
Other	388			377
	8,362			7,950
Less: Accumulated depreciation	(2,338		)	(1,919		)
	6,024			6,031
Construction in progress	388			389
Property, plant and equipment, net	$	6,412		$	6,420

Depreciation expense on property, plant and equipment of $449, $305 and $209 is included in cost of sales in the consolidated statements of operations for the years ended December 31, 2017, 2016 and 2015, respectively.

Goodwill, Intangibles and Other Assets

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill, Intangibles and Other Assets

Other Assets

Goodwill

The gross carrying amounts of goodwill for the years ended December 31, 2017 and 2016 are as follows:



	Olefins Segment		Vinyls Segment			Total
Balance at December 31, 2015	$	30	$	32		$	62
Goodwill acquired during the year	—		888			888
Effects of changes in foreign exchange rates	—		(3		)	(3		)
Balance at December 31, 2016	30		917			947
Measurement period adjustment	—		55			55
Effects of changes in foreign exchange rates	—		10			10
Balance at December 31, 2017	$	30	$	982		$	1,012

Olefins Segment Goodwill

The fair value of the Olefins segment, the reporting unit assessed during October 2017, was calculated using both a discounted cash flow methodology and a market value methodology.

The discounted cash flow projections were based on a nine-year forecast, from 2018 to 2026, to reflect the cyclicality of the Company's Olefins business. The forecast was based on prices and spreads projected by IHS Markit ("IHS"), a chemical industry organization offering market and business advisory services for the chemical market, historical results and estimates by management, including its strategic and operational plans. Other significant assumptions used in the discounted cash flow projection included sales volumes based on production capacities. The future cash flows were discounted to present value using a discount rate of 8%. The significant assumptions used in determining the fair values of the reporting units using the market value methodology included the determination of appropriate market comparables and the estimated multiples of EBITDA a willing buyer was likely to pay.

Vinyls Segment Goodwill

Due to the Merger, the Company reorganized the reporting units of the Vinyls segment during 2017. Goodwill was reassigned based on a relative fair value approach. The fair values of the North America, Europe, Taiwan and China reporting units assessed during the April 2017 impairment test were calculated using both a discounted cash flow methodology and a market value methodology.

The discounted cash flow projections were based on a nine-year forecast, from 2018 to 2026 to reflect the cyclicality of the housing and construction markets as the Company's Vinyls businesses are significantly influenced by those markets. The forecast was based on prices and spreads projected by IHS, historical results and estimates by management, including its strategic and operational plans. Other significant assumptions used in the discounted cash flow projection included sales volumes based on production capacities. The future cash flows were discounted to present value using a discount rate ranging from 9% to 12%. The significant assumptions used in determining the fair values of the reporting units using the market value methodology include the determination of appropriate market comparables and the estimated multiples of EBITDA a willing buyer is likely to pay.

Intangible Assets

Intangible assets consisted of the following at December 31:



	2017							2016							Weighted Average Life
	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net		Weighted Average Life
Customer relationships	$	754	$	(138	)	$	616	$	662	$	(51	)	$	611	10
Other intangible assets:
Licenses and intellectual property	124		(55		)	69		121		(44		)	77		13
Trademarks	93		(17		)	76		88		(7		)	81		13
Other	31		(15		)	16		31		(13		)	18		12
Total other intangible assets	$	248	$	(87	)	$	161	$	240	$	(64	)	$	176

Scheduled amortization of intangible assets for the next five years is as follows: $107, $106, $105, $103 and $81 in 2018, 2019, 2020, 2021 and 2022, respectively.

Other Assets, net

Other assets, net include net turnaround costs, cost-method investments, equity-method investments, restricted cash and deferred charges.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Term Loan	12 Months Ended
Term Loan	Dec. 31, 2017
Debt Disclosure [Abstract]
Term Loan	Term Loan On August 10, 2016, an indirect subsidiary of the Company, Westlake International Holdings II C.V., a limited partnership organized under the laws of the Netherlands (the "CV Borrower"), entered into a credit agreement with Bank of America, N.A., as agent and lender, providing the CV Borrower with a $150 term loan facility. The term loan facility had a scheduled maturity date of March 31, 2017. The term loan was fully repaid in January 2017. The loans thereunder bore interest at a floating interest rate equal to LIBOR plus 2% per annum, payable in arrears on the last day of each three-month period following the date of funding and at maturity.

Long-Term Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Long-Term Debt

Long-term debt consisted of the following at December 31:



	December 31, 2017							December 31, 2016
	Principal Amount		Unamortized Premium, Discount and Debt Issuance Costs			Net Long-Term Debt		Principal Amount		Unamortized Premium, Discount and Debt Issuance Costs			Net Long-Term Debt
Revolving credit facility	$	—	$	—		$	—	$	325	$	—		$	325
4.625% senior notes due 2021 (the "4.625% Westlake 2021 Senior Notes")	625		20			645		625		27			652
4.625% senior notes due 2021 (the "4.625% Subsidiary 2021 Senior Notes")	63		2			65		63		3			66
3.60% senior notes due 2022 (the "3.60% 2022 Senior Notes")	250		(1		)	249		250		(2		)	248
4.875% senior notes due 2023 (the "4.875% Westlake 2023 Senior Notes")	434		11			445		434		13			447
4.875% senior notes due 2023 (the "4.875% Subsidiary 2023 Senior Notes")	16		—			16		16		1			17
3.60% senior notes due 2026 (the "3.60% 2026 Senior Notes")	750		(10		)	740		750		(11		)	739
Loan related to tax-exempt waste disposal revenue bonds due 2027	11		—			11		11		—			11
6 ½% senior notes due 2029 (the "6 ½% 2029 GO Zone Senior Notes")	100		(1		)	99		100		(1		)	99
6 ¾% senior notes due 2032 (the "6 ¾% 2032 GO Zone Senior Notes")	—		—			—		250		(2		)	248
6 ½% senior notes due 2035 (the "6 ½% 2035 GO Zone Senior Notes")	89		(1		)	88		89		(1		)	88
6 ½% senior notes due 2035 (the "6 ½% 2035 IKE Zone Senior Notes")	65		—			65		65		—			65
5.0% senior notes due 2046 (the "5.0% 2046 Senior Notes")	700		(25		)	675		700		(26		)	674
4.375% senior notes due 2047 (the "4.375% 2047 Senior Notes")	500		(9		)	491		—		—			—
3.50% senior notes due 2032 (the "3.50% 2032 Go Zone Refunding Senior Notes")	250		(2		)	248		—		—			—
Total long-term debt	3,853		(16		)	3,837		3,678		1			3,679
Less: Current portion - 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes	688		22			710		—		—			—
Long-Term Debt, net of current portion	$	3,165	$	(38	)	$	3,127	$	3,678	$	1		$	3,679

Credit Agreement

The Company has a $1,000 revolving credit facility that matures on August 23, 2021. The Credit Agreement bears interest at either (a) LIBOR plus a spread ranging from 1.00% to 1.75% or (b) Alternate Base Rate plus a spread ranging from 0.00% to 0.75%, in each case depending on the credit rating of the Company. As of December 31, 2017, the Company had no borrowings outstanding under the Credit Agreement. As of December 31, 2017, the Company had outstanding letters of credit totaling $6 and borrowing availability of $994 under the Credit Agreement. The obligations of the Company under the Credit Agreement are guaranteed by current and future material domestic subsidiaries of the Company, subject to certain exceptions. The Credit Agreement contains certain affirmative and negative covenants, including a quarterly total leverage ratio financial maintenance covenant. The Credit Agreement also contains certain events of default and if and for so long as an event of default has occurred and is continuing, any amounts outstanding under the Credit Agreement will accrue interest at an increased rate, the Lenders can terminate their commitments thereunder and payments of any outstanding amounts could be accelerated by the Lenders. As of December 31, 2017, the Company is in compliance with the total leverage ratio financial maintenance covenant.

3.60% Senior Notes due 2026 and 5.0% Senior Notes due 2046

In August 2016, the Company issued $750 aggregate principal amount of the 3.60% 2026 Senior Notes and $700 aggregate principal amount of the 5.0% 2046 Senior Notes. In March 2017 the Company commenced registered exchange offers to exchange the 3.60% 2026 Senior Notes and the 5.0% 2046 Senior Notes for new notes that are identical in all material respects to the 3.60% 2026 Senior Notes and the 5.0% 2046 Senior Notes, except that the offer and issuance of the new Securities and Exchange Commission ("SEC")-registered notes have been registered under the Securities Act of 1933, as amended (the "Securities Act"). The exchange offers expired on April 24, 2017, and approximately 99.97% of the 3.60% 2026 Senior Notes and 100% of the 5.0% 2046 Senior Notes were exchanged. The 3.60% 2026 Senior Notes that were not exchanged in the 3.60% 2026 Senior Notes exchange offer have not been registered under the Securities Act or any state securities laws and may not be offered or sold in the U.S. absent registration or an applicable exemption from registration requirements or a transaction not subject to the registration requirements of the Securities Act or any state securities law.

4.625% Senior Notes due 2021 and 4.875% Senior Notes due 2023

In September 2016, the Company issued $625 aggregate principal amount of the 4.625% Westlake 2021 Senior Notes and $434 aggregate principal amount of the 4.875% Westlake 2023 Senior Notes upon the closing of the Company's offers to exchange any and all of the $688 aggregate principal amount of the outstanding 4.625% senior notes due 2021 issued by Eagle Spinco Inc., a wholly-owned subsidiary of Axiall ("Eagle Spinco"), and the $450 aggregate principal amount of the outstanding 4.875% senior notes due 2023 issued by Axiall. In the exchange offers, $625 aggregate principal amount of the 4.625% Westlake 2021 Senior Notes and $434 aggregate principal amount of the 4.875% Westlake 2023 Senior Notes were issued by the Company, leaving outstanding $63 aggregate principal amount of the 4.625% Subsidiary 2021 Senior Notes and $16 aggregate principal amount of the 4.875% Subsidiary 2023 Senior Notes. In March 2017, the Company commenced registered exchange offers to exchange the 4.625% Westlake 2021 Senior Notes and the 4.875% Westlake 2023 Senior Notes for new SEC-registered notes that are identical in all material respects to the 4.625% Westlake 2021 Senior Notes and the 4.875% Westlake 2023 Senior Notes, except that the offer and issuance of the new notes have been registered under the Securities Act. The exchange offers expired on April 24, 2017, and 100% of both the 4.625% Westlake 2021 Senior Notes and the 4.875% Westlake 2023 Senior Notes were exchanged.

In December 2017, the Company delivered irrevocable notices for the optional redemption of all of the outstanding 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes (collectively, the "2021 Notes"). The 2021 Notes were redeemed on February 15, 2018 at a redemption price equal to 102.313% of the principal amount of the 2021 Notes plus accrued and unpaid interest on the 2021 Notes to the redemption date. The 2021 Notes were classified as a component of current liabilities in the consolidated balance sheet at December 31, 2017, based on the terms of the redemption.

3.60% Senior Notes due 2022

In July 2012, the Company issued $250 aggregate principal amount of the 3.60% 2022 Senior Notes. The 3.60% 2022 Senior Notes are unsecured and were issued with an original issue discount of $1. There is no sinking fund and no scheduled amortization of the 3.60% 2022 Senior Notes prior to maturity. The Company may optionally redeem the 3.60% 2022 Senior Notes in accordance with the terms of the 3.60% 2022 Senior Notes. All of the Company's domestic subsidiaries that guarantee other indebtedness of the Company or of another guarantor of the 3.60% 2022 Senior Notes in excess of $5 are guarantors of the 3.60% 2022 Senior Notes.

4.375% Senior Notes due 2047

In November 2017, the Company completed the registered public offering of $500 aggregate principal amount of the 4.375% 2047 Senior Notes. The 4.375% 2047 Senior Notes are unsecured and mature on November 15, 2047. There is no sinking fund and no scheduled amortization of the 4.375% 2047 Senior Notes prior to maturity. The Company may optionally redeem the 4.375% 2047 Senior Notes in accordance with the terms of the 4.375% 2047 Senior Notes. All of the Company's domestic subsidiaries that guarantee other indebtedness of the Company or another guarantor or the 4.375% 2047 Senior Notes in excess of $40 are guarantors of the 4.375% 2047 Senior Notes.

The indenture governing the 3.60% 2026 Senior Notes, the 5.0% 2046 Senior Notes, the 4.625% Westlake 2021 Senior Notes, the 4.875% Westlake 2023 Senior Notes, 3.60% 2022 Senior Notes and 4.375% 2047 Senior Notes contains customary events of default and covenants that will restrict the Company and certain of the Company's subsidiaries' ability to (1) incur certain secured indebtedness, (2) engage in certain sale-leaseback transactions and (3) consolidate, merge or transfer all or substantially all of its assets.

IKE Zone Bonds

In December 2010, the Louisiana Local Government Authority Environmental Facilities and Community Development Authority (the "Authority"), a political subdivision of the State of Louisiana, completed the offering of $65 of 6 ½% tax-exempt revenue bonds due November 1, 2035 (the "6 ½% 2035 IKE Zone Senior Notes") under Section 704 of the Emergency Economic Stabilization Act of 2008 (the "IKE Zone Act").

GO Zone Bonds

In December 2010, the Authority issued $89 of 6 ½% tax-exempt revenue bonds due November 1, 2035 under the Gulf Opportunity Zone Act of 2005 (the "GO Zone Act") (the "6 ½% 2035 GO Zone Bonds"). In connection with the issuance of the 6 ½% 2035 GO Zone Bonds, the Company issued $89 of the 6 ½% 2035 GO Zone Senior Notes. In July 2010, the Authority completed the reoffering of $100 of 6 ½% tax-exempt revenue bonds due August 1, 2029 under the GO Zone Act (the "6 ½% 2029 GO Zone Bonds"). In connection with the reoffering of the 6 ½% 2029 GO Zone Bonds, the Company issued $100 of the 6 ½% 2029 GO Zone Senior Notes. In December 2007, the Authority issued $250 of 6 ¾% tax-exempt revenue bonds due November 1, 2032 under the GO Zone Act (the "6 ¾% 2032 GO Zone Bonds"). In connection with the issuance of the 6 ¾% 2032 GO Zone Bonds, the Company issued $250 of the 6 ¾% 2032 GO Zone Senior Notes.

Each series of the tax-exempt bonds is subject to redemption and the holders may require the bonds to be repurchased upon a change of control or a change in or loss of the current tax status of the bonds. In addition, the bonds are subject to optional redemption by the Authority upon the direction of the Company if certain events have occurred in connection with the operation of the projects for which the bond proceeds may be used, including if the Company has determined that the continued operation of any material portion of the projects would be impracticable, uneconomical or undesirable for any reason.

In September 2017, the Company directed the Authority to optionally redeem in full the $250 aggregate principal amount of the 6 ¾% 2032 GO Zone Bonds on November 1, 2017. In connection with the redemption of the 6 ¾% 2032 GO Zone Bonds, the Authority was required to cause the GO Zone Bonds trustee to surrender the 6 ¾% 2032 GO Zone Senior Notes to the Senior Notes trustee for cancellation. The 6 ¾% 2032 GO Zone Bonds were redeemed and the 6 ¾% 2032 GO Zone Senior Notes were cancelled on November 1, 2017.

In November 2017, the Authority completed the remarketing of $250 aggregate principal amount of 3.50% tax-exempt revenue refunding bonds due November 1, 2032 (the "3.50% 2032 GO Zone Bonds"). In connection with the remarketing of the 3.50% 2032 GO Zone Bonds, the Company issued $250 of the 3.50% 2032 Senior Notes. The 3.50% 2032 GO Zone Bonds are subject to optional redemption by the Authority upon the direction of the Company at any time on or after November 1, 2027, for 100% of the principal amount plus accrued interest. The indenture governing the 3.50% 2032 Senior Notes contains customary events of default and covenants that will restrict the Company and certain of the Company's subsidiaries' ability to (1) incur certain secured indebtedness, (2) engage in certain sale-leaseback transactions and (3) consolidate, merge or transfer all of substantially all of its assets.

In connection with each offering of the tax-exempt bonds, the Company entered into a loan agreement with the Authority pursuant to which the Company agreed to pay all of the principal, premium, if any, and interest on the bonds and certain other amounts to the Authority. The net proceeds from the offerings were loaned by the Authority to the Company. The Company used the proceeds to expand, refurbish and maintain certain of its facilities in the Louisiana Parishes of Calcasieu and Ascension. The bonds are unsecured and rank equally in right of payment with other existing and future unsecured senior indebtedness. All domestic restricted subsidiaries that guarantee other debt of the Company or of another guarantor of the 6 ½% 2029 GO Zone Senior Notes, the 3.50% 2032 Senior Notes and the 6 ½% 2035 GO Zone Senior Notes (collectively, the "GO Zone Senior Notes") and the 6 ½% 2035 IKE Zone Senior Notes (together with the Go Zone Senior Notes, the "Tax-Exempt Bond Related Senior Notes") in excess of $5 ($40 in the case of the 3.50% 2032 Senior Notes) are guarantors of the Tax-Exempt Bond Related Senior Notes. As of December 31, 2017, the Company had drawn all proceeds from the tax-exempt bonds.

The indentures governing the Tax-Exempt Bond Related Senior Notes, excluding the 3.50% 2032 Senior Notes, contain customary covenants and events of default. Accordingly, these agreements generally impose significant operating and financial restrictions on the Company. These restrictions, among other things, provide limitations on incurrence of additional indebtedness, the payment of dividends, certain investments and acquisitions and sales of assets. However, the effectiveness of certain of these restrictions is currently suspended because the Tax-Exempt Bond Related Senior Notes are currently rated investment grade by at least two nationally recognized credit rating agencies. The most significant of these provisions, if it were currently effective, would restrict the Company from incurring additional debt, except specified permitted debt (including borrowings under its credit facility), when the Company's fixed charge coverage ratio is below 2.0:1. These limitations are subject to a number of important qualifications and exceptions, including, without limitation, an exception for the payment of the Company's regular quarterly dividend of up to $0.10 per share. If the restrictions were currently effective, distributions in excess of $100 would not be allowed unless, after giving pro forma effect to the distribution, the Company's fixed charge coverage ratio is at least 2.0:1 and such payment, together with the aggregate amount of all other distributions after January 13, 2006, is less than the sum of 50% of the Company's consolidated net income for the period from October 1, 2003 to the end of the most recent quarter for which financial statements have been filed, plus 100% of net cash proceeds received after October 1, 2003 as a contribution to the Company's common equity capital or from the issuance or sale of certain securities, plus several other adjustments.

Revenue Bonds

In December 1997, the Company entered into a loan agreement with a public trust established for public purposes for the benefit of the Parish of Calcasieu, Louisiana. The public trust issued $11 principal amount of tax-exempt waste disposal revenue bonds in order to finance the Company's construction of waste disposal facilities for an ethylene plant. The waste disposal revenue bonds expire in December 2027 and are subject to redemption and mandatory tender for purchase prior to maturity under certain conditions. The interest rate on the waste disposal revenue bonds at December 31, 2017 and 2016 was 1.73% and 0.79%, respectively.

As of December 31, 2017, the Company was in compliance with all of the covenants with respect to the Tax-Exempt Bond Related Senior Notes, 4.625% Westlake 2021 Senior Notes, 4.625% Subsidiary 2021 Senior Notes, 3.60% 2022 Senior Notes, 4.875% Westlake 2023 Senior Notes, 4.875% Subsidiary 2023 Senior Notes, 3.60% 2026 Senior Notes, 5.0% 2046 Senior Notes, 4.375% 2047 Senior Notes, Credit Agreement and the waste disposal revenue bonds.

The weighted average interest rate on all long-term debt was 4.5% and 4.4% at December 31, 2017 and 2016, respectively. Unamortized debt issuance costs on long-term debt were $26 and $24 at December 31, 2017 and 2016, respectively.

Aggregate scheduled maturities of long-term debt during the next five years consist of $250 in 2022. There are no scheduled maturities of debt in 2019 through 2021. The Westlake 4.625% Senior Notes due 2021 and the Eagle Spinco Inc. 4.625% Senior Notes due 2021 were optionally redeemed on February 15, 2018.

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity The Company's Board of Directors has declared regular quarterly dividends to holders of its common stock aggregating $103, $97 and $92 for the years ended December 31, 2017, 2016 and 2015, respectively. Common Stock Each share of common stock entitles the holder to one vote on all matters on which holders are permitted to vote, including the election of directors. There are no cumulative voting rights. Accordingly, holders of a majority of the total votes entitled to vote in an election of directors will be able to elect all of the directors standing for election. Subject to preferences that may be applicable to any outstanding preferred stock, the holders of the common stock will share equally on a per share basis any dividends when, as and if declared by the Board of Directors out of funds legally available for that purpose. If the Company is liquidated, dissolved or wound up, the holders of the Company's common stock will be entitled to a ratable share of any distribution to stockholders, after satisfaction of all the Company's liabilities and of the prior rights of any outstanding class of the Company's preferred stock. The Company's common stock has no preemptive or conversion rights or other subscription rights. There are no redemption or sinking fund provisions applicable to the Company's common stock. Preferred Stock The Company's charter authorizes the issuance of shares of preferred stock. The Company's Board of Directors has the authority, without shareholder approval, to issue preferred shares from time to time in one or more series, and to fix the number of shares and terms of each such series. The Board may determine the designations and other terms of each series including dividend rates, whether dividends will be cumulative or non-cumulative, redemption rights, liquidation rights, sinking fund provisions, conversion or exchange rights and voting rights. Stock Repurchase Program In August 2011, the Company's Board of Directors authorized a stock repurchase program of the Company's common stock totaling $100 (the "2011 Program"). As of March 31, 2015, the Company had repurchased 1,944,161 shares of its common stock for an aggregate purchase price of approximately $100 under the 2011 Program, the full amount of the 2011 Program. In November 2014, the Company's Board of Directors approved a new $250 share repurchase program (the "2014 Program"). On November 20, 2015, the Company's Board of Directors approved the expansion of the 2014 Program by an additional $150. The total number of shares repurchased by the Company under the 2014 Program was none and 1,511,109 for the years ended December 31, 2017 and 2016, respectively. Any shares repurchased under the 2011 and 2014 Programs are held by the Company as treasury stock and may be used for general corporate purposes, including for the 2013 Omnibus Incentive Plan. Beginning in 2014, the Company began delivering treasury shares to employees and non-employee directors for options exercised and for the settlement of restricted stock units. The cost of treasury shares delivered was determined using the specific identification method.

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Accumulated Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive income (loss) by component were as follows:



	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2015	$	(8	)	$	(116	)	$	(5	)	$	(129	)
Other comprehensive income (loss) before reclassifications	36			(34		)	57			59
Amounts reclassified from accumulated other comprehensive income (loss)	1			—			(52		)	(51		)
Net other comprehensive income (loss) attributable to Westlake Chemical Corporation	37			(34		)	5			8
Balances at December 31, 2016	29			(150		)	—			(121		)
Other comprehensive income before reclassifications	12			114			—			126
Amounts reclassified from accumulated other comprehensive income (loss)	2			—			—			2
Net other comprehensive income attributable to Westlake Chemical Corporation	14			114			—			128
Balances at December 31, 2017	$	43		$	(36	)	$	—		$	7

The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations:



Details about Accumulated Other Comprehensive Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Year Ended December 31,
		2017			2016			2015
Amortization of pension and other post-retirement items
Net loss	(1)	$	(2	)	$	(2	)	$	(3	)
		(2		)	(2		)	(3		)
	Benefit from income taxes	—			1			1
		(2		)	(1		)	(2		)
Net unrealized gains on available-for- sale investments
Realized gain on available- for-sale investments	Other income, net	—			54			4
	Provision for income taxes	—			(2		)	(1		)
		—			52			3
Total reclassifications for the period		$	(2	)	$	51		$	1

______________________________


(1)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, see Note 12.

Employee Benefits

12 Months Ended

Dec. 31, 2017

Defined Benefit Plan [Abstract]

Employee Benefits

Defined Contribution Plans

U.S. Plans

The Company has defined contribution savings plans covering the eligible U.S. regular full-time and part-time employees, whereby eligible employees may elect to contribute up to 100% of their annual eligible compensation, subject to an annual plan limit in line with the annual elective contribution limit as determined by the Internal Revenue Service. The Company matches its employee's contribution up to a certain percentage of such employee's compensation, per the terms of the respective plans. The Company may, at its discretion and per the terms of the respective plans, make an additional non-matching contribution in an amount as the Board of Directors may determine. For the years ended December 31, 2017, 2016 and 2015, the Company recorded approximately $23, $11 and $8, respectively, to expense for these contributions.

Further, within a defined contribution savings plan, the Company also makes an annual retirement contribution to substantially all employees of one subsidiary who have completed one year of service. The Company's contributions to the plan are determined as a percentage of employees' base and overtime pay. For the years ended December 31, 2017, 2016 and 2015, the Company charged approximately $29, $17 and $12, respectively, to expense for these contributions.

Non-U.S. Plans

The Company has various defined contribution plans in Germany, United Kingdom, Italy and Belgium covering eligible employees of the Company's European operations. The Company's contributions to the plans are based on applicable laws in each country. Contributions to the Company's non-U.S. defined contribution plans are made by both the employee and the Company. For the years ended December 31, 2017, 2016 and 2015, the Company charged approximately $5, $2 and $2, respectively, to expense for its contributions to these plans.

Defined Benefit Plans

U.S. Plans

The Company has noncontributory defined benefit pension plans that cover certain eligible salaried and wage employees of certain subsidiaries. However, eligibility for the Company's plans has been frozen. Benefits for salaried employees under these plans are based primarily on years of service and employees' pay near retirement. Benefits for wage employees are based upon years of service and a fixed amount as periodically adjusted. The Company recognizes the years of service prior to the Company's acquisition of the subsidiary's facilities for purposes of determining vesting, eligibility and benefit levels for certain employees of the subsidiary and for determining vesting and eligibility for certain other employees of the subsidiary. The measurement date for these plans is December 31.

In December 2014, the Company announced a plan amendment to one of the Company's defined benefit pension plans. Under the plan amendment, no additional benefits may be earned by participants after January 31, 2015 and participants' accrued benefits will freeze at the levels earned as of January 31, 2015. In addition, the amendment added a lump sum payment option effective February 1, 2015. The Company made a similar plan amendment to another of its defined benefit pension plans in 2012. In conjunction with both of the defined benefit pension plans' amendments, the Company amended, in 2014 and 2012, its defined contribution savings plan to allow participants impacted by the amendments to participate in the Company's annual retirement contribution program.

In connection with the Merger, the Company assumed certain U.S. pension plans and other post-retirement benefit plans covering Axiall employees. The Axiall pension plans were closed to new participants and provide benefits to certain employees and retirees. The Axiall pension plans' assets and obligations merged into the Company's defined benefit pension plan for salaried employees during 2017. The other post-retirement benefit plans are unfunded and provide medical and life insurance benefits for certain employees and their dependents.

Non-U.S. Plans

The Company has defined benefit pension plans covering current and former employees associated with the Company's European operations. These pension plans are closed to new participants and are for employees in Germany who commenced employment before July 1, 2007. Benefits for employees for these plans are based primarily on employees' pay near retirement. These pension plans are unfunded and have no plan assets. In connection with the Merger, the Company assumed certain defined benefit pension plans. These pension plans are for employees outside of the U.S., namely in Canada and Taiwan. The measurement date for the non-U.S. plans is December 31.

Details of the changes in benefit obligations, plan assets and funded status of the Company's pension plans are as follows:



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Change in benefit obligation
Benefit obligation, beginning of year	$	799		$	125		$	62		$	95
Benefit obligation assumed with acquisition	—			—			818			21
Service cost	3			2			1			1
Interest cost	25			3			9			2
Actuarial loss (gain)	41			—			(74		)	13
Benefits paid	(45		)	(3		)	(17		)	(3		)
Settlements	(16		)	(1		)	—			—
Foreign exchange effects	—			16			—			(4		)
Benefit obligation, end of year	$	807		$	142		$	799		$	125

Change in plan assets
Fair value of plan assets, beginning of year	$	614		$	16		$	51		$	—
Acquisition	—			—			576			16
Actual return	97			1			7			—
Employer contribution	2			1			—			3
Benefits paid	(45		)	—			(17		)	(3		)
Administrative expenses paid	(2		)	—			(3		)	—
Settlements	(16		)	(1		)	—			—
Foreign exchange effects	—			1			—			—
Fair value of plan assets, end of year	$	650		$	18		$	614		$	16
Funded status, end of year	$	(157	)	$	(124	)	$	(185	)	$	(109	)



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Amounts recognized in the consolidated balance sheet at December 31
Current liabilities	$	(2	)	$	(3	)	$	(2	)	$	(2	)
Noncurrent liabilities	(155		)	(121		)	(183		)	(107		)
Net amount recognized	$	(157	)	$	(124	)	$	(185	)	$	(109	)



	2017					2016
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Amounts recognized in accumulated other comprehensive income (loss)
Net loss (gain)	$	(71	)	$	9	$	(53	)	$	8
Total before tax ⁽¹⁾	$	(71	)	$	9	$	(53	)	$	8

______________________________


(1)	After-tax totals for pension benefits were $43 and $30 for 2017 and 2016, respectively, and are reflected in stockholders' equity as accumulated other comprehensive income.

In the U.S., the Pension Protection Act of 2006 (the "Pension Protection Act") established a relationship between a qualified pension plan's funded status and the actual benefits that can be provided. Restrictions on plan benefits and additional funding and notice requirements are imposed when a plan's funded status is less than certain threshold levels. For the 2017 plan year, the funded status for the Company's U.S. pension plans are above 80% and, as such, are exempt from the Pension Protection Act's benefit restrictions.

Pension plans with an accumulated benefit obligation in excess of plan assets at December 31 are as follows:



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Information for pension plans with an accumulated benefit obligation in excess of plan assets
Projected benefit obligation	$	(807	)	$	(128	)	$	(799	)	$	(113	)
Accumulated benefit obligation	(807		)	(126		)	(799		)	(110		)
Fair value of plan assets	650			5			614			5

The following table provides the components of net periodic benefit costs, other changes in plan assets and benefit obligation recognized in other comprehensive income.



	Year Ended December 31,
	2017						2016					2015
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Components of net periodic benefit cost
Service cost	$	3		$	2		$	1		$	2	$	—		$	2
Administrative expenses	2			—			3			—		—			—
Interest cost	25			2			9			2		2			2
Expected return on plan assets	(40		)	(1		)	(15		)	—		(3		)	—
Net amortization	1			1			1			—		1			1
Settlement benefits	—			—			—			—		1			—
Net periodic benefit cost (gain)	$	(9	)	$	4		$	(1	)	$	4	$	1		$	5

Other changes in plan assets and benefit obligation recognized in other comprehensive income (OCI)
Net loss (gain) emerging	$	(18	)	$	—		$	(67	)	$	13	$	1		$	(17	)
Amortization of net loss	(1		)	(1		)	(1		)	—		(2		)	(1		)
Total recognized in OCI	$	(19	)	$	(1	)	$	(68	)	$	13	$	(1	)	$	(18	)
Total net periodic benefit cost and OCI	$	(28	)	$	3		$	(69	)	$	17	$	—		$	(13	)

The estimated prior service cost and net loss for the defined benefit plans that will be amortized from accumulated other comprehensive income into net periodic benefit cost during 2018 are expected to be $0 and $1, respectively.

The weighted-average assumptions used to determine pension plan obligations and net periodic benefit costs for the plans are as follows:



	2017				2016				2015
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans
Weighted average assumptions used to determine benefit obligations at December 31
Discount rate	3.4	%	1.8	%	3.8	%	1.8	%	4.0	%	2.4	%
Rate of compensation increase	—	%	2.6	%	—	%	2.6	%	—	%	2.5	%
Weighted average assumptions used to determine net periodic benefit costs for years ended December 31
Discount rate for benefit obligations	3.8	%	1.8	%	3.2	%	2.4	%	3.5	%	1.9	%
Discount rate for service cost	4.1	%	1.9	%	3.4	%	2.4	%	—	%	—	%
Discount rate for interest cost	3.2	%	2.0	%	2.9	%	2.4	%	—	%	—	%
Expected return on plan assets	6.8	%	3.8	%	6.8	%	4.6	%	7.0	%	—	%
Rate of compensation increase	N/A		2.6	%	—	%	2.6	%	—	%	2.5	%

The discount rates for the Company's U.S. and non-U.S. plans are determined using a benchmark pension discount curve and applying spot rates from the curve to each year of expected benefit payments to determine the appropriate discount rate for the Company.

The Company pension plans' investments are held in the Westlake U.S. Salaried Plan and the Westlake U.S. Wage Plan. The Company's overall investment strategy for its pension plan assets is to achieve a balance between moderate income generation and capital appreciation. The investment strategy includes a mix of approximately 60% of investments for long-term growth, and 40% for near-term benefit payments with a diversification of asset types. These pension funds' investment policies target asset allocations from approximately 60% equity securities and 40% fixed income securities in order to pursue a balance between moderate income generation and capital appreciation.

Equity securities primarily include investments in large-cap and small-cap companies located in the U.S. and international developed and emerging markets stocks. Fixed income securities are comprised of investment and non-investment grade bonds, including U.S. Treasuries and U.S. and non-U.S. corporate bonds of companies from diversified industries. Each pension fund investment policy allows a discretionary range in various asset classes within the asset allocation model of up to 10%. The Company does not believe that there are significant concentrations of risk in the pension plan assets due to its strategy of asset diversification. At December 31, 2017, plan assets did not include direct ownership of the Company's common stock.

Under the accounting guidance for fair value measurements, inputs used to measure fair value are classified in one of three levels:

Level 1: Quoted market prices in active markets for identical assets or liabilities.

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data.

Level 3: Unobservable inputs that are not corroborated by market data.

The investments in the collective trust and mutual funds are valued using a market approach based on the net asset value of units held. The fair values of the Company's U.S. plan assets at December 31, by asset category, are as follows:



	2017
	U.S. Plans						Non U.S. Plans
	Level 1		Level 2		Total		Level 1		Level 2		Total
Cash and common stock:
Cash and cash equivalents	$	—	$	—	$	—	$	5	$	—	$	5
Common stock	21		—		21		—		—		—
Collective investment trust and mutual funds—Equity securities:
Large-cap funds ⁽¹⁾	49		173		222		—		2		2
Small-cap funds ⁽²⁾	9		25		34		—		—		—
International funds ⁽³⁾	69		50		119		—		5		5
Collective investment trust and mutual funds—Fixed income:
Bond funds ⁽⁴⁾	116		125		241		—		6		6
Short-term investment funds	—		13		13		—		—		—
	$	264	$	386	$	650	$	5	$	13	$	18



	2016
	U.S. Plans						Non U.S. Plans
	Level 1		Level 2		Total		Level 1		Level 2		Total
Cash and common stock:
Cash and cash equivalents	$	—	$	—	$	—	$	5	$	—	$	5
Common stock	17		—		17		—		—		—
Collective investment trust and mutual funds—Equity securities:
Large-cap funds ⁽¹⁾	50		167		217		—		2		2
Small-cap funds ⁽²⁾	8		23		31		—		—		—
International funds ⁽³⁾	53		54		107		—		4		4
Collective investment trust and mutual funds—Fixed income:
Bond funds ⁽⁴⁾	62		165		227		—		5		5
Short-term investment funds	—		15		15		—		—		—
	$	190	$	424	$	614	$	5	$	11	$	16

______________________________


(1)	Substantially all of the assets of these funds are invested in large-cap U.S. companies. The remainder of the assets of these funds is invested in cash reserves.


(2)	Substantially all of the assets of these funds are invested in small-cap U.S. companies. The remainder of the assets of these funds is invested in cash reserves.


(3)	Substantially all of the assets of these funds are invested in international companies in developed markets (excluding the U.S.). The remainder of the assets of these funds is invested in cash reserves.


(4)	This category represents investment grade bonds of U.S. issuers, including U.S. Treasury notes.

The Company's funding policy for its U.S. plans is consistent with the minimum funding requirements of federal law and regulations, and based on preliminary estimates, the Company expects to make contributions of approximately $3 for the pension plans in 2018.

Multi-employer Plans

Non-U.S. Plans

The Company participates in two multi-employer plans, Pensionskasse der Mitarbeiter der Hoechst-Gruppe VVaG and Pensionskasse der Wacker-Chemie GmbH VVaG, which provide benefits to certain of the Company's employees in Germany. These multi-employer plans are closed to new participants. The benefit obligations are covered up to a certain salary threshold by contributions made by the Company and employees to the plans.

Contributions to the Company's multi-employer plans are expensed as incurred and were as follows:



	Year Ended December 31,
	2017		2016		2015
	Non-U.S. Plans		Non-U.S. Plans		Non-U.S. Plans
Contributions to multi-employer plans ⁽¹⁾	$	8	$	5	$	4

______________________________

(1)

The plan information for both the Pensionskasse der Mitarbeiter der Hoechst-Gruppe VVaG and Pensionskasse der Wacker-Chemie GmbH VVaG plans is publicly available. The plans provide fixed, monthly retirement payments on the basis of the credits earned by the participating employees. To the extent that the plans are underfunded, future contributions to the plans may increase and may be used to fund retirement benefits for employees related to other employers. The Company does not consider either of its multi-employer plans individually significant.

Other Post-retirement Benefits

In the U.S., the Company provides post-retirement healthcare benefits to the employees of two subsidiaries who meet certain minimum age and service requirements. The Company has the right to modify or terminate some of these benefits.

In conjunction with the Axiall acquisition, the Company assumed post-retirement plans in the U.S. and Canada which are unfunded and provide medical and life insurance benefits for certain employees and their dependents.

The following table provides a reconciliation of the benefit obligations of the Company's unfunded post-retirement healthcare plans.



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Change in benefit obligation
Benefit obligation, beginning of year	$	80		$	3		$	18		$	—
Benefit obligation assumed with acquisition	—			—			69			3
Service cost	1			—			—			—
Interest cost	2			—			1			—
Actuarial loss (gain)	(1		)	—			(6		)	—
Benefits paid	(9		)	—			(2		)	—
Benefit obligation, end of year	$	73		$	3		$	80		$	3

Change in plan assets
Fair value of plan assets, beginning of year	$	—		$	—		$	—		$	—
Employer contribution	9			—			2			—
Plan participants' contributions	—			—			—			—
Benefits paid	(9		)	—			(2		)	—
Fair value of plan assets, end of year	$	—		$	—		$	—		$	—
Funded status, end of year	$	(73	)	$	(3	)	$	(80	)	$	(3	)



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Amounts recognized in the consolidated balance sheet at December 31
Current liabilities	$	(8	)	$	—		$	(8	)	$	—
Noncurrent liabilities	(65		)	(3		)	(72		)	(3		)
Net amount recognized	$	(73	)	$	(3	)	$	(80	)	$	(3	)



	2017					2016
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Amounts recognized in accumulated other comprehensive income (loss)
Net loss	$	(5	)	$	—	$	(4	)	$	—
Total before tax ⁽¹⁾	$	(5	)	$	—	$	(4	)	$	—

______________________________


(1)	After-tax totals for post-retirement healthcare benefits were a loss of $0 and $1 for 2017 and 2016, respectively, and are reflected in stockholders' equity as accumulated other comprehensive income (loss).

The following table provides the components of net periodic benefit costs, other changes in plan assets and benefit obligation recognized in other comprehensive income.



	Year Ended December 31,
	2017					2016					2015
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans
Components of net periodic benefit cost
Service cost	$	1		$	—	$	—		$	—	$	—
Interest cost	2			—		1			—		1
Net amortization	—			—		—			—		—
Net periodic benefit cost	$	3		$	—	$	1		$	—	$	1

Other changes in plan assets and benefit obligation recognized in OCI
Net loss (gain) emerging	$	(1	)	$	—	$	(6	)	$	—	$	(2	)
Total recognized in OCI	$	(1	)	$	—	$	(6	)	$	—	$	(2	)
Total net periodic benefit cost and OCI	$	2		$	—	$	(5	)	$	—	$	(1	)

The estimated prior service cost and net loss for the post-retirement healthcare benefit plans that will be amortized from accumulated other comprehensive income into net periodic benefit cost during 2018 are both expected to be zero.

The weighted-average assumptions used to determine post-retirement healthcare plan obligations and net periodic benefit costs for the plans are as follows:



	2017				2016				2015
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans		U.S. Plans
Weighted average assumptions used to determine benefit obligations at December 31
Discount rate	3.0	%	4.0	%	3.3	%	4.0	%	3.5	%
Health care cost trend rate
- Initial rate	7.3	%	6.2	%	7.3	%	6.2	%	—	%
- Ultimate rate	4.5	%	4.5	%	4.5	%	4.5	%	—	%
- Years to ultimate	11		12		11		12		0
Weighted average assumptions used to determine net periodic benefit costs for years ended December 31
Discount rate for benefit obligations	3.3	%	3.3	%	2.6	%	3.3	%	3.3	%
Discount rate for service cost	3.8	%	3.3	%	3.1	%	3.3	%	—	%
Discount rate for interest cost	2.6	%	3.3	%	2.8	%	3.3	%	—	%
Health care cost trend rate
- Initial rate	6.8	%	6.8	%	7.0	%	6.8	%	—	%
- Ultimate rate	4.6	%	4.5	%	4.5	%	4.5	%	—	%
- Years to ultimate	11		12		12		13		0

The discount rate is determined using a benchmark pension discount curve and applying spot rates from the curve to each year of expected benefit payments to determine the appropriate discount rate for the Company. A one percentage-point increase or decrease in assumed healthcare trend rates would not have a significant effect on the amounts reported for the healthcare plans.

Estimated Future Benefit Payments

The following benefit payments are expected to be paid:



	Pension Benefits		Other Post- retirement Benefits
Estimated future benefit payments:
Year 1	$	51	$	8
Year 2	53		8
Year 3	52		8
Year 4	52		8
Year 5	53		8
Years 6 to 10	265		30

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Share-based Compensation [Abstract]

Stock-Based Compensation

Under the Westlake Chemical Corporation 2013 Omnibus Incentive Plan (as amended and restated, the "2013 Plan"), all employees and non-employee directors of the Company, as well as certain individuals who have agreed to become the Company's employees, are eligible for awards. Shares of common stock may be issued as authorized in the 2013 Plan. At the discretion of the administrator of the 2013 Plan, employees and non-employee directors may be granted awards in the form of stock options, stock appreciation rights, stock awards, restricted stock units or cash awards (any of which may be a performance award). Outstanding stock option awards have a 10-year term and vest either (1) ratably on an annual basis over a one to four-year period or (2) at the end of a five to 9.5-year period. Outstanding restricted stock units vest either (1) ratably on an annual basis over a three-year period or (2) at the end of a one to six-year period. In accordance with accounting guidance related to share-based payments, stock-based compensation expense for all stock-based compensation awards is based on estimated grant-date fair value. The Company recognizes these stock-based compensation costs net of a forfeiture rate and on a straight-line basis over the requisite service period of the award for only those shares expected to vest. For the years ended December 31, 2017, 2016 and 2015, the total recognized stock-based compensation expense related to equity awards issued under the 2013 Plan was $14, $14 and $10, respectively.

Option activity and changes during the year ended December 31, 2017 were as follows:



	Options		Weighted Average Exercise Price		Weighted Average Remaining Term (Years)	Aggregate Intrinsic Value
Outstanding at December 31, 2016	1,404,734		$	33.76
Granted	289,553		61.87
Exercised	(401,505	)	29.68
Cancelled	(23,181	)	56.92
Outstanding at December 31, 2017	1,269,601		$	41.04	5.9	$	83
Exercisable at December 31, 2017	719,676		$	28.89	3.9	$	56

For options outstanding at December 31, 2017, the options had the following range of exercise prices:



Range of Prices	Options Outstanding	Weighted Average Remaining Contractual Life (Years)
$7.12 - $9.65	300,366	1.6
$10.26 - $18.05	167,582	3.6
$22.92 - $30.05	316,601	7.6
$40.38 - $52.35	285,553	9.1
$61.87 - $68.18	199,499	6.8

The aggregate intrinsic value in the table above represents the total pretax intrinsic value (the difference between the Company's closing stock price on the last trading day of the year and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on December 31, 2017. This amount changes based on the fair market value of the Company's common stock. For the years ended December 31, 2017, 2016 and 2015, the total intrinsic value of options exercised was $24, $4 and $1, respectively.

As of December 31, 2017, $4 of total unrecognized compensation cost related to stock options is expected to be recognized over a weighted-average period of 1.4 years. Income tax benefits of $8, $1 and $0 were realized from the exercise of stock options during the years ended December 31, 2017, 2016 and 2015, respectively.

The Company used the Black-Scholes option pricing model to value its options. The table below presents the weighted average value and assumptions used in determining each option's fair value. Volatility was calculated using historical trends of the Company's common stock price.



	Stock Option Grants
	Year Ended December 31,
	2017			2016			2015
Weighted average fair value	$	15.84		$	11.67		$	20.21
Risk-free interest rate	2.1		%	1.4		%	1.7		%
Expected life in years	5			5			5
Expected volatility	29.2		%	32.9		%	34.2		%
Expected dividend yield	1.2		%	1.6		%	0.9		%

The Company had no non-vested restricted stock awards as of December 31, 2017 and 2016. As of December 31, 2017, there was no unrecognized stock-based compensation expense related to non-vested restricted stock awards. The total fair value of restricted stock awards that vested during the years ended December 31, 2017, 2016 and 2015 was $0, $4 and $8, respectively.

Non-vested restricted stock units as of December 31, 2017 and changes during the year ended December 31, 2017 were as follows:



	Number of Units		Weighted Average Grant Date Fair Value
Non-vested at December 31, 2016	597,559		$	55.64
Granted	198,659		62.46
Vested	(91,997	)	61.39
Forfeited	(40,355	)	56.08
Non-vested at December 31, 2017	663,866		$	56.86

As of December 31, 2017, there was $17 of unrecognized stock-based compensation expense related to non-vested restricted stock units. This cost is expected to be recognized over a weighted-average period of 1.6 years. The total fair value of restricted stock units that vested during the years ended December 31, 2017, 2016 and 2015 was $6, $4 and $1, respectively.

Axiall Awards Assumed in the Merger

In the Merger, all outstanding Axiall restricted stock units were assumed by the Company and converted into restricted stock units in respect of the Company's common stock, with the same terms and conditions except that upon settlement the award holders will receive the greater of (1) the value of $33.00 per Axiall restricted stock unit that was converted into a restricted stock unit in respect of the Company's common stock and (2) the value of the Company's common stock. The awards are classified as liability awards for accounting purposes and are re-measured at each reporting date until they vest. The portion of the replacement award that is attributable to pre-combination service by the employee was included in the measure of consideration transferred to acquire Axiall. The remaining fair value of the replacement awards will be recognized as stock-based compensation expense over the remaining vesting period. Total stock-based compensation expense recognized related to Axiall restricted stock units that were assumed by the Company and converted into restricted stock units during the years ended December 31, 2017 and 2016 was $9 and $38, respectively, of which $33 was included in transaction and integration-related costs in the consolidated statement of operations during the year ended December 31, 2016.

The Company estimates the fair value of these awards using the Company's common stock price and a pricing model to estimate the value attributable to the $33.00 minimum price per Axiall restricted stock unit converted into a restricted stock unit in respect of the Company's common stock. The table below presents the assumptions used in determining each liability classified restricted stock unit's fair value. Volatility was calculated using historical trends of the Company's common stock price.



	Liability Classified Restricted Stock Awards
	Year Ended December 31, 2017
Weighted average vesting period in years	0.8
Risk-free interest rate	1.6	%
Expected volatility	23.1	%
Expected dividend yield	0.8	%

Non-vested liability classified restricted stock awards as of December 31, 2017 and changes during the year ended December 31, 2017 were as follows:



	Number of Units		Weighted Average Fair Value
Non-vested at December 31, 2016	286,147		$	60.77
Vested	(161,324	)	65.29
Cancelled	(23,831	)	66.97
Non-vested at December 31, 2017	100,992		$	106.53

As of December 31, 2017, there was $5 of unrecognized stock-based compensation expense related to non-vested liability classified restricted stock awards. The total fair value of liability classified restricted stock awards that vested during the years ended December 31, 2017 and 2016 was $11 and $3, respectively. The total fair value of liability classified restricted stock awards cancelled during the year ended December 31, 2017 was $2.

Westlake Chemical Partners LP Awards

The Company's wholly-owned subsidiary and the general partner of Westlake Partners, Westlake Chemical Partners GP LLC ("WLKP GP"), maintains a unit-based compensation plan for directors and employees of WLKP GP and Westlake Partners.

The Westlake Partners 2014 Long-term Incentive Plan ("Westlake Partners 2014 Plan") permits various types of equity awards including but not limited to grants of phantom units and restricted units. Awards granted under the Westlake Partners 2014 Plan may be settled with Westlake Partners units or in cash or a combination thereof. Compensation expense for these awards was not material to the Company's consolidated financial statements for the years ended December 31, 2017, 2016 and 2015.

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Company has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts payable and long-term debt, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for cash and cash equivalents, accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of the Company's long-term debt (including the current portion of long-term debt) at December 31, 2017 and 2016 are summarized in the table below. The Company's long-term debt instruments are publicly-traded. A market approach, based upon quotes from financial reporting services, is used to measure the fair value of the Company's long-term debt. Because the Company's long-term debt instruments may not be actively traded, the inputs used to measure the fair value of the Company's long-term debt are classified as Level 2 inputs within the fair value hierarchy.



	2017				2016
	Carrying Value		Fair Value		Carrying Value		Fair Value
Revolving credit facility	$	—	$	—	$	325	$	325
4.625% Westlake 2021 Senior Notes ⁽¹⁾	645		639		652		651
4.625% Subsidiary 2021 Senior Notes ⁽¹⁾	65		65		66		66
3.60% 2022 Senior Notes	249		255		248		252
4.875% Westlake 2023 Senior Notes	445		449		447		451
4.875% Subsidiary 2023 Senior Notes	16		16		17		17
3.60% 2026 Senior Notes	740		757		739		722
Loan related to tax-exempt waste disposal revenue bonds due 2027	11		11		11		11
6 ½% 2029 GO Zone Senior Notes	99		111		99		112
6 ¾% 2032 GO Zone Senior Notes	—		—		248		259
6 ½% 2035 GO Zone Senior Notes	88		99		88		100
6 ½% 2035 IKE Zone Senior Notes	65		74		65		73
5.0% 2046 Senior Notes	675		787		674		692
4.375% 2047 Senior Notes	491		518		—		—
3.50% 2032 Senior Notes	248		256		—		—

___________________________


(1)	The 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes were classified as a component of current liabilities in the consolidated balance sheet at December 31, 2017. For additional information, see Note 9.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

On December 22, 2017, the U.S. Tax Cuts and Jobs Act (the "Tax Act") was signed into law. The Tax Act, among other changes, reduces U.S. corporate income tax rate from 35% to 21%, effective January 1, 2018, and also requires a one-time deemed repatriation of foreign earnings at specified rates. The corporate income tax rate change resulted in a revaluation of the Company's deferred tax assets and liabilities. The accounting guidance on income taxes requires that the effect on deferred tax assets and liabilities of a change in tax rates be recognized in the period the tax rate change was enacted. The SEC staff guidance allows registrants to record provisional amounts during a measurement period when it does not have the necessary information available, prepared or analyzed (including computations) in reasonable detail to complete its accounting for the change in tax law. The measurement period ends when a company has obtained, prepared and analyzed the information necessary to finalize its accounting, but cannot extend beyond one year. Under the above guidance, the Company made a provisional adjustment of $591 of income tax benefit in the 2017 consolidated financial statements for items that the Company could reasonably estimate such as revaluation of deferred tax assets and liabilities and a one-time U.S. tax on the mandatory deemed repatriation of the Company's post-1986 foreign earnings. The Company will continue to assess the income tax effects of the Tax Act based on further standard setting activities, any transition provisions, and changes in the facts and circumstances of the Company's tax position, during the measurement period.

The components of income before income taxes are as follows:



	Year Ended December 31,
	2017		2016		2015
Domestic	$	917	$	476	$	880
Foreign	164		82		83
	$	1,081	$	558	$	963

The Company's provision for (benefit from) income taxes consists of the following:



	Year Ended December 31,
	2017			2016			2015
Current
Federal	$	231		$	8		$	225
State	18			9			24
Foreign	27			20			9
	276			37			258
Deferred
Federal	(557		)	136			30
State	25			(33		)	3
Foreign	(2		)	(2		)	7
	(534		)	101			40
Total provision for (benefit from) income taxes	$	(258	)	$	138		$	298

A reconciliation of taxes computed at the statutory rate to the Company's income tax expense is as follows:



	Year Ended December 31,
	2017			2016			2015
Provision for federal income tax, at statutory rate	$	378		$	195		$	337
State income tax provision, net of federal income tax effect	26			1			17
Foreign income tax rate differential	(33		)	(8		)	(13		)
Manufacturing deduction	(23		)	(2		)	(24		)
Depletion	(7		)	(2		)	—
Noncontrolling interests	(9		)	(7		)	(7		)
Tax on previously held shares of Axiall Corporation and certain other acquisition related items	—			(13		)	—
Tax Act related adjustment	(591		)	—			—
Changes in state apportionment and other state adjustments	2			(17		)	—
Research and development expenditures and adjustments related to prior years' tax returns	(1		)	(8		)	—
Other, net	—			(1		)	(12		)
	$	(258	)	$	138		$	298

The tax effects of the principal temporary differences between financial reporting and income tax reporting at December 31 are as follows:



	2017			2016
Net operating loss carryforward	$	64		$	70
Credit carryforward	26			24
Accruals	53			67
Pension	79			114
Allowance for doubtful accounts	5			12
Inventories	11			13
Other	15			36
Deferred taxes assets—total	253			336
Property, plant and equipment	(906		)	(1,374		)
Intangibles	(154		)	(221		)
Turnaround costs	(8		)	(1		)
Basis difference—consolidated partnerships	(209		)	(308		)
Other	(18		)	(17		)
Deferred tax liabilities—total	(1,295		)	(1,921		)
Valuation allowance	(56		)	(53		)
Total net deferred tax liabilities	$	(1,098	)	$	(1,638	)

Balance sheet classifications
Noncurrent deferred tax asset	$	13		$	12
Noncurrent deferred tax liability	(1,111		)	(1,650		)
Total net deferred tax liabilities	$	(1,098	)	$	(1,638	)

At December 31, 2017, the Company had foreign and state net operating loss carryforwards of approximately $405, which will expire in varying amounts between 2018 and 2037 and are subject to certain limitations on an annual basis. Management believes the Company will realize the benefit of a portion of the net operating loss carryforwards before they expire, but to the extent that the full benefit may not be realized, a valuation allowance has been recorded. The valuation allowance increased by $3 in 2017 mostly as a result of the revaluation of the Company's deferred tax assets.

The Tax Act requires a one-time U.S. tax at a specified rate for a mandatory deemed repatriation of post-1986 foreign earnings. For the quarter ended December 31, 2017, the Company recorded, on a provisional basis, approximately $5 of U.S. tax expense related to this one-time repatriation tax and elected to pay the tax over eight years as allowed by the Tax Act.

For the year ended December 31, 2017, the Company accrued $7 of foreign tax as it is no longer permanently reinvested with respect to the outside basis difference for all of its foreign subsidiaries.

The Company files income tax returns in the U.S. federal jurisdiction, various states and foreign jurisdictions. The Company is no longer subject to examinations by tax authorities before the year 2011.

Earnings per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings per Share

The Company has unvested restricted stock units outstanding that are considered participating securities and, therefore, computes basic and diluted earnings per share under the two-class method. Basic earnings per share for the periods are based upon the weighted average number of shares of common stock outstanding during the periods. Diluted earnings per share include the effect of certain stock options.



	Year Ended December 31,
	2017			2016			2015
Net income attributable to Westlake Chemical Corporation	$	1,304		$	399		$	646
Less:
Net income attributable to participating securities	(7		)	(2		)	(3		)
Net income attributable to common shareholders	$	1,297		$	397		$	643

The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:



	Year Ended December 31,
	2017		2016		2015
Weighted average common shares—basic	129,087,043		129,367,712		131,823,707
Plus incremental shares from:
Assumed exercise of options	452,970		607,110		478,105
Weighted average common shares—diluted	129,540,013		129,974,822		132,301,812

Earnings per common share attributable to Westlake Chemical Corporation:
Basic	$	10.05	$	3.07	$	4.88
Diluted	$	10.00	$	3.06	$	4.86

There are no antidilutive options to purchase shares of common stock for the year ended December 31, 2017. Excluded from the computation of diluted earnings per share for the years ended December 31, 2016 and 2015 are options to purchase 318,259 and 301,969 shares of common stock, respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive.

Supplemental Information

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Supplemental Information

Accrued Liabilities

Accrued liabilities were $657 and $538 at December 31, 2017 and 2016, respectively. Accrued rebates and accrued income taxes, which are components of accrued liabilities, were $108 and $130, respectively, at December 31, 2017 and $78 and $11 at December 31, 2016, respectively. No other component of accrued liabilities was more than five percent of total current liabilities.

Non-cash Investing Activity

The change in capital expenditure accruals reducing additions to property, plant and equipment was $9 and $7 for the years ended December 31, 2017 and 2015, respectively. The change in capital expenditure accruals increasing additions to property, plant and equipment was $7 for the year ended December 31, 2016.

Other Income, Net

Other income, net included a $49 gain realized on previously held shares of Axiall common stock for the year ended December 31, 2016 and a $21 gain on acquisition and related expenses, net on the acquisition of Huasu for the year ended December 31, 2015. No other components of other income, net were material to the statements of operations for the years ended December 31, 2017, 2016 and 2015.

Cash Flow Information



	Year Ended December 31,
	2017		2016		2015
Cash paid for:
Interest paid, net of interest capitalized	$	154	$	46	$	32
Income taxes paid	84		3		314

Related Party And Affiliate Transactions	12 Months Ended
Related Party And Affiliate Transactions	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party And Affiliate Transactions	Related Party and Affiliate Transactions The Company leases office space for management and administrative services from an affiliate of the Company's principal stockholder. For the years ended December 31, 2017, 2016 and 2015, the Company incurred lease payments of approximately $3, $3 and $2, respectively. Cypress Interstate Pipeline L.L.C., a natural gas liquids pipeline joint venture company in which the Company owns a 50% equity stake, transports natural gas liquid feedstocks to the Company's Lake Charles complex through its pipeline. The Company accounts for its investments in Cypress Interstate Pipeline L.L.C. under the equity method of accounting. The investment in Cypress Interstate Pipeline L.L.C. at December 31, 2017 and 2016 was $9 and $9, respectively. For the years ended December 31, 2017, 2016 and 2015, the Company incurred pipeline fees of approximately $15, $14 and $14, respectively, payable to this joint venture for usage of the pipeline. The amounts due to this joint venture were $1 and $1 at December 31, 2017 and 2016, respectively. EPS Ethylene Pipeline Süd GmbH & Co. KG, an ethylene pipeline company in which the Company owns a 10% equity stake, transports ethylene feedstocks to the Company's Gendorf, Germany production facility through its pipeline. For the years ended December 31, 2017, 2016 and 2015, the Company incurred pipeline fees of approximately $0, $1 and $1, respectively, for usage of the pipeline. There were no outstanding amounts due to this related party at December 31, 2017 and 2016. The Company owns a 15% and an 11% equity stake in InfraServ Knapsack GmbH & Co. KG and InfraServ Gendorf GmbH & Co. KG, respectively. The Company has service agreements with these entities, including contracts to provide electricity and technical services to certain of the Company's production facilities in Germany. The investment in Infraserv was $56 and $50 at December 31, 2017 and 2016, respectively. For the years ended December 31, 2017, 2016 and 2015, the Company incurred charges aggregating approximately $133, $131 and $116, respectively, for these services. The amounts accrued for these related parties were approximately $33 and $25 at December 31, 2017 and 2016, respectively. The Company owns a 50% interest in Shriram Axiall Private Limited ("SAPL"), which the Company acquired as a result of the Merger. SAPL is a joint venture formed in April 2014 to facilitate the manufacture and sale of certain compound products in India. The Company accounts for its investments in SAPL under the equity method of accounting. The investment in SAPL at December 31, 2017 and 2016 was $0 and $2, respectively. The Company owns a 50% interest in RS Cogen LLC ("RS Cogen"), which the Company acquired as a result of the Merger. RS Cogen operates a process steam, natural gas-fired cogeneration facility adjacent to the Lake Charles South Facility. The Company accounts for its investment in RS Cogen under the equity method of accounting. The investment in RS Cogen at December 31, 2017 and 2016 was $10 and $10, respectively. For the year ended December 31, 2017 and for the period from August 31, 2016 to December 31, 2016, the Company recorded purchases of approximately $26 and $9 from RS Cogen, respectively. The amount payable to this related party was approximately $2 and $1 at December 31, 2017 and 2016, respectively. The Company owns a 50% interest in Vinyl Solutions, LLC ("Vinyl Solutions"), which the Company acquired as a result of the Merger. The Company accounts for its investments in Vinyl Solutions under the equity method of accounting. Vinyl Solutions is a compounding manufacturer of specialty compounds. For the year ended December 31, 2017 and for the period from August 31, 2016 to December 31, 2016, the Company recorded sales of $17 and $6, respectively, to Vinyl Solutions. The amount receivable from this related party was $7 and $5 at December 31, 2017 and 2016, respectively. On June 17, 2015, Eagle US 2 LLC ("Eagle"), a wholly-owned subsidiary of Axiall, entered into an amended and restated limited liability company agreement with Lotte Chemical USA Corporation ("Lotte") related to the formation of LACC, LLC ("LACC"), which was formed by Eagle and Lotte to design, build and operate a 1 billion ton per year ethylene plant. Pursuant to a contribution and subscription agreement, dated as of June 17, 2015, between Eagle and LACC, Eagle has agreed to make a maximum capital commitment to LACC of up to $225 to fund the construction costs of the plant, representing a 10% interest in LACC. Eagle and Lotte also entered into a call option agreement, dated as of June 17, 2015, pursuant to which Eagle has the right, but not the obligation, until the third anniversary of the substantial completion of the plant, to acquire up to a 50% ownership interest in LACC from Lotte. The construction of the plant commenced in January 2016. The plant is being built adjacent to the Company's largest chlor-alkali chemical facility, located in Lake Charles, to take advantage of the Company's existing infrastructure, access to competitive feedstock resources and ethylene distribution infrastructure. The anticipated start-up for the plant is expected to be in the first quarter of 2019. The Company acquired this investment as a result of the Merger. As of December 31, 2017 and 2016, the Company's investment in LACC was $125 and $59, respectively. Total funding by the Company in LACC for the year ended December 31, 2017 and for the period from August 31, 2016 to December 31, 2016 amounted to $66 and $17, respectively. The amount receivable from LACC at December 31, 2017 and 2016 was approximately $0 and $1, respectively. The Company's investment in LACC is accounted for under the cost method. Dividends received from equity method investments were $6, $5 and $6 for the years ended December 31, 2017, 2016 and 2015, respectively. One of the Company's directors serves as Chairman and Chief Executive Officer of American Air Liquide Holdings, Inc. and as a Senior Vice President of the Air Liquide Group ("Air Liquide"). The Company purchased oxygen, nitrogen and utilities and leased cylinders from various affiliates of American Air Liquide Holdings, Inc. including Airgas and subsidiaries that were acquired in 2016 by Air Liquide aggregating approximately $30, $22 and $10 for the years ended December 31, 2017, 2016 and 2015, respectively. The Company also sold certain utilities to Air Liquide aggregating approximately $7 and $4 during the years ended December 31, 2017 and 2016, respectively. The amount payable to Air Liquide was $2 and $4 at December 31, 2017 and 2016, respectively, and the amount receivable from Air Liquide was $1 and $1 at December 31, 2017 and 2016, respectively.

Westlake Chemical Partners LP	12 Months Ended
Westlake Chemical Partners LP	Dec. 31, 2017
Equity [Abstract]
Westlake Chemical Partners LP	Westlake Chemical Partners LP On August 4, 2014, Westlake Partners completed its initial public offering (the "IPO") of 12,937,500 common units at a price of $24.00 per unit. Net proceeds to Westlake Partners from the sale of the units was approximately $286, net of underwriting discounts, structuring fees and offering expenses of approximately $24. At the consummation of the IPO, Westlake Partners' assets consisted of a 10.6% limited partner interest in OpCo, as well as the general partner interest in OpCo. Immediately after the IPO, the Company retained an 89.4% limited partner interest in OpCo and a significant interest in Westlake Partners. The IPO represented the sale of 47.8% of the common units in Westlake Partners. Westlake Partners purchased additional 2.7% and 5.0% newly-issued limited partner interests in OpCo on April 29, 2015 and on September 29, 2017, respectively. On September 29, 2017, Westlake Partners completed a secondary offering of 5,175,000 common units at a price of $22.00 per unit. Net proceeds to Westlake Partners from the sale of the units were $111, net of underwriting discounts, structuring fees and estimated offering expenses of approximately $3. At December 31, 2017, Westlake Partners had a 18.3% limited partner interest in OpCo, and the Company retained an 81.7% limited partner interest in OpCo and a significant interest in Westlake Partners.

Commitments And Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments And Contingencies

Commitments and Contingencies

The Company is involved in a number of legal and regulatory matters, principally environmental in nature, that are incidental to the normal conduct of its business, including lawsuits, investigations and claims. The outcome of these matters are inherently unpredictable. The Company believes that, in the aggregate, the outcome of all known legal and regulatory matters will not have a material adverse effect on its consolidated financial statements; however, specific outcomes with respect to such matters may be material to the Company's consolidated statements of operations in any particular period in which costs, if any, are recognized. The Company's assessment of the potential impact of environmental matters, in particular, is subject to uncertainty due to the complex, ongoing and evolving process of investigation and remediation of such environmental matters, and the potential for technological and regulatory developments. In addition, the impact of evolving claims and programs, such as natural resource damage claims, industrial site reuse initiatives and state remediation programs creates further uncertainty of the ultimate resolution of these matters. The Company anticipates that the resolution of many legal and regulatory matters, and in particular environmental matters, will occur over an extended period of time.

Environmental. As of December 31, 2017 and 2016, the Company had reserves for environmental contingencies totaling approximately $49 and $49, respectively, most of which was classified as noncurrent liabilities. The Company's assessment of the potential impact of these environmental contingencies is subject to considerable uncertainty due to the complex, ongoing and evolving process of investigation and remediation, if necessary, of such environmental contingencies, and the potential for technological and regulatory developments.

Calvert City Proceedings. For several years, the Environmental Protection Agency (the "EPA") has been conducting remedial investigation and feasibility studies at the Company's Calvert City, Kentucky facility pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). As the current owner of the Calvert City facility, the Company was named by the EPA as a potentially responsible party ("PRP") along with Goodrich Corporation ("Goodrich") and its successor-in-interest, PolyOne Corporation ("PolyOne"). On November 30, 2017, the EPA published a draft Proposed Plan, incorporating by reference an August 2015 draft Remedial Investigation (RI) report, an October 2017 draft Feasibility Study (FS) report and a new Technical Impracticability Waiver document dated December 19, 2017. The draft Proposed Plan describes a preferred remedy that includes a containment wall with targeted treatment and supplemental hydraulic containment, as well as active treatment of historical groundwater contamination under the Tennessee River. The EPA has estimated that the total remedy will cost $200 to $250 with an estimated $1 to $3 in annual operation and maintenance (O&M) costs. The Company's allocation of liability for remedial or O&M costs, if any, will be determined by the outcome of the contractual dispute with Goodrich/PolyOne, which is the subject of a pending arbitration proceeding as described below.

In connection with the 1990 and 1997 acquisitions of the Goodrich chemical manufacturing complex in Calvert City, Goodrich agreed to indemnify the Company for any liabilities related to preexisting contamination at the complex. For its part, the Company agreed to indemnify Goodrich for post-closing contamination caused by the Company's operations. The soil and groundwater at the complex, which does not include the Company's nearby PVC facility, had been extensively contaminated by Goodrich's operations. In 1993, Goodrich spun off the predecessor of PolyOne, and that predecessor assumed Goodrich's indemnification obligations relating to preexisting contamination. In 2003, litigation arose among the Company, Goodrich and PolyOne with respect to the allocation of the cost of remediating contamination at the site. The parties settled this litigation in December 2007 and the case was dismissed. In the settlement, the parties agreed that, among other things: (1) PolyOne would pay 100% of the costs (with specified exceptions), net of recoveries or credits from third parties, incurred with respect to environmental issues at the Calvert City site from August 1, 2007 forward; and (2) either the Company or PolyOne might, from time to time in the future (but not more than once every five years), institute an arbitration proceeding to adjust that percentage. In May 2017, PolyOne filed a demand for arbitration. In this proceeding, PolyOne seeks to readjust the percentage allocation of costs and to recover approximately $17 from the Company in reimbursement of previously paid remediation costs. The Company filed a cross demand for arbitration seeking $6 in unreimbursed remediation costs incurred during the relevant period.

On October 6, 2017, PolyOne filed suit against the Company in the U.S. District Court for the Western District of Kentucky seeking for the court — instead of the arbitration panel — to resolve claims asserted by the Company in the arbitration proceedings related to reimbursement of costs incurred by the Company at the Calvert City complex. PolyOne is seeking a declaratory judgment from the court that costs claimed by the Company in the arbitration are not covered under the 2007 settlement agreement and thus are not within the jurisdiction of the arbitration panel. In response, the Company has filed a motion to dismiss asserting that PolyOne's jurisdictional claims are unfounded and that the arbitration panel has jurisdiction over Westlake's claims for cost reimbursement under the arbitration agreement contained within the 2007 settlement agreement.

At this time, since the proceedings are in an early stage, the Company is not able to estimate the impact, if any, that the arbitration proceeding could have on the Company's consolidated financial statements in 2017 and later years. Any cash expenditures that the Company might incur in the future with respect to the remediation of contamination at the Calvert City complex would likely be spread out over an extended period. As a result, the Company believes it is unlikely that any remediation costs allocable to it will be material in terms of expenditures made in any individual reporting period.

Environmental Remediation: Reasonably Possible Matters. The Company's assessment of the potential impact of environmental contingencies is subject to considerable uncertainty due to the complex, ongoing and evolving process of investigation and remediation, if necessary, of such environmental contingencies, and the potential for technological and regulatory developments. As such, in addition to the amounts currently reserved, the Company may be subject to reasonably possible loss contingencies related to environmental matters in the range of $55 to $110.

Other Commitments

The Company is obligated under various long-term and short-term noncancelable operating leases, primarily related to rail car leases and land. Several of the leases provide for renewal terms and, in certain leases, purchase options. At December 31, 2017, future minimum lease commitments for operating lease obligations and capital lease obligations were as follows:



	Operating Leases		Capital Leases
2018	$	108	$	3
2019	97		3
2020	73		3
2021	56		2
2022	44		2
Thereafter	651		9
Total minimum lease payments	$	1,029	$	22
Less: Imputed interest costs			(12		)
Present value of net minimum lease payments			$	10

Operating lease rental expense was approximately $147, $87 and $69 for the years ended December 31, 2017, 2016 and 2015, respectively.

The Company has various unconditional purchase obligations, primarily to purchase goods and services, including commitments to purchase various utilities, feedstock, nitrogen, oxygen, product storage and pipeline usage. Unrecorded unconditional purchase obligations for the next five years are as follows: $430, $412, $376, $330 and $95 in 2018, 2019, 2020, 2021 and 2022, respectively.

Segment And Geographic Information

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segment and Geographic Information

Segment Information

The Company operates in two principal operating segments: Olefins and Vinyls. These segments are strategic business units that offer a variety of different products. The Company manages each segment separately as each business requires different technology and marketing strategies.

The Company's Olefins segment manufactures and markets polyethylene, styrene monomer and various ethylene co-products. The Company's ethylene production is used in the Company's polyethylene, styrene and VCM operations. In addition, the Company sells ethylene and ethylene co-products, primarily propylene, crude butadiene, pyrolysis gasoline and hydrogen, to external customers.

No single customer accounted for more than 10% of sales in the Olefins segment for the years ended December 31, 2017, 2016 or 2015.

The Company's Vinyl segment manufactures and markets PVC, VCM, ethylene dichloride ("EDC"), chlor-alkali (chlorine and caustic soda), chlorinated derivative products and ethylene. The Company also manufactures and sells building products fabricated from PVC, including siding, pipe, fittings, profiles, trim, mouldings, fence and decking products, window and door components and film and sheet products. The Company's primary North American chemical manufacturing facilities are located in its Calvert City, Kentucky and Lake Charles, Plaquemine and Geismar, Louisiana sites. The Company also produces chlorine, caustic soda, hydrogen and chlorinated derivative products at its facilities in Natrium, Longview, Washington and Beauharnois, Quebec and PVC resin and PVC compounds at several facilities in Mississippi. In addition, the Company has manufacturing facilities in Germany, the United Kingdom, Taiwan and the People's Republic of China.

As of December 31, 2017, the Company owned 24 building products facilities. The Company uses its chlorine, VCM and PVC production to manufacture its building products. No single customer accounted for more than 10% of sales in the Vinyls segment for the years ended December 31, 2017, 2016 or 2015.

The accounting policies of the individual segments are the same as those described in Note 1.



	Year Ended December 31,
	2017			2016			2015
Net external sales
Olefins
Polyethylene	$	1,518		$	1,463		$	1,651
Styrene, feedstock and other	533			431			609
Total olefins	2,051			1,894			2,260
Vinyls
PVC, caustic soda and other	4,769			2,493			1,718
Building products	1,221			689			485
Total vinyls	5,990			3,182			2,203
	$	8,041		$	5,076		$	4,463

Intersegment sales
Olefins	$	393		$	165		$	107
Vinyls	1			26			1
	$	394		$	191		$	108

Income (loss) from operations
Olefins	$	655		$	558		$	747
Vinyls	647			174			255
Corporate and other	(69		)	(151		)	(42		)
	$	1,233		$	581		$	960

Depreciation and amortization
Olefins	$	145		$	136		$	111
Vinyls	449			238			134
Corporate and other	7			4			1
	$	601		$	378		$	246

Other income (expense), net
Olefins	$	3		$	5		$	5
Vinyls	(1		)	3			8
Corporate and other	5			48			25
	$	7		$	56		$	38

Provision for (benefit from) income taxes
Olefins	$	63		$	175		$	243
Vinyls	(302		)	25			64
Corporate and other	(19		)	(62		)	(9		)
	$	(258	)	$	138		$	298

Capital expenditures
Olefins	$	97		$	324		$	305
Vinyls	459			302			176
Corporate and other	21			3			10
	$	577		$	629		$	491



	December 31, 2017		December 31, 2016
Total assets
Olefins	$	2,006	$	2,093
Vinyls	8,853		8,287
Corporate and other	1,217		510
	$	12,076	$	10,890

A reconciliation of total segment income from operations to consolidated income before income taxes is as follows:



	Year Ended December 31,
	2017			2016			2015
Income from operations for reportable segments	$	1,233		$	581		$	960
Interest expense	(159		)	(79		)	(35		)
Other income, net	7			56			38
Income before income taxes	$	1,081		$	558		$	963

Geographic Information



	Year Ended December 31,
	2017		2016		2015
Sales to external customers ⁽¹⁾
United States	$	5,739	$	3,526	$	3,133
Foreign
Canada	653		317		196
Germany	432		402		394
Switzerland	142		101		107
Brazil	108		41		16
China	104		87		46
Italy	96		84		90
Taiwan	96		25		—
Other	671		493		481
	$	8,041	$	5,076	$	4,463



	December 31, 2017		December 31, 2016
Long-lived assets
United States	$	5,668	$	5,783
Foreign
Germany	504		401
Other	240		236
	$	6,412	$	6,420

______________________________


(1)	Revenues are attributed to countries based on location of customer.

Guarantor Disclosures

12 Months Ended

Dec. 31, 2017

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Guarantor Disclosures

The Company's payment obligations under the Senior Notes, 4.375% 2047 Senior Notes, 3.60% 2022 Senior Notes, the 3.60% 2026 Senior Notes, the 5.0% 2046 Senior Notes and the 4.875% Westlake 2023 Senior Notes are fully and unconditionally guaranteed by each of its current and future domestic subsidiaries that guarantee other debt of the Company or of another guarantor of those notes in excess of $5 (the "Guarantor Subsidiaries"). Each Guarantor Subsidiary is 100% owned by Westlake Chemical Corporation (the "100% Owned Guarantor Subsidiaries"). During 2016 and 2017, the Company executed a Joinder Agreement with the Administrative Agent of the Credit Agreement, whereby certain subsidiaries of the Company were added as Guarantor Subsidiaries. These guarantees are the joint and several obligations of the Guarantor Subsidiaries. The following condensed consolidating financial information presents the financial condition, results of operations and cash flows of Westlake Chemical Corporation, the 100% owned Guarantor Subsidiaries, and the remaining subsidiaries that do not guarantee the Senior Notes, the 4.375% 2047 Senior Notes, the 3.60% 2022 Senior Notes, the 3.60% 2026 Senior Notes, the 5.0% 2046 Senior Notes and the 4.875% Westlake 2023 Senior Notes (the "Non-Guarantor Subsidiaries"), together with consolidating eliminations necessary to present the Company's results on a consolidated basis.

In 2016, certain of the Company's subsidiary guarantors were released from their guarantees of the Company's 3.60% 2022 Senior Notes in connection with the replacement of the Company's revolving credit facility. Westlake Chemical OpCo LP, which was previously separately presented as a less than 100% owned guarantor, and certain of the Company's other 100% owned subsidiaries that were previously presented as guarantors, are now reflected as Non-Guarantor Subsidiaries in the condensed consolidating guarantor financial information. Prior periods were retrospectively adjusted to conform to the current presentation of Guarantor Subsidiaries and Non-Guarantor Subsidiaries.

ondensed Consolidating Financial Information as of December 31, 2017



	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	1,089	$	57	$	385	$	—		$	1,531
Accounts receivable, net	3,331		4,128		580		(7,038		)	1,001
Inventories	—		654		246		—			900
Prepaid expenses and other current assets	52		26		31		(79		)	30
Restricted cash	—		1		—		—			1
Total current assets	4,472		4,866		1,242		(7,117		)	3,463
Property, plant and equipment, net	—		4,374		2,038		—			6,412
Goodwill	—		855		157		—			1,012
Customer relationships, net	—		479		137		—			616
Other intangible assets, net	—		88		73		—			161
Other assets, net	10,706		798		1,271		(12,363		)	412
Total assets	$	15,178	$	11,460	$	4,918	$	(19,480	)	$	12,076
Current liabilities
Accounts payable	$	6,367	$	864	$	224	$	(6,855	)	$	600
Accrued liabilities	189		484		246		(262		)	657
Current portion of long-term debt, net	710		—		—		—			710
Total current liabilities	7,266		1,348		470		(7,117		)	1,967
Long-term debt, net	3,034		4,242		220		(4,369		)	3,127
Deferred income taxes	—		1,026		92		(7		)	1,111
Pension and other liabilities	4		347		151		—			502
Total liabilities	10,304		6,963		933		(11,493		)	6,707
Total Westlake Chemical Corporation stockholders' equity	4,874		4,497		3,490		(7,987		)	4,874
Noncontrolling interests	—		—		495		—			495
Total equity	4,874		4,497		3,985		(7,987		)	5,369
Total liabilities and equity	$	15,178	$	11,460	$	4,918	$	(19,480	)	$	12,076

Condensed Consolidating Financial Information as of December 31, 2016



	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	147	$	53	$	259	$	—		$	459
Accounts receivable, net	2,118		3,330		324		(4,833		)	939
Inventories	—		598		203		—			801
Prepaid expenses and other current assets	31		42		12		(37		)	48
Restricted cash	—		—		161		—			161
Total current assets	2,296		4,023		959		(4,870		)	2,408
Property, plant and equipment, net	—		4,476		1,944		—			6,420
Goodwill	—		792		155		—			947
Customer relationships, net	—		468		143		—			611
Other intangible assets, net	—		131		70		(25		)	176
Other assets, net	9,170		874		1,116		(10,832		)	328
Total assets	$	11,466	$	10,764	$	4,387	$	(15,727	)	$	10,890
Current liabilities
Accounts payable	$	4,331	$	748	$	225	$	(4,808	)	$	496
Accrued liabilities	26		390		183		(61		)	538
Term loan	—		—		149		—			149
Total current liabilities	4,357		1,138		557		(4,869		)	1,183
Long-term debt, net	3,585		4,091		—		(3,997		)	3,679
Deferred income taxes	—		1,581		92		(23		)	1,650
Pension and other liabilities	—		361		125		—			486
Total liabilities	7,942		7,171		774		(8,889		)	6,998
Total Westlake Chemical Corporation stockholders' equity	3,524		3,593		3,245		(6,838		)	3,524
Noncontrolling interests	—		—		368		—			368
Total equity	3,524		3,593		3,613		(6,838		)	3,892
Total liabilities and equity	$	11,466	$	10,764	$	4,387	$	(15,727	)	$	10,890

Condensed Consolidating Financial Information for the Year Ended December 31, 2017



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	6,650		$	3,143		$	(1,752	)	$	8,041
Cost of sales	—			5,559			2,438			(1,725		)	6,272
Gross profit	—			1,091			705			(27		)	1,769
Selling, general and administrative expenses	3			292			131			(27		)	399
Amortization of intangibles	1			81			26			—			108
Transaction and integration-related costs	—			27			2			—			29
Income (loss) from operations	(4		)	691			546			—			1,233
Other income (expense)
Interest expense	(154		)	(178		)	(6		)	179			(159		)
Other income (expense), net	154			(3		)	35			(179		)	7
Income (loss) before income taxes	(4		)	510			575			—			1,081
Provision for (benefit from) income taxes	10			(312		)	44			—			(258		)
Equity in net income of subsidiaries	1,318			—			—			(1,318		)	—
Net income (loss)	1,304			822			531			(1,318		)	1,339
Net income attributable to noncontrolling interests	—			—			35			—			35
Net income (loss) attributable to Westlake Chemical Corporation	$	1,304		$	822		$	496		$	(1,318	)	$	1,304
Comprehensive income attributable to Westlake Chemical Corporation	$	1,432		$	833		$	493		$	(1,326	)	$	1,432

Condensed Consolidating Financial Information for the Year Ended December 31, 2016



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	4,010		$	2,445		$	(1,379	)	$	5,076
Cost of sales	—			3,533			1,919			(1,357		)	4,095
Gross profit	—			477			526			(22		)	981
Selling, general and administrative expenses	2			178			100			(22		)	258
Amortization of intangibles	1			27			10			—			38
Transaction and integration-related costs	—			103			1			—			104
Income (loss) from operations	(3		)	169			415			—			581
Other income (expense)
Interest expense	(83		)	(76		)	(2		)	82			(79		)
Other income (expense), net	77			(14		)	75			(82		)	56
Income (loss) before income taxes	(9		)	79			488			—			558
Provision for (benefit from) income taxes	(8		)	115			31			—			138
Equity in net income of subsidiaries	400			—			—			(400		)	—
Net income (loss)	399			(36		)	457			(400		)	420
Net income attributable to noncontrolling interests	—			—			21			—			21
Net income (loss) attributable to Westlake Chemical Corporation	$	399		$	(36	)	$	436		$	(400	)	$	399
Comprehensive income attributable to Westlake Chemical Corporation	$	407		$	11		$	396		$	(407	)	$	407

Condensed Consolidating Financial Information for the Year Ended December 31, 2015



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	3,558		$	2,286	$	(1,381	)	$	4,463
Cost of sales	—			2,842			1,797		(1,361		)	3,278
Gross profit	—			716			489		(20		)	1,185
Selling, general and administrative expenses	3			146			89		(20		)	218
Amortization of intangibles	—			5			2		—			7
Income (loss) from operations	(3		)	565			398		—			960
Other income (expense)
Interest expense	(42		)	(35		)	—		42			(35		)
Other income (expense), net	20			5			55		(42		)	38
Income (loss) before income taxes	(25		)	535			453		—			963
Provision for (benefit from) income taxes	(7		)	275			30		—			298
Equity in net income of subsidiaries	664			—			—		(664		)	—
Net income (loss)	646			260			423		(664		)	665
Net income attributable to noncontrolling interests	—			—			19		—			19
Net income (loss) attributable to Westlake Chemical Corporation	$	646		$	260		$	404	$	(664	)	$	646
Comprehensive income attributable to Westlake Chemical Corporation	$	596		$	261		$	335	$	(596	)	$	596

Condensed Consolidating Financial Information for the Year Ended December 31, 2017



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	1,304		$	822		$	531		$	(1,318	)	$	1,339
Adjustments to reconcile net income to net cash provided by (used for) operating activities
Depreciation and amortization	—			395			206			—			601
Deferred income taxes	12			(535		)	(11		)	—			(534		)
Net changes in working capital and other	(1,327		)	41			100			1,318			132
Net cash provided by (used for) operating activities	(11		)	723			826			—			1,538
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			(13		)	—			—			(13		)
Additions to property, plant and equipment	—			(407		)	(170		)	—			(577		)
Additions to cost method investment	—			(66		)	—			—			(66		)
Other	—			2			(134		)	136			4
Net cash provided by (used for) investing activities	—			(484		)	(304		)	136			(652		)
Cash flows from financing activities
Intercompany financing	746			(611		)	(135		)	—			—
Receivable under the investment management agreement	136			—			—			(136		)	—
Debt issuance costs	(6		)	—			—			—			(6		)
Dividends paid	(103		)	—			—			—			(103		)
Distributions to noncontrolling interests	—			376			(404		)	—			(28		)
Proceeds from debt issuance and drawdown of revolver	225			—			8			—			233
Net proceeds from issuance of Westlake Chemical Partners LP common units	—			—			111			—			111
Proceeds from senior notes issuance	745			—			—			—			745
Repayment of term loan	—			—			(150		)	—			(150		)
Restricted cash associated with term loan	—			—			154			—			154
Repayment of revolver	(550		)	—			—			—			(550		)
Repayment of notes payable	(251		)	—			(6		)	—			(257		)
Other	11			—			—			—			11
Net cash provided by (used for) financing activities	953			(235		)	(422		)	(136		)	160



	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	—		—		26		—		26
Net increase (decrease) in cash and cash equivalents	942		4		126		—		1,072
Cash and cash equivalents at beginning of the year	147		53		259		—		459
Cash and cash equivalents at end of the year	$	1,089	$	57	$	385	$	—	$	1,531

Condensed Consolidating Financial Information for the Year Ended December 31, 2016



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	399		$	(36	)	$	457		$	(400	)	$	420
Adjustments to reconcile net income to net cash provided by (used for) operating activities
Depreciation and amortization	—			217			161			—			378
Deferred income taxes	1			103			(3		)	—			101
Net changes in working capital and other	(437		)	90			(118		)	400			(65		)
Net cash provided by (used for) operating activities	(37		)	374			497			—			834
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			(2,502		)	64			—			(2,438		)
Additions to property, plant and equipment	—			(275		)	(354		)	—			(629		)
Additions to cost method investments	—			(17		)	—			—			(17		)
Proceeds from sales and maturities of securities	658			—			5			—			663
Purchase of securities	(138		)	—			—			—			(138		)
Other	—			(4		)	—			—			(4		)
Net cash provided by (used for) investing activities	520			(2,798		)	(285		)	—			(2,563		)
Cash flows from financing activities
Intercompany financing	(2,199		)	2,207			(8		)	—			—
Debt issuance costs	(35		)	—			(1		)	—			(36		)
Dividends paid	(97		)	—			—			—			(97		)
Distributions paid	—			263			(280		)	—			(17		)
Proceeds from debt issuance and drawdown of revolver	450			—			158			—			608
Proceeds from senior notes issuance	1,429			—			—			—			1,429
Restricted cash associated with term loan	—			—			(154		)	—			(154		)
Repayment of revolver	(125		)	—			—			—			(125		)
Repayment of notes payable	—			—			(13		)	—			(13		)
Repurchase of common stock for treasury	(67		)	—			—			—			(67		)
Other	5			—			—			—			5
Net cash provided by (used for) financing activities	(639		)	2,470			(298		)	—			1,533



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	—			—		(8		)	—		(8		)
Net increase (decrease) in cash and cash equivalents	(156		)	46		(94		)	—		(204		)
Cash and cash equivalents at beginning of the year	303			7		353			—		663
Cash and cash equivalents at end of the year	$	147		$	53	$	259		$	—	$	459

Condensed Consolidating Financial Information for the Year Ended December 31, 2015



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	646		$	260		$	423		$	(664	)	$	665
Adjustments to reconcile net income to net cash provided by (used for) operating activities
Depreciation and amortization	—			114			132			—			246
Deferred income taxes	—			39			1			—			40
Net changes in working capital and other	(659		)	93			30			664			128
Net cash provided by (used for) operating activities	(13		)	506			586			—			1,079
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			—			16			—			16
Additions to property, plant and equipment	—			(215		)	(276		)	—			(491		)
Proceeds from disposition of equity method investments	—			28			—			—			28
Proceeds from sales and maturities of securities	49			—			—			—			49
Purchase of securities	(556		)	(49		)	—			—			(605		)
Other	—			(3		)	—			—			(3		)
Net cash used for investing activities	(507		)	(239		)	(260		)	—			(1,006		)
Cash flows from financing activities
Intercompany financing	418			(590		)	172			—			—
Dividends paid	(92		)	—			—			—			(92		)
Distributions paid	—			327			(342		)	—			(15		)
Proceeds from debt issuance	—			—			53			—			53
Repayment of notes payable	—			—			(74		)	—			(74		)
Repurchase of common stock for treasury	(163		)	—			—			—			(163		)
Other	4			—			—			—			4
Net cash provided by (used for) financing activities	167			(263		)	(191		)	—			(287		)
Effect of exchange rate changes on cash and cash equivalents	—			—			(4		)	—			(4		)
Net increase (decrease) in cash and cash equivalents	(353		)	4			131			—			(218		)
Cash and cash equivalents at beginning of the year	656			3			222			—			881
Cash and cash equivalents at end of the year	$	303		$	7		$	353		$	—		$	663

- Definition

The entire disclosure for condensed financial information, including the financial position, cash flows, and the results of operations of the registrant (parent company) as of the same dates or for the same periods for which audited consolidated financial statements are being presented. Alternatively, the details of this disclosure can be reported by the specific parent company taxonomy elements, indicating the appropriate date and period contexts in an instance document.

+ References + Details

Quarterly Financial Information

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

Quarterly Financial Information (Unaudited)



	Three Months Ended
	March 31, 2017		June 30, 2017		September 30, 2017		December 31, 2017
Net sales	$	1,943	$	1,979	$	2,109	$	2,010
Gross profit	368		405		498		498
Income from operations	236		266		366		365
Net income	145		159		219		816
Net income attributable to Westlake Chemical Corporation	138		153		211		802
Earnings per common share attributable to Westlake Chemical Corporation: ⁽¹⁾
Basic	$	1.07	$	1.18	$	1.62	$	6.18
Diluted	$	1.06	$	1.17	$	1.61	$	6.15

	Three Months Ended
	March 31, 2016		June 30, 2016		September 30, 2016		December 31, 2016
Net sales	$	975	$	1,086	$	1,280	$	1,735
Gross profit	255		241		203		282
Income from operations	202		180		46		153
Net income	129		116		70		105
Net income attributable to Westlake Chemical Corporation	123		111		66		99
Earnings per common share attributable to Westlake Chemical Corporation: ⁽¹⁾
Basic	$	0.94	$	0.85	$	0.51	$	0.76
Diluted	$	0.94	$	0.85	$	0.51	$	0.76

______________________________


(1)	Basic and diluted earnings per common share ("EPS") for each quarter is computed using the weighted average shares outstanding during that quarter, while EPS for the year is computed using the weighted average shares outstanding for the year. As a result, the sum of the EPS for each of the four quarters may not equal the EPS for the year.

Description Of Business And Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Westlake Chemical Corporation (the "Company") operates as an integrated global manufacturer and marketer of basic chemicals, vinyls, polymers and building products. These products include some of the most widely used chemicals in the world, which are fundamental to many diverse consumer and industrial markets, including flexible and rigid packaging, automotive products, coatings, residential and commercial construction as well as other durable and non-durable goods. The Company's customers range from large chemical processors and plastics fabricators to small construction contractors, municipalities and supply warehouses primarily throughout North America and Europe. The petrochemical industry is subject to price fluctuations and volatile feedstock pricing typical of a commodity-based industry, the effects of which may not be immediately passed along to customers.
Acquisition of Axiall Corporation	Acquisition of Axiall Corporation On August 31, 2016, the Company completed the acquisition of Axiall Corporation ("Axiall") for $33.00 per share in an all-cash transaction (the "Merger"), pursuant to the terms of the Agreement and Plan of Merger (the "Merger Agreement"), dated as of June 10, 2016, by and among Westlake, Axiall and Lagoon Merger Sub, Inc., a wholly-owned subsidiary of Westlake (the "Merger Sub"). During the third quarter of 2016, in order to finance a portion of the consideration and related fees and expenses, and for other general corporate purposes, the Company issued $1,450 aggregate principal amount of senior notes. In addition, the Company entered into a $1,000 unsecured revolving credit facility (the "Credit Agreement").
Westlake Chemical Partners LP	Westlake Chemical Partners LP In 2014, the Company formed Westlake Chemical Partners LP ("Westlake Partners") to operate, acquire and develop ethylene production facilities and related assets. Westlake Partners' assets consist of a limited partner interest in Westlake Chemical OpCo LP ("OpCo"), as well as the general partner interest in OpCo. OpCo's assets include two ethylene production facilities at the Company's Lake Charles, Louisiana site, one ethylene production facility at the Company's Calvert City, Kentucky site and a 200-mile common carrier ethylene pipeline that runs from Mont Belvieu, Texas to the Company's Longview, Texas site. As of December 31, 2017, the Company held an 81.7% limited partner interest in OpCo and a controlling interest in Westlake Partners. The operations of Westlake Partners are consolidated in the Company's financial statements.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and subsidiaries in which the Company directly or indirectly owns more than a 50% voting interest and exercises control and, when applicable, entities for which the Company has a controlling financial interest or is the primary beneficiary. Investments in majority-owned companies where the Company does not exercise control and investments in nonconsolidated affiliates (20%-50% owned companies, joint ventures and partnerships) are accounted for using the equity method of accounting. Undistributed earnings from joint ventures included in retained earnings were immaterial as of December 31, 2017. All intercompany transactions and balances are eliminated in consolidation. Noncontrolling interests represent the direct equity interests held by investors in the Company's consolidated subsidiaries, Westlake Partners and Taiwan Chlorine Industries, Ltd.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments which potentially subject the Company to concentration of risk consist principally of trade receivables from customers engaged in manufacturing polyethylene products, polyvinyl chloride ("PVC") products and PVC pipe products. The Company performs periodic credit evaluations of the customers' financial condition and generally does not require collateral. The Company maintains allowances for potential losses.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The determination of the allowance for doubtful accounts is based on estimation of the amount of accounts receivable that the Company believes are unlikely to be collected. Estimating this amount requires analysis of the financial strength of the Company's customers, the use of historical experience, the Company's accounts receivable aged trial balance, and specific collectibility analysis. The allowance for doubtful accounts is reviewed quarterly. Past due balances over 90 days and high risk accounts as determined by the analysis of financial strength of customers are reviewed individually for collectibility.
Inventories	Inventories Inventories primarily include product, material and supplies. Inventories are stated at lower of cost or net realizable value. Cost is determined using the first-in, first-out ("FIFO") or average method.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects. Capitalized interest was $4, $10 and $10 for the years ended December 31, 2017, 2016 and 2015, respectively. Repair and maintenance costs are charged to operations as incurred. Gains and losses on the disposition or retirement of fixed assets are reflected in the consolidated statement of operations when the assets are sold or retired. The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract.
Impairment of Long-Lived Assets and Impairment of Goodwill and Intangible Assets	Impairment of Long-Lived Assets The accounting guidance for the impairment or disposal of long-lived assets requires that the Company review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Long-lived assets assessed for impairment are grouped at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future net undiscounted cash flows expected to be generated by the asset. Assets are considered to be impaired if the carrying amount of an asset exceeds the future undiscounted cash flows. The impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or estimated fair value less costs to sell. Impairment of Goodwill and Intangible Assets The accounting guidance requires that goodwill is tested for impairment at least annually, or when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below its carrying value. The Company performed its annual impairment tests for the Olefins and Vinyls segments' goodwill in October 2017 and April 2017, respectively, and the impairment tests indicated that the recorded goodwill was not impaired. There has been no impairment of the Olefins or Vinyls segments' goodwill since the goodwill was initially recorded. Other intangible assets with finite lives are amortized over their estimated useful lives and reviewed for impairment in accordance with the provisions of the accounting guidance. See Note 7 for more information on the Company's annual goodwill impairment tests.
Property, Plant and Equipment, Planned Major Maintenance Activities, Policy [Policy Text Block]	Turnaround Costs The Company accounts for turnaround costs under the deferral method. Turnarounds are the scheduled and required shutdowns of specific operating units in order to perform planned major maintenance activities. The costs related to the significant overhaul and refurbishment activities include maintenance materials, parts and direct labor costs. The costs of the turnaround are deferred when incurred at the time of the turnaround and amortized (within depreciation and amortization) on a straight-line basis until the next planned turnaround, which ranges from three to six years. Deferred turnaround costs are presented as a component of other assets, net. The cash outflows related to these costs are included in operating activities in the consolidated statement of cash flows.
Business Combinations	Business Combinations The Company records business combinations using the acquisition method of accounting. Under the acquisition method of accounting, identifiable assets acquired and liabilities assumed are recorded at their acquisition date fair values. The excess of the purchase price over the estimated fair value is recorded as goodwill. Changes in the estimated fair values of net assets recorded for acquisitions prior to the finalization of more detailed analysis, but not to exceed one year from the date of acquisition, will adjust the amount of the purchase price allocable to goodwill. Measurement period adjustments are reflected in the period in which they occur.
Income Taxes	Income Taxes The Company utilizes the liability method of accounting for deferred income taxes. Under the liability method, deferred tax assets or liabilities are recorded based upon temporary differences between the tax basis of assets and liabilities and their carrying values for financial reporting purposes. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities during the period. Valuation allowances are recorded against deferred tax assets when it is considered more likely than not that the deferred tax assets will not be realized. On December 22, 2017, the United States ("U.S.") Tax Cuts and Jobs Act (the "Tax Act") was signed into law. The Tax Act, among other changes, reduces the U.S. corporate income tax rate from 35% to 21%, effective January 1, 2018, and also requires a one-time deemed repatriation of foreign earnings at specified rates. The Company made a provisional adjustment of $591 of income tax benefit in the 2017 consolidated financial statements for items that the Company could reasonably estimate such as revaluation of deferred tax assets and liabilities and a one-time U.S. tax on the mandatory deemed repatriation of the Company's post-1986 foreign earnings. For additional information, see Note 15.
Foreign Currency Translation	Foreign Currency Translation Assets and liabilities of foreign subsidiaries are translated to U.S. dollars at the exchange rate as of the end of the year. Statement of operations items are translated at the average exchange rate for the year. The resulting translation adjustment is recorded as a separate component of stockholders' equity.
Revenue Recognition	Revenue Recognition Revenue is recognized when persuasive evidence of an arrangement exists, products are delivered to the customer, the sales price is fixed or determinable and collectability is reasonably assured. For domestic contracts, title and risk of loss passes to the customer upon delivery under executed customer purchase orders or contracts. For export contracts, the title and risk of loss passes to customers at the time specified by each contract. Provisions for discounts, rebates and returns are provided for in the same period as the related sales are recorded.
Transportation and Freight	Transportation and Freight Amounts billed to customers for freight and handling costs on outbound shipments are included in net sales in the consolidated statements of operations. Transportation and freight costs incurred by the Company on outbound shipments are included in cost of sales in the consolidated statements of operations.
Price Risk Management	Price Risk Management The accounting guidance for derivative instruments and hedging activities requires that the Company recognize all derivative instruments on the balance sheet at fair value, and changes in the derivative's fair value must be currently recognized in earnings or comprehensive income, depending on the designation of the derivative. If the derivative is designated as a fair value hedge, the changes in the fair value of the derivative and of the hedged item attributable to the hedged risk are recognized in earnings. If the derivative is designated as a cash flow hedge, the effective portion of the change in the fair value of the derivative is recorded in comprehensive income and is recognized in the statement of operations when the hedged item affects earnings. Ineffective portions of changes in the fair value of cash flow hedges are recognized in earnings currently.
Asset Retirement Obligations	Asset Retirement Obligations The Company has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Company's manufacturing facilities. The Company recognizes asset retirement obligations in the period in which the liability becomes probable and reasonably estimable. Recognized asset retirement obligations are initially recorded at fair value and capitalized as a component of the carrying value of the long-lived asset to which the obligation relates. The liability is accreted to its future value each period, and the capitalized cost is depreciated over the estimated useful life of the related asset. Upon settlement of the liability, a gain or loss is recorded. As of December 31, 2017, the Company had $3 and $18 of asset retirement obligations recorded as accrued liabilities and other liabilities, respectively. As of December 31, 2016, the Company had $4 and $17 of asset retirement obligations recorded as accrued liabilities and other liabilities, respectively. The Company also has conditional asset retirement obligations that have not been recognized because the fair values of the conditional legal obligations cannot be measured due to the indeterminate settlement date of the obligations. Settlements of the unrecognized conditional asset retirement obligations are not expected to have a material adverse effects on the Company's financial condition, results of operations or cash flows in any individual reporting period.
Environmental Costs	Environmental Costs Environmental costs relating to current operations are expensed or capitalized, as appropriate, depending on whether such costs provide future economic benefits. Remediation liabilities are recognized when the costs are considered probable and can be reasonably estimated. Measurement of liabilities is based on currently enacted laws and regulations, existing technology and undiscounted site-specific costs. Environmental liabilities in connection with properties that are sold or closed are realized upon such sale or closure, to the extent they are probable and estimable and not previously reserved. Recognition of any joint and several liabilities is based upon the Company's best estimate of its final pro rata share of the liability.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
New Accounting Pronouncements	Recent Accounting Pronouncements Revenue from Contracts with Customers (ASU No. 2014-09) In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that will supersede the existing revenue recognition guidance. The new accounting guidance creates a framework by which an entity will allocate the transaction price to separate performance obligations and recognize revenue when each performance obligation is satisfied. Under the new standard, entities will be required to use judgment and make estimates, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price, allocating the transaction price to each separate performance obligation and determining when an entity satisfies its performance obligations. The standard allows for either "full retrospective" adoption, meaning that the standard is applied to all of the periods presented with a cumulative catch-up as of the earliest period presented, or "modified retrospective" adoption, meaning the standard is applied only to the most current period presented in the financial statements with a cumulative catch-up as of the current period. In July and December 2016, the FASB issued various additional authoritative guidance for the new revenue recognition standard. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. The Company has elected the modified retrospective method of adoption. Recognition and Measurement of Financial Assets and Financial Liabilities (ASU No. 2016-01) In January 2016, the FASB issued an accounting standards update making certain changes principally to the current guidance for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. Among other things, the guidance (1) requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value, with changes in fair value recognized in net income; (2) provide entities with a policy election to record equity investments without readily determinable fair values at cost, less impairment, and subsequent adjustments for observable price changes (changes in the basis of these equity investments to be reported in net income); (3) requires an entity that has elected the fair value option for financial liabilities to recognize changes in fair value due to instrument-specific credit risk separately in other comprehensive income; (4) clarified current guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities; and (5) requires specific disclosure pertaining to financial assets and financial liabilities in the financial statements. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Leases (ASU No. 2016-02) In February 2016, the FASB issued an accounting standards update on a new lease standard that will supersede the existing lease guidance. The standard requires a lessee to recognize assets and liabilities related to long-term leases that are classified as operating leases under current guidance on its balance sheet. An asset would be recognized related to the right to use the underlying asset and a liability would be recognized related to the obligation to make lease payments over the term of the lease. The standard also requires expanded disclosures related to leases. The accounting standard will be effective for reporting periods beginning after December 15, 2018. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows. Credit Losses (ASU No. 2016-13) In June 2016, the FASB issued an accounting standards update providing new guidance for the accounting for credit losses on loans and other financial instruments. The new guidance introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. The standard also modifies the impairment model for available-for-sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. The accounting standard will be effective for reporting periods beginning after December 15, 2019 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Cash Flows (ASU No. 2016-15) In August 2016, the FASB issued an accounting standards update providing new guidance on the classification of certain cash receipts and payments including debt extinguishment costs, debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments, proceeds from the settlement of insurance claims and life insurance policies and distributions received from equity method investees in the statement of cash flows. This update is required to be applied using the retrospective transition method to each period presented unless it is impracticable to be applied retrospectively. In such situation, this guidance is to be applied prospectively. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Cash Flows (ASU No. 2016-18) In November 2016, the FASB issued an accounting standards update to clarify certain existing principles in Accounting Standards Codification ("ASC") 230, Cash flows, including providing additional guidance related to transfers between cash and restricted cash and how entities present, in their statement of cash flows, the cash receipts and cash payments that directly affect the restricted cash accounts. The accounting standard will be effective for reporting periods beginning after December 15, 2017. Upon adoption, the Company will retrospectively adjust its financial statements to reflect restricted cash in the beginning and ending cash and restricted cash balances within the statements of cash flows. Transfers between cash and restricted cash will be excluded from net changes in cash and cash equivalents within the statements of cash flows. Business Combinations (ASU No. 2017-01) In January 2017, the FASB issued an accounting standards update to assist entities with evaluating when a set of transferred assets and activities is a business. The guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs by more closely aligning it with how outputs are described in ASC 606. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Intangibles-Goodwill and Other (ASU No. 2017-04) In January 2017, the FASB issued an accounting standards update to simplify the subsequent measurement of goodwill. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The accounting standard will be effective for reporting periods beginning after December 15, 2019 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (ASU No. 2017-05) In February 2017, the FASB issued an accounting standards update to clarify the scope of guidance related to other income—gains and losses from the derecognition of nonfinancial assets, and to add guidance for partial sales of nonfinancial assets. The new guidance clarifies that an in substance nonfinancial asset is an asset or group of assets for which substantially all of the fair value consists of nonfinancial assets and the group or subsidiary is not a business. The guidance also outlines that when an entity transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling interest, it will measure the retained interest at fair value resulting in full gain or loss recognition upon sale of the controlling interest. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Compensation - Retirement Benefits (ASU No. 2017-07) In March 2017, the FASB issued an accounting standards update to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. The new guidance requires employers to disaggregate the service cost component from the other components of net periodic benefit cost and report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The amendments also allow only the service cost component to be eligible for capitalization when applicable. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Compensation - Stock Compensation (ASU No. 2017-09) In May 2017, the FASB issued the accounting standards update to provide clarity and reduce both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in this update provide guidance about which changes to the terms or conditions of a share-based payment award require the application of modification accounting in Topic 718. Essentially, an entity will not have to account for the effects of a modification if: (1) the fair value of the modified award is the same immediately before and after the modification; (2) the vesting conditions of the modified award are the same immediately before and after the modification; and (3) the classification of the modified award as either an equity instrument or liability instrument is the same immediately before and after the modification. This update is to be applied prospectively to an award modified on or after the adoption date. Early adoption is permitted. The accounting standard will be effective for reporting periods beginning after December 15, 2017 and is not expected to have a material impact on the Company's consolidated financial position, results of operations and cash flows. Derivatives and Hedging - Targeted Improvements to Accounting for Hedging Activities (ASU No. 2017-12) In August 2017, the FASB issued an accounting standards update to improve financial reporting of hedging relationships, to better portray the economic results of an entity's risk management activities in the financial statements and to simplify application of hedge accounting guidance. The accounting standard eliminates certain hedge effectiveness measurement and reporting requirements and expands the types of permissible hedging strategies. The accounting standard will be effective for reporting periods beginning after December 15, 2018, and interim periods within those fiscal years. Early application is permitted in any interim period after issuance, to be applied retrospectively to the beginning of the fiscal year. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows. Recently Adopted Accounting Standards Investments-Equity Method and Joint Ventures (ASU No. 2016-07) In March 2016, the FASB issued an accounting standards update providing new guidance for the accounting for equity method investments. The new guidance eliminates the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. In addition, the guidance requires that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. Therefore, upon qualifying for the equity method of accounting, no retroactive adjustment of the investment is required. The accounting standard is effective for reporting periods beginning after December 15, 2016. The Company adopted this accounting standard effective January 1, 2017 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Stock Compensation (ASU No. 2016-09) In March 2016, the FASB issued an accounting standards update to simplify several aspects of the accounting for share-based payment transactions, including income tax consequences, classifications of awards as either equity or liabilities and certain related classifications on the statement of cash flows. In addition, the new guidance permits entities to make an accounting policy election for the impact of forfeitures on the recognition of expense for share-based payment awards. Forfeitures can be estimated, as required today, or recognized when they occur. The accounting standard is effective for reporting periods beginning after December 15, 2016. The Company adopted this accounting standard effective January 1, 2017 and elected to continue estimating forfeitures as required prior to adoption of the accounting standards update. The adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Amendments to the Consolidation Analysis (ASU No. 2016-17) In October 2016, the FASB issued an accounting standards update making certain changes to the current consolidation guidance. The amendments affect reporting entities that are required to evaluate whether they should consolidate a variable interest entity in certain situations involving entities under common control. Specifically, the amendments change the evaluation of whether a reporting entity is the primary beneficiary of a variable interest entity by changing how a reporting entity that is a single decision maker of a variable interest entity treats indirect interests in the entity held through related parties that are under common control with the reporting entity. The amendments will be effective for annual periods beginning after December 15, 2016. The Company adopted this accounting standard, applied prospectively, effective January 1, 2017, and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Description Of Business And Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Estimated Useful Lives of Assets

Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows:



Classification		Years
Buildings and improvements		40
Plant and equipment		25
Ethylene pipeline		35
Other		3-15

Acquisitions (Tables)

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Schedule of Business Acquisitions



	Final Purchase Consideration as of August 31, 2016
Closing stock purchase:
Offer per share	$	33.00
Multiplied by number of shares outstanding at acquisition (in thousands of shares)	67,277
Fair value of Axiall shares outstanding purchased by the Company	2,220
Plus:
Axiall debt repaid at acquisition	247
Seller's transaction costs paid by the Company ⁽¹⁾	48
Total fair value of consideration transferred	2,515

Fair value of Axiall share-based awards attributed to pre-combination service ⁽²⁾	12
Additional settlement value of shares acquired	13
Purchase consideration	2,540

Fair value of previously held equity interest in Axiall ⁽³⁾	102
Total fair value allocated to net assets acquired	$	2,642

______________________________


(1)	Transactions costs incurred by the seller included legal and advisory costs incurred for the benefit of Axiall's former shareholders and board of directors to evaluate the Company's initial Merger proposals, explore strategic alternatives and negotiate the purchase price.


(2)	The fair value of share-based awards attributable to pre-combination service includes the ratio of the pre-combination service performed to the original service period of the Axiall restricted share units and options, including related dividend equivalent rights.


(3)	Prior to the Merger, the Company owned 3.1 million shares in Axiall. The investment in Axiall was carried at estimated fair value with unrealized gains recorded as a component of accumulated other comprehensive loss in the consolidated balance sheet. The Company recognized a $49 gain for the investment in other income, net in the consolidated statements of operations upon gaining control.

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

The following table summarizes the purchase price allocation:



	Net Assets Acquired as of August 31, 2016
Cash	$	88
Accounts receivable ⁽¹⁾	422
Income tax receivable	51
Inventories ⁽²⁾	349
Prepaid expenses and other current assets	56
Property, plant and equipment ⁽²⁾	2,942
Customer relationships (weighted average lives of 9.8 years) ⁽³⁾	670
Other intangible assets:
Trade name (weighted average lives of 6.8 years)	50
Technology (weighted average lives of 5.4 years)	42
Supply contracts and leases (weighted average lives of 6.3 years)	27
Other assets	94
Total assets acquired	$	4,791
Accounts and notes payable	254
Interest payable	8
Income tax payable	2
Accrued compensation	44
Accrued liabilities	154
Deferred income taxes ⁽⁴⁾	958
Tax reserve non-current	3
Pension and other post-retirement obligations	311
Other liabilities	102
Long-term debt	1,187
Total liabilities assumed	$	3,023
Total identifiable net assets acquired	$	1,768
Noncontrolling interest	(68		)
Goodwill	942
Total fair value allocated to net assets acquired	$	2,642

______________________________


(1)	The fair value of accounts receivable acquired was $422, with the gross contractual amount being $435. The Company expects $13 to be uncollectible.


(2)	The Company obtained additional information related to its inventories and property, plant and equipment, which led to an increase in inventories of $43, a decrease in property plant and equipment of $193 and a corresponding increase in goodwill of $150 compared to the estimated fair values included in the 2016 Form 10-K.


(3)	The Company obtained additional information related to its customer relationship balances which led to an increase in customer relationships of $80 and a corresponding decrease in goodwill compared to the estimated fair values included in the 2016 Form 10-K.


(4)	Decreases in the estimated fair values of identified assets acquired led to a decrease in deferred income taxes of $27 compared to the estimated fair values included in the 2016 Form 10-K.

Pro Forma Information

The following unaudited consolidated pro forma information presents consolidated pro forma information as if the Merger had occurred on January 1, 2015:



	Pro Forma
	Year Ended December 31,
	2016		2015
Net sales	$	7,081	$	7,793

Net income ⁽¹⁾	$	397	$	663
Net income (loss) attributable to noncontrolling interest	23		(2		)
Net income attributable to Westlake Chemical Corporation ⁽¹⁾	$	374	$	665
Earnings per common share attributable to Westlake Chemical Corporation:
Basic	$	2.88	$	5.02
Diluted	$	2.86	$	5.00

______________________________

(1)

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of Realized Gain (Loss)



	Year Ended December 31,
	2017		2016		2015
Proceeds from sales and maturities of securities	$	—	$	663	$	49
Gross realized gains	—		54		4

Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Schedule Of Accounts Receivable

Accounts receivable consist of the following at December 31:



	2017			2016
Trade customers	$	974		$	820
Affiliates	9			8
Allowance for doubtful accounts	(22		)	(18		)
	961			810
Federal and state taxes	7			90
Other	33			39
Accounts receivable, net	$	1,001		$	939

Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Inventory, Net [Abstract]

Schedule Of Inventory

Inventories consist of the following at December 31:



	2017		2016
Finished products	$	549	$	501
Feedstock, additives and chemicals	221		217
Materials and supplies	130		83
Inventories	$	900	$	801

Property, Plant And Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment, Net [Abstract]

Schedule Of Property, Plant And Equipment

Property, plant and equipment consist of the following at December 31:



	2017			2016
Land	$	198		$	194
Buildings and improvements	495			465
Plant and equipment	7,281			6,914
Other	388			377
	8,362			7,950
Less: Accumulated depreciation	(2,338		)	(1,919		)
	6,024			6,031
Construction in progress	388			389
Property, plant and equipment, net	$	6,412		$	6,420

Goodwill, Intangibles and Other Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The gross carrying amounts of goodwill for the years ended December 31, 2017 and 2016 are as follows:



	Olefins Segment		Vinyls Segment			Total
Balance at December 31, 2015	$	30	$	32		$	62
Goodwill acquired during the year	—		888			888
Effects of changes in foreign exchange rates	—		(3		)	(3		)
Balance at December 31, 2016	30		917			947
Measurement period adjustment	—		55			55
Effects of changes in foreign exchange rates	—		10			10
Balance at December 31, 2017	$	30	$	982		$	1,012

Finite-Lived Intangible Assets

Intangible assets consisted of the following at December 31:



	2017							2016							Weighted Average Life
	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net		Weighted Average Life
Customer relationships	$	754	$	(138	)	$	616	$	662	$	(51	)	$	611	10
Other intangible assets:
Licenses and intellectual property	124		(55		)	69		121		(44		)	77		13
Trademarks	93		(17		)	76		88		(7		)	81		13
Other	31		(15		)	16		31		(13		)	18		12
Total other intangible assets	$	248	$	(87	)	$	161	$	240	$	(64	)	$	176

Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule Of Long-Term Debt

Long-term debt consisted of the following at December 31:



	December 31, 2017							December 31, 2016
	Principal Amount		Unamortized Premium, Discount and Debt Issuance Costs			Net Long-Term Debt		Principal Amount		Unamortized Premium, Discount and Debt Issuance Costs			Net Long-Term Debt
Revolving credit facility	$	—	$	—		$	—	$	325	$	—		$	325
4.625% senior notes due 2021 (the "4.625% Westlake 2021 Senior Notes")	625		20			645		625		27			652
4.625% senior notes due 2021 (the "4.625% Subsidiary 2021 Senior Notes")	63		2			65		63		3			66
3.60% senior notes due 2022 (the "3.60% 2022 Senior Notes")	250		(1		)	249		250		(2		)	248
4.875% senior notes due 2023 (the "4.875% Westlake 2023 Senior Notes")	434		11			445		434		13			447
4.875% senior notes due 2023 (the "4.875% Subsidiary 2023 Senior Notes")	16		—			16		16		1			17
3.60% senior notes due 2026 (the "3.60% 2026 Senior Notes")	750		(10		)	740		750		(11		)	739
Loan related to tax-exempt waste disposal revenue bonds due 2027	11		—			11		11		—			11
6 ½% senior notes due 2029 (the "6 ½% 2029 GO Zone Senior Notes")	100		(1		)	99		100		(1		)	99
6 ¾% senior notes due 2032 (the "6 ¾% 2032 GO Zone Senior Notes")	—		—			—		250		(2		)	248
6 ½% senior notes due 2035 (the "6 ½% 2035 GO Zone Senior Notes")	89		(1		)	88		89		(1		)	88
6 ½% senior notes due 2035 (the "6 ½% 2035 IKE Zone Senior Notes")	65		—			65		65		—			65
5.0% senior notes due 2046 (the "5.0% 2046 Senior Notes")	700		(25		)	675		700		(26		)	674
4.375% senior notes due 2047 (the "4.375% 2047 Senior Notes")	500		(9		)	491		—		—			—
3.50% senior notes due 2032 (the "3.50% 2032 Go Zone Refunding Senior Notes")	250		(2		)	248		—		—			—
Total long-term debt	3,853		(16		)	3,837		3,678		1			3,679
Less: Current portion - 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes	688		22			710		—		—			—
Long-Term Debt, net of current portion	$	3,165	$	(38	)	$	3,127	$	3,678	$	1		$	3,679

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive income (loss) by component were as follows:



	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2015	$	(8	)	$	(116	)	$	(5	)	$	(129	)
Other comprehensive income (loss) before reclassifications	36			(34		)	57			59
Amounts reclassified from accumulated other comprehensive income (loss)	1			—			(52		)	(51		)
Net other comprehensive income (loss) attributable to Westlake Chemical Corporation	37			(34		)	5			8
Balances at December 31, 2016	29			(150		)	—			(121		)
Other comprehensive income before reclassifications	12			114			—			126
Amounts reclassified from accumulated other comprehensive income (loss)	2			—			—			2
Net other comprehensive income attributable to Westlake Chemical Corporation	14			114			—			128
Balances at December 31, 2017	$	43		$	(36	)	$	—		$	7

Reclassification out of Accumulated Other Comprehensive Income

The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations:



Details about Accumulated Other Comprehensive Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Year Ended December 31,
		2017			2016			2015
Amortization of pension and other post-retirement items
Net loss	(1)	$	(2	)	$	(2	)	$	(3	)
		(2		)	(2		)	(3		)
	Benefit from income taxes	—			1			1
		(2		)	(1		)	(2		)
Net unrealized gains on available-for- sale investments
Realized gain on available- for-sale investments	Other income, net	—			54			4
	Provision for income taxes	—			(2		)	(1		)
		—			52			3
Total reclassifications for the period		$	(2	)	$	51		$	1

______________________________


(1)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, see Note 12.

Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2017

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule Of Accumulated Benefit Obligations In Excess Of Plan Assets

Pension plans with an accumulated benefit obligation in excess of plan assets at December 31 are as follows:



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Information for pension plans with an accumulated benefit obligation in excess of plan assets
Projected benefit obligation	$	(807	)	$	(128	)	$	(799	)	$	(113	)
Accumulated benefit obligation	(807		)	(126		)	(799		)	(110		)
Fair value of plan assets	650			5			614			5

Schedule Of Net Benefit Costs And Amounts Recognized In Other Comprehensive Income

The following table provides the components of net periodic benefit costs, other changes in plan assets and benefit obligation recognized in other comprehensive income.



	Year Ended December 31,
	2017						2016					2015
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Components of net periodic benefit cost
Service cost	$	3		$	2		$	1		$	2	$	—		$	2
Administrative expenses	2			—			3			—		—			—
Interest cost	25			2			9			2		2			2
Expected return on plan assets	(40		)	(1		)	(15		)	—		(3		)	—
Net amortization	1			1			1			—		1			1
Settlement benefits	—			—			—			—		1			—
Net periodic benefit cost (gain)	$	(9	)	$	4		$	(1	)	$	4	$	1		$	5

Other changes in plan assets and benefit obligation recognized in other comprehensive income (OCI)
Net loss (gain) emerging	$	(18	)	$	—		$	(67	)	$	13	$	1		$	(17	)
Amortization of net loss	(1		)	(1		)	(1		)	—		(2		)	(1		)
Total recognized in OCI	$	(19	)	$	(1	)	$	(68	)	$	13	$	(1	)	$	(18	)
Total net periodic benefit cost and OCI	$	(28	)	$	3		$	(69	)	$	17	$	—		$	(13	)

Schedule Of Weighted Average Assumptions Used

The weighted-average assumptions used to determine pension plan obligations and net periodic benefit costs for the plans are as follows:



	2017				2016				2015
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans
Weighted average assumptions used to determine benefit obligations at December 31
Discount rate	3.4	%	1.8	%	3.8	%	1.8	%	4.0	%	2.4	%
Rate of compensation increase	—	%	2.6	%	—	%	2.6	%	—	%	2.5	%
Weighted average assumptions used to determine net periodic benefit costs for years ended December 31
Discount rate for benefit obligations	3.8	%	1.8	%	3.2	%	2.4	%	3.5	%	1.9	%
Discount rate for service cost	4.1	%	1.9	%	3.4	%	2.4	%	—	%	—	%
Discount rate for interest cost	3.2	%	2.0	%	2.9	%	2.4	%	—	%	—	%
Expected return on plan assets	6.8	%	3.8	%	6.8	%	4.6	%	7.0	%	—	%
Rate of compensation increase	N/A		2.6	%	—	%	2.6	%	—	%	2.5	%

Schedule Of Fair Value Of Pension Plan Assets



	2017
	U.S. Plans						Non U.S. Plans
	Level 1		Level 2		Total		Level 1		Level 2		Total
Cash and common stock:
Cash and cash equivalents	$	—	$	—	$	—	$	5	$	—	$	5
Common stock	21		—		21		—		—		—
Collective investment trust and mutual funds—Equity securities:
Large-cap funds ⁽¹⁾	49		173		222		—		2		2
Small-cap funds ⁽²⁾	9		25		34		—		—		—
International funds ⁽³⁾	69		50		119		—		5		5
Collective investment trust and mutual funds—Fixed income:
Bond funds ⁽⁴⁾	116		125		241		—		6		6
Short-term investment funds	—		13		13		—		—		—
	$	264	$	386	$	650	$	5	$	13	$	18



	2016
	U.S. Plans						Non U.S. Plans
	Level 1		Level 2		Total		Level 1		Level 2		Total
Cash and common stock:
Cash and cash equivalents	$	—	$	—	$	—	$	5	$	—	$	5
Common stock	17		—		17		—		—		—
Collective investment trust and mutual funds—Equity securities:
Large-cap funds ⁽¹⁾	50		167		217		—		2		2
Small-cap funds ⁽²⁾	8		23		31		—		—		—
International funds ⁽³⁾	53		54		107		—		4		4
Collective investment trust and mutual funds—Fixed income:
Bond funds ⁽⁴⁾	62		165		227		—		5		5
Short-term investment funds	—		15		15		—		—		—
	$	190	$	424	$	614	$	5	$	11	$	16

______________________________


(1)	Substantially all of the assets of these funds are invested in large-cap U.S. companies. The remainder of the assets of these funds is invested in cash reserves.


(2)	Substantially all of the assets of these funds are invested in small-cap U.S. companies. The remainder of the assets of these funds is invested in cash reserves.


(3)	Substantially all of the assets of these funds are invested in international companies in developed markets (excluding the U.S.). The remainder of the assets of these funds is invested in cash reserves.


(4)	This category represents investment grade bonds of U.S. issuers, including U.S. Treasury notes.

Schedule of Multi-employer Plans

Contributions to the Company's multi-employer plans are expensed as incurred and were as follows:



	Year Ended December 31,
	2017		2016		2015
	Non-U.S. Plans		Non-U.S. Plans		Non-U.S. Plans
Contributions to multi-employer plans ⁽¹⁾	$	8	$	5	$	4

______________________________

(1)

Schedule Of Estimated Future Benefit Payments

The following benefit payments are expected to be paid:



	Pension Benefits		Other Post- retirement Benefits
Estimated future benefit payments:
Year 1	$	51	$	8
Year 2	53		8
Year 3	52		8
Year 4	52		8
Year 5	53		8
Years 6 to 10	265		30

Defined Benefit Plans [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan

Details of the changes in benefit obligations, plan assets and funded status of the Company's pension plans are as follows:



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Change in benefit obligation
Benefit obligation, beginning of year	$	799		$	125		$	62		$	95
Benefit obligation assumed with acquisition	—			—			818			21
Service cost	3			2			1			1
Interest cost	25			3			9			2
Actuarial loss (gain)	41			—			(74		)	13
Benefits paid	(45		)	(3		)	(17		)	(3		)
Settlements	(16		)	(1		)	—			—
Foreign exchange effects	—			16			—			(4		)
Benefit obligation, end of year	$	807		$	142		$	799		$	125

Change in plan assets
Fair value of plan assets, beginning of year	$	614		$	16		$	51		$	—
Acquisition	—			—			576			16
Actual return	97			1			7			—
Employer contribution	2			1			—			3
Benefits paid	(45		)	—			(17		)	(3		)
Administrative expenses paid	(2		)	—			(3		)	—
Settlements	(16		)	(1		)	—			—
Foreign exchange effects	—			1			—			—
Fair value of plan assets, end of year	$	650		$	18		$	614		$	16
Funded status, end of year	$	(157	)	$	(124	)	$	(185	)	$	(109	)

Schedule of Amounts Recognized in Balance Sheet



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Amounts recognized in the consolidated balance sheet at December 31
Current liabilities	$	(2	)	$	(3	)	$	(2	)	$	(2	)
Noncurrent liabilities	(155		)	(121		)	(183		)	(107		)
Net amount recognized	$	(157	)	$	(124	)	$	(185	)	$	(109	)

Schedule of Amounts Recognized in Other Comprehensive Income (Loss)



	2017					2016
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Amounts recognized in accumulated other comprehensive income (loss)
Net loss (gain)	$	(71	)	$	9	$	(53	)	$	8
Total before tax ⁽¹⁾	$	(71	)	$	9	$	(53	)	$	8

______________________________


(1)	After-tax totals for pension benefits were $43 and $30 for 2017 and 2016, respectively, and are reflected in stockholders' equity as accumulated other comprehensive income.

Other Postretirement Plan Benefits [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan

The following table provides a reconciliation of the benefit obligations of the Company's unfunded post-retirement healthcare plans.



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Change in benefit obligation
Benefit obligation, beginning of year	$	80		$	3		$	18		$	—
Benefit obligation assumed with acquisition	—			—			69			3
Service cost	1			—			—			—
Interest cost	2			—			1			—
Actuarial loss (gain)	(1		)	—			(6		)	—
Benefits paid	(9		)	—			(2		)	—
Benefit obligation, end of year	$	73		$	3		$	80		$	3

Change in plan assets
Fair value of plan assets, beginning of year	$	—		$	—		$	—		$	—
Employer contribution	9			—			2			—
Plan participants' contributions	—			—			—			—
Benefits paid	(9		)	—			(2		)	—
Fair value of plan assets, end of year	$	—		$	—		$	—		$	—
Funded status, end of year	$	(73	)	$	(3	)	$	(80	)	$	(3	)

Schedule of Amounts Recognized in Balance Sheet



	2017						2016
	U.S. Plans			Non-U.S. Plans			U.S. Plans			Non-U.S. Plans
Amounts recognized in the consolidated balance sheet at December 31
Current liabilities	$	(8	)	$	—		$	(8	)	$	—
Noncurrent liabilities	(65		)	(3		)	(72		)	(3		)
Net amount recognized	$	(73	)	$	(3	)	$	(80	)	$	(3	)

Schedule of Amounts Recognized in Other Comprehensive Income (Loss)



	2017					2016
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Amounts recognized in accumulated other comprehensive income (loss)
Net loss	$	(5	)	$	—	$	(4	)	$	—
Total before tax ⁽¹⁾	$	(5	)	$	—	$	(4	)	$	—

______________________________


(1)	After-tax totals for post-retirement healthcare benefits were a loss of $0 and $1 for 2017 and 2016, respectively, and are reflected in stockholders' equity as accumulated other comprehensive income (loss).

Schedule Of Net Benefit Costs And Amounts Recognized In Other Comprehensive Income

The following table provides the components of net periodic benefit costs, other changes in plan assets and benefit obligation recognized in other comprehensive income.



	Year Ended December 31,
	2017					2016					2015
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans
Components of net periodic benefit cost
Service cost	$	1		$	—	$	—		$	—	$	—
Interest cost	2			—		1			—		1
Net amortization	—			—		—			—		—
Net periodic benefit cost	$	3		$	—	$	1		$	—	$	1

Other changes in plan assets and benefit obligation recognized in OCI
Net loss (gain) emerging	$	(1	)	$	—	$	(6	)	$	—	$	(2	)
Total recognized in OCI	$	(1	)	$	—	$	(6	)	$	—	$	(2	)
Total net periodic benefit cost and OCI	$	2		$	—	$	(5	)	$	—	$	(1	)

Schedule Of Weighted Average Assumptions Used

The weighted-average assumptions used to determine post-retirement healthcare plan obligations and net periodic benefit costs for the plans are as follows:



	2017				2016				2015
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans		U.S. Plans
Weighted average assumptions used to determine benefit obligations at December 31
Discount rate	3.0	%	4.0	%	3.3	%	4.0	%	3.5	%
Health care cost trend rate
- Initial rate	7.3	%	6.2	%	7.3	%	6.2	%	—	%
- Ultimate rate	4.5	%	4.5	%	4.5	%	4.5	%	—	%
- Years to ultimate	11		12		11		12		0
Weighted average assumptions used to determine net periodic benefit costs for years ended December 31
Discount rate for benefit obligations	3.3	%	3.3	%	2.6	%	3.3	%	3.3	%
Discount rate for service cost	3.8	%	3.3	%	3.1	%	3.3	%	—	%
Discount rate for interest cost	2.6	%	3.3	%	2.8	%	3.3	%	—	%
Health care cost trend rate
- Initial rate	6.8	%	6.8	%	7.0	%	6.8	%	—	%
- Ultimate rate	4.6	%	4.5	%	4.5	%	4.5	%	—	%
- Years to ultimate	11		12		12		13		0

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Option Activity And Changes

Option activity and changes during the year ended December 31, 2017 were as follows:



	Options		Weighted Average Exercise Price		Weighted Average Remaining Term (Years)	Aggregate Intrinsic Value
Outstanding at December 31, 2016	1,404,734		$	33.76
Granted	289,553		61.87
Exercised	(401,505	)	29.68
Cancelled	(23,181	)	56.92
Outstanding at December 31, 2017	1,269,601		$	41.04	5.9	$	83
Exercisable at December 31, 2017	719,676		$	28.89	3.9	$	56

Schedule Of Range Of Exercise Prices For Outstanding Options

For options outstanding at December 31, 2017, the options had the following range of exercise prices:



Range of Prices	Options Outstanding	Weighted Average Remaining Contractual Life (Years)
$7.12 - $9.65	300,366	1.6
$10.26 - $18.05	167,582	3.6
$22.92 - $30.05	316,601	7.6
$40.38 - $52.35	285,553	9.1
$61.87 - $68.18	199,499	6.8

Schedule Of Weighted Average Value And Assumptions For Fair Value Of Options

The table below presents the weighted average value and assumptions used in determining each option's fair value. Volatility was calculated using historical trends of the Company's common stock price.



	Stock Option Grants
	Year Ended December 31,
	2017			2016			2015
Weighted average fair value	$	15.84		$	11.67		$	20.21
Risk-free interest rate	2.1		%	1.4		%	1.7		%
Expected life in years	5			5			5
Expected volatility	29.2		%	32.9		%	34.2		%
Expected dividend yield	1.2		%	1.6		%	0.9		%

Schedule Of Non-Vested Restricted Stock Award Activity And Changes

Non-vested restricted stock units as of December 31, 2017 and changes during the year ended December 31, 2017 were as follows:



	Number of Units		Weighted Average Grant Date Fair Value
Non-vested at December 31, 2016	597,559		$	55.64
Granted	198,659		62.46
Vested	(91,997	)	61.39
Forfeited	(40,355	)	56.08
Non-vested at December 31, 2017	663,866		$	56.86

on-vested restricted stock awards as of December 31, 2017 and 2016.

Axiall Corporation [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Weighted Average Value And Assumptions For Fair Value Of Options

Volatility was calculated using historical trends of the Company's common stock price.



	Liability Classified Restricted Stock Awards
	Year Ended December 31, 2017
Weighted average vesting period in years	0.8
Risk-free interest rate	1.6	%
Expected volatility	23.1	%
Expected dividend yield	0.8	%

Schedule Of Non-Vested Restricted Stock Award Activity And Changes

Non-vested liability classified restricted stock awards as of December 31, 2017 and changes during the year ended December 31, 2017 were as follows:



	Number of Units		Weighted Average Fair Value
Non-vested at December 31, 2016	286,147		$	60.77
Vested	(161,324	)	65.29
Cancelled	(23,831	)	66.97
Non-vested at December 31, 2017	100,992		$	106.53

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule Of Carrying And Fair Values Of Long-Term Debt

The carrying and fair values of the Company's long-term debt (including the current portion of long-term debt) at December 31, 2017 and 2016 are summarized in the table below. The Company's long-term debt instruments are publicly-traded. A market approach, based upon quotes from financial reporting services, is used to measure the fair value of the Company's long-term debt. Because the Company's long-term debt instruments may not be actively traded, the inputs used to measure the fair value of the Company's long-term debt are classified as Level 2 inputs within the fair value hierarchy.



	2017				2016
	Carrying Value		Fair Value		Carrying Value		Fair Value
Revolving credit facility	$	—	$	—	$	325	$	325
4.625% Westlake 2021 Senior Notes ⁽¹⁾	645		639		652		651
4.625% Subsidiary 2021 Senior Notes ⁽¹⁾	65		65		66		66
3.60% 2022 Senior Notes	249		255		248		252
4.875% Westlake 2023 Senior Notes	445		449		447		451
4.875% Subsidiary 2023 Senior Notes	16		16		17		17
3.60% 2026 Senior Notes	740		757		739		722
Loan related to tax-exempt waste disposal revenue bonds due 2027	11		11		11		11
6 ½% 2029 GO Zone Senior Notes	99		111		99		112
6 ¾% 2032 GO Zone Senior Notes	—		—		248		259
6 ½% 2035 GO Zone Senior Notes	88		99		88		100
6 ½% 2035 IKE Zone Senior Notes	65		74		65		73
5.0% 2046 Senior Notes	675		787		674		692
4.375% 2047 Senior Notes	491		518		—		—
3.50% 2032 Senior Notes	248		256		—		—

___________________________


(1)	The 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes were classified as a component of current liabilities in the consolidated balance sheet at December 31, 2017. For additional information, see Note 9.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Components of Income (Loss) Before Income Taxes

The components of income before income taxes are as follows:



	Year Ended December 31,
	2017		2016		2015
Domestic	$	917	$	476	$	880
Foreign	164		82		83
	$	1,081	$	558	$	963

Schedule of The Provision For (Benefit From) Income Taxes

The Company's provision for (benefit from) income taxes consists of the following:



	Year Ended December 31,
	2017			2016			2015
Current
Federal	$	231		$	8		$	225
State	18			9			24
Foreign	27			20			9
	276			37			258
Deferred
Federal	(557		)	136			30
State	25			(33		)	3
Foreign	(2		)	(2		)	7
	(534		)	101			40
Total provision for (benefit from) income taxes	$	(258	)	$	138		$	298

Reconciliation of Taxes Computed at the Statutory Rate to Income Tax Expense

A reconciliation of taxes computed at the statutory rate to the Company's income tax expense is as follows:



	Year Ended December 31,
	2017			2016			2015
Provision for federal income tax, at statutory rate	$	378		$	195		$	337
State income tax provision, net of federal income tax effect	26			1			17
Foreign income tax rate differential	(33		)	(8		)	(13		)
Manufacturing deduction	(23		)	(2		)	(24		)
Depletion	(7		)	(2		)	—
Noncontrolling interests	(9		)	(7		)	(7		)
Tax on previously held shares of Axiall Corporation and certain other acquisition related items	—			(13		)	—
Tax Act related adjustment	(591		)	—			—
Changes in state apportionment and other state adjustments	2			(17		)	—
Research and development expenditures and adjustments related to prior years' tax returns	(1		)	(8		)	—
Other, net	—			(1		)	(12		)
	$	(258	)	$	138		$	298

Schedule of Deferred Tax Assets And Liabilities

The tax effects of the principal temporary differences between financial reporting and income tax reporting at December 31 are as follows:



	2017			2016
Net operating loss carryforward	$	64		$	70
Credit carryforward	26			24
Accruals	53			67
Pension	79			114
Allowance for doubtful accounts	5			12
Inventories	11			13
Other	15			36
Deferred taxes assets—total	253			336
Property, plant and equipment	(906		)	(1,374		)
Intangibles	(154		)	(221		)
Turnaround costs	(8		)	(1		)
Basis difference—consolidated partnerships	(209		)	(308		)
Other	(18		)	(17		)
Deferred tax liabilities—total	(1,295		)	(1,921		)
Valuation allowance	(56		)	(53		)
Total net deferred tax liabilities	$	(1,098	)	$	(1,638	)

Balance sheet classifications
Noncurrent deferred tax asset	$	13		$	12
Noncurrent deferred tax liability	(1,111		)	(1,650		)
Total net deferred tax liabilities	$	(1,098	)	$	(1,638	)

Earnings per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule Of Net Income Attributable To Common Stockholders

Diluted earnings per share include the effect of certain stock options.



	Year Ended December 31,
	2017			2016			2015
Net income attributable to Westlake Chemical Corporation	$	1,304		$	399		$	646
Less:
Net income attributable to participating securities	(7		)	(2		)	(3		)
Net income attributable to common shareholders	$	1,297		$	397		$	643

Reconciliation Of Denominator For Basic And Diluted Earnings (Loss) Per Share

The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:



	Year Ended December 31,
	2017		2016		2015
Weighted average common shares—basic	129,087,043		129,367,712		131,823,707
Plus incremental shares from:
Assumed exercise of options	452,970		607,110		478,105
Weighted average common shares—diluted	129,540,013		129,974,822		132,301,812

Earnings per common share attributable to Westlake Chemical Corporation:
Basic	$	10.05	$	3.07	$	4.88
Diluted	$	10.00	$	3.06	$	4.86

Supplemental Information (Tables)

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Cash Flow Information

Cash Flow Information



	Year Ended December 31,
	2017		2016		2015
Cash paid for:
Interest paid, net of interest capitalized	$	154	$	46	$	32
Income taxes paid	84		3		314

Commitments And Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Future Minimum Lease Commitments

At December 31, 2017, future minimum lease commitments for operating lease obligations and capital lease obligations were as follows:



	Operating Leases		Capital Leases
2018	$	108	$	3
2019	97		3
2020	73		3
2021	56		2
2022	44		2
Thereafter	651		9
Total minimum lease payments	$	1,029	$	22
Less: Imputed interest costs			(12		)
Present value of net minimum lease payments			$	10

Operating lease rental expense was approximately $147, $87 and $69 for the years ended December 31, 2017, 2016 and 2015, respectively.

Segment And Geographic Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segment Reporting Information



	Year Ended December 31,
	2017			2016			2015
Net external sales
Olefins
Polyethylene	$	1,518		$	1,463		$	1,651
Styrene, feedstock and other	533			431			609
Total olefins	2,051			1,894			2,260
Vinyls
PVC, caustic soda and other	4,769			2,493			1,718
Building products	1,221			689			485
Total vinyls	5,990			3,182			2,203
	$	8,041		$	5,076		$	4,463

Intersegment sales
Olefins	$	393		$	165		$	107
Vinyls	1			26			1
	$	394		$	191		$	108

Income (loss) from operations
Olefins	$	655		$	558		$	747
Vinyls	647			174			255
Corporate and other	(69		)	(151		)	(42		)
	$	1,233		$	581		$	960

Depreciation and amortization
Olefins	$	145		$	136		$	111
Vinyls	449			238			134
Corporate and other	7			4			1
	$	601		$	378		$	246

Other income (expense), net
Olefins	$	3		$	5		$	5
Vinyls	(1		)	3			8
Corporate and other	5			48			25
	$	7		$	56		$	38

Provision for (benefit from) income taxes
Olefins	$	63		$	175		$	243
Vinyls	(302		)	25			64
Corporate and other	(19		)	(62		)	(9		)
	$	(258	)	$	138		$	298

Capital expenditures
Olefins	$	97		$	324		$	305
Vinyls	459			302			176
Corporate and other	21			3			10
	$	577		$	629		$	491

Total Assets



	December 31, 2017		December 31, 2016
Total assets
Olefins	$	2,006	$	2,093
Vinyls	8,853		8,287
Corporate and other	1,217		510
	$	12,076	$	10,890

Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes

A reconciliation of total segment income from operations to consolidated income before income taxes is as follows:



	Year Ended December 31,
	2017			2016			2015
Income from operations for reportable segments	$	1,233		$	581		$	960
Interest expense	(159		)	(79		)	(35		)
Other income, net	7			56			38
Income before income taxes	$	1,081		$	558		$	963

Geographic Information For Sales To External Customers And Long-Lived Assets

Geographic Information



	Year Ended December 31,
	2017		2016		2015
Sales to external customers ⁽¹⁾
United States	$	5,739	$	3,526	$	3,133
Foreign
Canada	653		317		196
Germany	432		402		394
Switzerland	142		101		107
Brazil	108		41		16
China	104		87		46
Italy	96		84		90
Taiwan	96		25		—
Other	671		493		481
	$	8,041	$	5,076	$	4,463



	December 31, 2017		December 31, 2016
Long-lived assets
United States	$	5,668	$	5,783
Foreign
Germany	504		401
Other	240		236
	$	6,412	$	6,420

______________________________


(1)	Revenues are attributed to countries based on location of customer.

Guarantor Disclosures (Tables)

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Condensed Consolidating Financial Information Balance Sheet

Condensed Consolidating Financial Information as of December 31, 2017



	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	1,089	$	57	$	385	$	—		$	1,531
Accounts receivable, net	3,331		4,128		580		(7,038		)	1,001
Inventories	—		654		246		—			900
Prepaid expenses and other current assets	52		26		31		(79		)	30
Restricted cash	—		1		—		—			1
Total current assets	4,472		4,866		1,242		(7,117		)	3,463
Property, plant and equipment, net	—		4,374		2,038		—			6,412
Goodwill	—		855		157		—			1,012
Customer relationships, net	—		479		137		—			616
Other intangible assets, net	—		88		73		—			161
Other assets, net	10,706		798		1,271		(12,363		)	412
Total assets	$	15,178	$	11,460	$	4,918	$	(19,480	)	$	12,076
Current liabilities
Accounts payable	$	6,367	$	864	$	224	$	(6,855	)	$	600
Accrued liabilities	189		484		246		(262		)	657
Current portion of long-term debt, net	710		—		—		—			710
Total current liabilities	7,266		1,348		470		(7,117		)	1,967
Long-term debt, net	3,034		4,242		220		(4,369		)	3,127
Deferred income taxes	—		1,026		92		(7		)	1,111
Pension and other liabilities	4		347		151		—			502
Total liabilities	10,304		6,963		933		(11,493		)	6,707
Total Westlake Chemical Corporation stockholders' equity	4,874		4,497		3,490		(7,987		)	4,874
Noncontrolling interests	—		—		495		—			495
Total equity	4,874		4,497		3,985		(7,987		)	5,369
Total liabilities and equity	$	15,178	$	11,460	$	4,918	$	(19,480	)	$	12,076

Condensed Consolidating Financial Information as of December 31, 2016



	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	147	$	53	$	259	$	—		$	459
Accounts receivable, net	2,118		3,330		324		(4,833		)	939
Inventories	—		598		203		—			801
Prepaid expenses and other current assets	31		42		12		(37		)	48
Restricted cash	—		—		161		—			161
Total current assets	2,296		4,023		959		(4,870		)	2,408
Property, plant and equipment, net	—		4,476		1,944		—			6,420
Goodwill	—		792		155		—			947
Customer relationships, net	—		468		143		—			611
Other intangible assets, net	—		131		70		(25		)	176
Other assets, net	9,170		874		1,116		(10,832		)	328
Total assets	$	11,466	$	10,764	$	4,387	$	(15,727	)	$	10,890
Current liabilities
Accounts payable	$	4,331	$	748	$	225	$	(4,808	)	$	496
Accrued liabilities	26		390		183		(61		)	538
Term loan	—		—		149		—			149
Total current liabilities	4,357		1,138		557		(4,869		)	1,183
Long-term debt, net	3,585		4,091		—		(3,997		)	3,679
Deferred income taxes	—		1,581		92		(23		)	1,650
Pension and other liabilities	—		361		125		—			486
Total liabilities	7,942		7,171		774		(8,889		)	6,998
Total Westlake Chemical Corporation stockholders' equity	3,524		3,593		3,245		(6,838		)	3,524
Noncontrolling interests	—		—		368		—			368
Total equity	3,524		3,593		3,613		(6,838		)	3,892
Total liabilities and equity	$	11,466	$	10,764	$	4,387	$	(15,727	)	$	10,890

Condensed Consolidating Financial Information Statement Of Operations

Condensed Consolidating Financial Information for the Year Ended December 31, 2017



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	6,650		$	3,143		$	(1,752	)	$	8,041
Cost of sales	—			5,559			2,438			(1,725		)	6,272
Gross profit	—			1,091			705			(27		)	1,769
Selling, general and administrative expenses	3			292			131			(27		)	399
Amortization of intangibles	1			81			26			—			108
Transaction and integration-related costs	—			27			2			—			29
Income (loss) from operations	(4		)	691			546			—			1,233
Other income (expense)
Interest expense	(154		)	(178		)	(6		)	179			(159		)
Other income (expense), net	154			(3		)	35			(179		)	7
Income (loss) before income taxes	(4		)	510			575			—			1,081
Provision for (benefit from) income taxes	10			(312		)	44			—			(258		)
Equity in net income of subsidiaries	1,318			—			—			(1,318		)	—
Net income (loss)	1,304			822			531			(1,318		)	1,339
Net income attributable to noncontrolling interests	—			—			35			—			35
Net income (loss) attributable to Westlake Chemical Corporation	$	1,304		$	822		$	496		$	(1,318	)	$	1,304
Comprehensive income attributable to Westlake Chemical Corporation	$	1,432		$	833		$	493		$	(1,326	)	$	1,432

Condensed Consolidating Financial Information for the Year Ended December 31, 2016



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	4,010		$	2,445		$	(1,379	)	$	5,076
Cost of sales	—			3,533			1,919			(1,357		)	4,095
Gross profit	—			477			526			(22		)	981
Selling, general and administrative expenses	2			178			100			(22		)	258
Amortization of intangibles	1			27			10			—			38
Transaction and integration-related costs	—			103			1			—			104
Income (loss) from operations	(3		)	169			415			—			581
Other income (expense)
Interest expense	(83		)	(76		)	(2		)	82			(79		)
Other income (expense), net	77			(14		)	75			(82		)	56
Income (loss) before income taxes	(9		)	79			488			—			558
Provision for (benefit from) income taxes	(8		)	115			31			—			138
Equity in net income of subsidiaries	400			—			—			(400		)	—
Net income (loss)	399			(36		)	457			(400		)	420
Net income attributable to noncontrolling interests	—			—			21			—			21
Net income (loss) attributable to Westlake Chemical Corporation	$	399		$	(36	)	$	436		$	(400	)	$	399
Comprehensive income attributable to Westlake Chemical Corporation	$	407		$	11		$	396		$	(407	)	$	407

Condensed Consolidating Financial Information for the Year Ended December 31, 2015



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	3,558		$	2,286	$	(1,381	)	$	4,463
Cost of sales	—			2,842			1,797		(1,361		)	3,278
Gross profit	—			716			489		(20		)	1,185
Selling, general and administrative expenses	3			146			89		(20		)	218
Amortization of intangibles	—			5			2		—			7
Income (loss) from operations	(3		)	565			398		—			960
Other income (expense)
Interest expense	(42		)	(35		)	—		42			(35		)
Other income (expense), net	20			5			55		(42		)	38
Income (loss) before income taxes	(25		)	535			453		—			963
Provision for (benefit from) income taxes	(7		)	275			30		—			298
Equity in net income of subsidiaries	664			—			—		(664		)	—
Net income (loss)	646			260			423		(664		)	665
Net income attributable to noncontrolling interests	—			—			19		—			19
Net income (loss) attributable to Westlake Chemical Corporation	$	646		$	260		$	404	$	(664	)	$	646
Comprehensive income attributable to Westlake Chemical Corporation	$	596		$	261		$	335	$	(596	)	$	596

Condensed Consolidating Financial Information Statement Of Cash Flows

Condensed Consolidating Financial Information for the Year Ended December 31, 2017



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	1,304		$	822		$	531		$	(1,318	)	$	1,339
Adjustments to reconcile net income to net cash provided by (used for) operating activities
Depreciation and amortization	—			395			206			—			601
Deferred income taxes	12			(535		)	(11		)	—			(534		)
Net changes in working capital and other	(1,327		)	41			100			1,318			132
Net cash provided by (used for) operating activities	(11		)	723			826			—			1,538
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			(13		)	—			—			(13		)
Additions to property, plant and equipment	—			(407		)	(170		)	—			(577		)
Additions to cost method investment	—			(66		)	—			—			(66		)
Other	—			2			(134		)	136			4
Net cash provided by (used for) investing activities	—			(484		)	(304		)	136			(652		)
Cash flows from financing activities
Intercompany financing	746			(611		)	(135		)	—			—
Receivable under the investment management agreement	136			—			—			(136		)	—
Debt issuance costs	(6		)	—			—			—			(6		)
Dividends paid	(103		)	—			—			—			(103		)
Distributions to noncontrolling interests	—			376			(404		)	—			(28		)
Proceeds from debt issuance and drawdown of revolver	225			—			8			—			233
Net proceeds from issuance of Westlake Chemical Partners LP common units	—			—			111			—			111
Proceeds from senior notes issuance	745			—			—			—			745
Repayment of term loan	—			—			(150		)	—			(150		)
Restricted cash associated with term loan	—			—			154			—			154
Repayment of revolver	(550		)	—			—			—			(550		)
Repayment of notes payable	(251		)	—			(6		)	—			(257		)
Other	11			—			—			—			11
Net cash provided by (used for) financing activities	953			(235		)	(422		)	(136		)	160



	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	—		—		26		—		26
Net increase (decrease) in cash and cash equivalents	942		4		126		—		1,072
Cash and cash equivalents at beginning of the year	147		53		259		—		459
Cash and cash equivalents at end of the year	$	1,089	$	57	$	385	$	—	$	1,531

Condensed Consolidating Financial Information for the Year Ended December 31, 2016



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	399		$	(36	)	$	457		$	(400	)	$	420
Adjustments to reconcile net income to net cash provided by (used for) operating activities
Depreciation and amortization	—			217			161			—			378
Deferred income taxes	1			103			(3		)	—			101
Net changes in working capital and other	(437		)	90			(118		)	400			(65		)
Net cash provided by (used for) operating activities	(37		)	374			497			—			834
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			(2,502		)	64			—			(2,438		)
Additions to property, plant and equipment	—			(275		)	(354		)	—			(629		)
Additions to cost method investments	—			(17		)	—			—			(17		)
Proceeds from sales and maturities of securities	658			—			5			—			663
Purchase of securities	(138		)	—			—			—			(138		)
Other	—			(4		)	—			—			(4		)
Net cash provided by (used for) investing activities	520			(2,798		)	(285		)	—			(2,563		)
Cash flows from financing activities
Intercompany financing	(2,199		)	2,207			(8		)	—			—
Debt issuance costs	(35		)	—			(1		)	—			(36		)
Dividends paid	(97		)	—			—			—			(97		)
Distributions paid	—			263			(280		)	—			(17		)
Proceeds from debt issuance and drawdown of revolver	450			—			158			—			608
Proceeds from senior notes issuance	1,429			—			—			—			1,429
Restricted cash associated with term loan	—			—			(154		)	—			(154		)
Repayment of revolver	(125		)	—			—			—			(125		)
Repayment of notes payable	—			—			(13		)	—			(13		)
Repurchase of common stock for treasury	(67		)	—			—			—			(67		)
Other	5			—			—			—			5
Net cash provided by (used for) financing activities	(639		)	2,470			(298		)	—			1,533



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	—			—		(8		)	—		(8		)
Net increase (decrease) in cash and cash equivalents	(156		)	46		(94		)	—		(204		)
Cash and cash equivalents at beginning of the year	303			7		353			—		663
Cash and cash equivalents at end of the year	$	147		$	53	$	259		$	—	$	459

Condensed Consolidating Financial Information for the Year Ended December 31, 2015



	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	646		$	260		$	423		$	(664	)	$	665
Adjustments to reconcile net income to net cash provided by (used for) operating activities
Depreciation and amortization	—			114			132			—			246
Deferred income taxes	—			39			1			—			40
Net changes in working capital and other	(659		)	93			30			664			128
Net cash provided by (used for) operating activities	(13		)	506			586			—			1,079
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			—			16			—			16
Additions to property, plant and equipment	—			(215		)	(276		)	—			(491		)
Proceeds from disposition of equity method investments	—			28			—			—			28
Proceeds from sales and maturities of securities	49			—			—			—			49
Purchase of securities	(556		)	(49		)	—			—			(605		)
Other	—			(3		)	—			—			(3		)
Net cash used for investing activities	(507		)	(239		)	(260		)	—			(1,006		)
Cash flows from financing activities
Intercompany financing	418			(590		)	172			—			—
Dividends paid	(92		)	—			—			—			(92		)
Distributions paid	—			327			(342		)	—			(15		)
Proceeds from debt issuance	—			—			53			—			53
Repayment of notes payable	—			—			(74		)	—			(74		)
Repurchase of common stock for treasury	(163		)	—			—			—			(163		)
Other	4			—			—			—			4
Net cash provided by (used for) financing activities	167			(263		)	(191		)	—			(287		)
Effect of exchange rate changes on cash and cash equivalents	—			—			(4		)	—			(4		)
Net increase (decrease) in cash and cash equivalents	(353		)	4			131			—			(218		)
Cash and cash equivalents at beginning of the year	656			3			222			—			881
Cash and cash equivalents at end of the year	$	303		$	7		$	353		$	—		$	663

Quarterly Financial Information (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Summary Of Quarterly Financial Information



	Three Months Ended
	March 31, 2017		June 30, 2017		September 30, 2017		December 31, 2017
Net sales	$	1,943	$	1,979	$	2,109	$	2,010
Gross profit	368		405		498		498
Income from operations	236		266		366		365
Net income	145		159		219		816
Net income attributable to Westlake Chemical Corporation	138		153		211		802
Earnings per common share attributable to Westlake Chemical Corporation: ⁽¹⁾
Basic	$	1.07	$	1.18	$	1.62	$	6.18
Diluted	$	1.06	$	1.17	$	1.61	$	6.15

	Three Months Ended
	March 31, 2016		June 30, 2016		September 30, 2016		December 31, 2016
Net sales	$	975	$	1,086	$	1,280	$	1,735
Gross profit	255		241		203		282
Income from operations	202		180		46		153
Net income	129		116		70		105
Net income attributable to Westlake Chemical Corporation	123		111		66		99
Earnings per common share attributable to Westlake Chemical Corporation: ⁽¹⁾
Basic	$	0.94	$	0.85	$	0.51	$	0.76
Diluted	$	0.94	$	0.85	$	0.51	$	0.76

______________________________


(1)	Basic and diluted earnings per common share ("EPS") for each quarter is computed using the weighted average shares outstanding during that quarter, while EPS for the year is computed using the weighted average shares outstanding for the year. As a result, the sum of the EPS for each of the four quarters may not equal the EPS for the year.

Description Of Business And Significant Accounting Policies (Narrative) (Details) $ / shares in Units, $ in Millions			3 Months Ended	12 Months Ended
	Sep. 29, 2017	Aug. 04, 2014	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($) plant	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Aug. 31, 2016 USD ($) $ / shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Provisional adjustment of income tax benefit				$ 591
Aggregate principal amount of senior notes			$ 1,450
Capitalized interest				4	$ 10	$ 10
Asset Retirement Obligation, Current				3	4
Asset Retirement Obligations, Noncurrent				$ 18	$ 17
Westlake Chemical OpCo LP [Member] \| Limited Partner [Member] \| IPO [Member] \| Subsidiary of Common Parent [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Limited partner interest (percent)	81.70%	89.40%		81.70%
Westlake Chemical OpCo LP [Member] \| Subsidiaries [Member] \| Louisiana
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of production facilities \| plant				2
Westlake Chemical OpCo LP [Member] \| Subsidiaries [Member] \| Kentucky
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of production facilities \| plant				1
Revolving Credit Facility [Member] \| Senior Secured Revolving Credit Facility [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Maximum borrowing capacity				$ 1,000			$ 1,000
Axiall Corporation [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Share price (in dollars per share) \| $ / shares							$ 33.00

Description Of Business And Significant Accounting Policies (Schedule Of Estimated Useful Lives Of Assets) (Details)	12 Months Ended
	Dec. 31, 2017
Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	40 years
Plant And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	25 years
Ethylene Pipeline [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	35 years
Minimum [Member] \| Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	3 years
Maximum [Member] \| Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	15 years

Acquisitions (Narrative) (Details) $ / shares in Units, shares in Thousands, lb in Millions, $ in Millions				4 Months Ended	12 Months Ended
	Aug. 31, 2016 USD ($) $ / shares	Aug. 30, 2016 shares	Jun. 01, 2015 USD ($) lb	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	May 31, 2015
Business Acquisition [Line Items]
Transaction and integration-related costs					$ 29	$ 104	$ 0
Goodwill				$ 947	$ 1,012	947	62
Ownership Percentage held prior to acquisition					100.00%
Axiall Corporation [Member]
Business Acquisition [Line Items]
Equity interest in acquiree held prior to combination, shares \| shares		3,100
Offer price per share (usd per share) \| $ / shares	$ 33.00
Purchase price	$ 2,540
Professional fees				49		49
Share-based awards, Retention & Severance						55
Contribution to net sales				976
Contribution to net loss				$ 96
Goodwill	$ 942
Remeasurement gain (loss)						$ 49
Suzhou Huasu Plastics Company Ltd [Member]
Business Acquisition [Line Items]
Remeasurement gain (loss)							$ (2)
Fair value of consideration transferred-cash			$ 6
Bargain purchase gain on acquisition			$ 23
Suzhou Huasu Plastics Company Ltd [Member] \| PVC Resin [Member]
Business Acquisition [Line Items]
Combined annual capacity (in lb's) \| lb			300
Suzhou Huasu Plastics Company Ltd [Member] \| PVC Film [Member]
Business Acquisition [Line Items]
Combined annual capacity (in lb's) \| lb			145
Suzhou Huasu Plastics Company Ltd [Member] \| Affiliates [Member]
Business Acquisition [Line Items]
Percentage of interests acquired			35.70%
Percentage of interest held after acquisition			95.00%
Ownership Percentage held prior to acquisition								59.30%

Acquisitions (Allocation of Purchase Consideration) (Details) - Axiall Corporation [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Millions			12 Months Ended
	Aug. 31, 2016	Aug. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Offer price per share (usd per share)	$ 33.00
Multiplied by number of shares outstanding at acquisition (in thousands of shares)	67,277
Fair value of Axiall shares outstanding purchased by the Company	$ 2,220
Axiall debt repaid at acquisition	247
Seller's transaction costs paid by the Company	48
Total fair value of consideration transferred	2,515
Fair value of Axiall share-based awards attributed to pre-combination service	12
Additional settlement value of shares acquired	13
Purchase consideration	2,540
Fair value of previously held equity interest in Axiall	102
Total fair value allocated to net assets acquired	$ 2,642
Equity interest in acquiree held prior to combination, shares		3,100
Remeasurement gain (loss)			$ 49

Acquisitions (Purchase Price Allocation) (Details) - USD ($) $ in Millions		12 Months Ended
	Aug. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 1,012	$ 947	$ 62
Goodwill, Purchase Accounting Adjustments		$ 55
Customer relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	9 years 9 months 18 days
Trade Name [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 9 months 18 days
Technology [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years 4 months 24 days
Supply Contracts and Leases [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 3 months 18 days
Axiall Corporation [Member]
Business Acquisition [Line Items]
Cash	$ 88
Accounts Receivable	422
Income tax receivable	51
Inventories	349
Prepaid expenses and other current assets	56
Property, plant and equipment	2,942
Other assets	94
Total assets acquired	4,791
Accounts and notes payable	254
Interest payable	8
Income tax payable	2
Accrued compensation	44
Accrued liabilities	154
Deferred income taxes	958
Tax reserve non-current	3
Pension and other post retirement obligations	311
Other liabilities	102
Long-term debt	1,187
Total liabilities assumed	3,023
Total identifiable net assets acquired	1,768
Noncontrolling interest	(68)
Goodwill	942
Total fair value allocated to net assets acquired	2,642
Business Combination, Acquired Receivables, Gross Contractual Amount	435
Business Combination, Acquired Receivables, Estimated Uncollectible	13
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory	43
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment	(193)
Goodwill, Purchase Accounting Adjustments	150
Axiall Corporation [Member] \| Customer relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangibles	670
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles	80
Axiall Corporation [Member] \| Trade Name [Member]
Business Acquisition [Line Items]
Finite-lived intangibles	50
Axiall Corporation [Member] \| Technology [Member]
Business Acquisition [Line Items]
Finite-lived intangibles	42
Axiall Corporation [Member] \| Supply Contracts and Leases [Member]
Business Acquisition [Line Items]
Finite-lived intangibles	27
Deferred Income Tax [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period	$ (27)

Acquisitions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	8 Months Ended	12 Months Ended
	Aug. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Net sales		$ 7,081	$ 7,793
Net income		397	663
Net income (loss) attributable to noncontrolling interest		23	(2)
Net income attributable to Westlake Chemical Corporation		$ 374	$ 665
Basic (in dollars per share)		$ 2.88	$ 5.02
Diluted (in dollars per share)		$ 2.86	$ 5.00
Axiall Corporation [Member]
Business Acquisition [Line Items]
Divestitures	$ 27
Restructuring Costs	23
Legal and Settlement Claims, net	$ 23

Financial Instruments (Cash Equivalents and Restricted Cash) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Held-to-maturity Securities	$ 644	$ 0
Restricted cash and cash equivalents	23	186
Restricted cash and cash equivalents current	1	161
Restricted cash and cash equivalents noncurrent	$ 22	$ 25

Financial Instruments (Available-for-Sale Marketable Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Total Available-for-sale Securities	$ 0	$ 0
Proceeds from sales and maturities of securities	0	663	$ 49
Gross realized gains	$ 0	$ 54	$ 4

Accounts Receivable (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Trade customers	$ 974	$ 820
Affiliates	9	8
Allowance for doubtful accounts	(22)	(18)
Accounts Receivable from trade customers, net	961	810
Federal and state taxes	7	90
Other	33	39
Accounts receivable, net	$ 1,001	$ 939

Inventories (Schedule Of Inventory) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory, Net [Abstract]
Finished products	$ 549	$ 501
Feedstock, additives and chemicals	221	217
Materials and supplies	130	83
Inventories	$ 900	$ 801

Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment, Net [Abstract]
Land	$ 198	$ 194
Buildings and improvements	495	465
Plant and equipment	7,281	6,914
Other	388	377
Property, Plant and Equipment, Gross	8,362	7,950
Less: Accumulated depreciation	(2,338)	(1,919)
Property, plant and equipment, net, before construction in progress	6,024	6,031
Construction in progress	388	389
Property, plant and equipment, net	$ 6,412	$ 6,420

Property, Plant And Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment, Net [Abstract]
Depreciation expense on property, plant and equipment	$ 449	$ 305	$ 209

Goodwill, Intangibles and Other Assets (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017
Olefins [Member]
Other Assets [Line Items]
Number of years forecasted to test for impairment of goodwill	9 years
Olefins [Member] \| Discounted Cash Flow and Market Approach Valuation Technique [Member]
Other Assets [Line Items]
Discount rate	8.00%
Vinyls [Member]
Other Assets [Line Items]
Number of years forecasted to test for impairment of goodwill	9 years
Vinyls [Member] \| Market Approach Valuation Technique [Member] \| Minimum [Member]
Other Assets [Line Items]
Discount rate	9.00%
Vinyls [Member] \| Market Approach Valuation Technique [Member] \| Maximum [Member]
Other Assets [Line Items]
Discount rate	12.00%

Goodwill, Intangibles and Other Assets (Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at beginning of year	$ 947	$ 62
Goodwill acquired during the year		888
Effects of changes in foreign exchange rates	10	(3)
Goodwill, Purchase Accounting Adjustments	55
Balance at end of year	1,012	947
Olefins [Member]
Goodwill [Roll Forward]
Balance at beginning of year	30	30
Goodwill acquired during the year		0
Effects of changes in foreign exchange rates	0	0
Goodwill, Purchase Accounting Adjustments	0
Balance at end of year	30	30
Vinyls [Member]
Goodwill [Roll Forward]
Balance at beginning of year	917	32
Goodwill acquired during the year		888
Effects of changes in foreign exchange rates	10	(3)
Goodwill, Purchase Accounting Adjustments	55
Balance at end of year	$ 982	$ 917

Goodwill, Intangibles and Other Assets (Schedule Finite-Lived Intanible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Net	$ 616	$ 611
Customer relationships [Member]
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-Lived Customer Relationships, Gross	754	662
Intangible assets, Accumulated Amortization	(138)	(51)
Net	$ 616	611
Weighted Average Life	10 years
Licenses and intellectual property [Member]
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-Lived License Agreements, Gross	$ 124	121
Intangible assets, Accumulated Amortization	(55)	(44)
Net	$ 69	77
Weighted Average Life	13 years
Trademarks [Member]
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-Lived Trademarks, Gross	$ 93	88
Intangible assets, Accumulated Amortization	(17)	(7)
Net	$ 76	81
Weighted Average Life	13 years
Other [Member]
Goodwill and Intangible Assets Disclosure [Abstract]
Other Intangible Assets, Gross	$ 31	31
Intangible assets, Accumulated Amortization	(15)	(13)
Net	$ 16	18
Weighted Average Life	12 years
Total Other Intangible Assets [Member]
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets, Cost	$ 248	240
Intangible assets, Accumulated Amortization	(87)	(64)
Net	$ 161	$ 176

Goodwill, Intangibles and Other Assets (Amortization) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2018	$ 107
2019	106
2020	105
2021	103
2022	$ 81

Term Loan (Narrative) (Details) - Term Loan Facility Maturing March 31, 2017 [Member] $ in Millions	Aug. 10, 2016 USD ($)
Term Loan [Line Items]
Note Payable to Bank Borrowing	$ 150
LIBOR [Member]
Term Loan [Line Items]
Basis spread on variable rate	2.00%

Long-Term Debt (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2017	Nov. 30, 2017	Dec. 31, 2016	Aug. 10, 2016	Jul. 31, 2012	Dec. 31, 2010
Debt Instrument [Line Items]
Principal amount		$ 3,853		$ 3,678
Unamortized Premium (Discount) and Debt Issuance Costs		(16)		1
Long-term debt, net		3,837		3,679
Long-Term Debt, Gross, Current Maturities		688		0
Debt Instrument, Unamortized Premium (Discount) and debt issuance cost, net, Current Maturities		22		0
Long-term Debt, Current Maturities		710		0
Long-term Debt, Gross Excluding Current Maturities		3,165		3,678
Debt Instrument, Unamortized Premium (Discount) and Debt Issuance Cost, Net, Excluding Current Maturities		(38)		1
Long-term Debt, Excluding Current Maturities		3,127		3,679
Senior Secured Revolving Credit Facility [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal amount		0		325
Unamortized Premium (Discount) and Debt Issuance Costs		0		0
Long-term debt, net		$ 0		325
Senior Notes [Member] \| 4.625% Westlake Senior Notes 2021 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2021
Stated interest rate (percent)		4.625%
Principal amount	$ 625	$ 625		625
Unamortized Premium (Discount) and Debt Issuance Costs		20		27
Long-term debt, net		$ 645		652
Senior Notes [Member] \| 4.625% Subsidiary Senior Notes 2021 [Member]
Debt Instrument [Line Items]
Debt instrument maturity	2021	2021
Stated interest rate (percent)	4.625%	4.625%
Principal amount	$ 688	$ 63		63
Unamortized Premium (Discount) and Debt Issuance Costs		2		3
Long-term debt, net		$ 65		66
Senior Notes [Member] \| 3.60% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2022
Stated interest rate (percent)		3.60%
Principal amount		$ 250		250		$ 250
Unamortized Premium (Discount) and Debt Issuance Costs		(1)		(2)
Long-term debt, net		$ 249		248
Senior Notes [Member] \| 4.875% Westlake Senior 2023 Notes [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2023
Stated interest rate (percent)		4.875%
Principal amount	$ 434	$ 434		434
Unamortized Premium (Discount) and Debt Issuance Costs		11		13
Long-term debt, net		$ 445		447
Senior Notes [Member] \| 4.875% Subsidiary 2023 Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument maturity	2023	2023
Stated interest rate (percent)	4.875%	4.875%
Principal amount	$ 450	$ 16		16
Unamortized Premium (Discount) and Debt Issuance Costs		0		1
Long-term debt, net		$ 16		17
Senior Notes [Member] \| 3.60% Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2026
Stated interest rate (percent)		3.60%
Principal amount		$ 750		750	$ 750
Unamortized Premium (Discount) and Debt Issuance Costs		(10)		(11)
Long-term debt, net		$ 740		739
Senior Notes [Member] \| Waste Disposal Revenue Bonds Due 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2027
Principal amount		$ 11		11
Unamortized Premium (Discount) and Debt Issuance Costs		0		0
Long-term debt, net		$ 11		11
Senior Notes [Member] \| 6 1/2% GO Zone Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2029
Stated interest rate (percent)		6.50%
Principal amount		$ 100		100
Unamortized Premium (Discount) and Debt Issuance Costs		(1)		(1)
Long-term debt, net		$ 99		99
Senior Notes [Member] \| 6.75% Go Zone Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2032
Stated interest rate (percent)		6.75%
Principal amount		$ 0		250
Unamortized Premium (Discount) and Debt Issuance Costs		0		(2)
Long-term debt, net		$ 0		248
Senior Notes [Member] \| 6 1/2% GO Zone Tax-Exempt Revenue Bonds Due 2035 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2035
Stated interest rate (percent)		6.50%
Principal amount		$ 89		89			$ 89
Unamortized Premium (Discount) and Debt Issuance Costs		(1)		(1)
Long-term debt, net		$ 88		88
Senior Notes [Member] \| 6.5% 2035 IKE Zone Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2035
Stated interest rate (percent)		6.50%
Principal amount		$ 65		65			$ 65
Unamortized Premium (Discount) and Debt Issuance Costs		0		0
Long-term debt, net		$ 65		65
Senior Notes [Member] \| 5.0% 2046 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2046
Stated interest rate (percent)		5.00%
Principal amount		$ 700		700
Unamortized Premium (Discount) and Debt Issuance Costs		(25)		(26)
Long-term debt, net		$ 675		674
Senior Notes [Member] \| 4.375% Senior Notes Due 2047 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2047
Stated interest rate (percent)		4.375%
Principal amount		$ 500	$ 500	0
Unamortized Premium (Discount) and Debt Issuance Costs		(9)		0
Long-term debt, net		$ 491		0
Senior Notes [Member] \| 3.50% Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Debt instrument maturity		2032
Stated interest rate (percent)		3.50%
Principal amount		$ 250		0
Unamortized Premium (Discount) and Debt Issuance Costs		(2)		0
Long-term debt, net		$ 248		$ 0

Long-Term Debt (Credit Agreement (Details) - Revolving Credit Facility [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Aug. 31, 2016
Senior Secured Revolving Credit Facility [Member]
Term Loan [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000	$ 1,000
Line of Credit Facility, Fair Value of Amount Outstanding	0
Letters of Credit Outstanding, Amount	6
Line of Credit Facility, Remaining Borrowing Capacity	$ 994
Minimum [Member] \| LIBOR [Member]
Term Loan [Line Items]
Basis spread on variable rate	1.00%
Minimum [Member] \| Alternate Base Rate [Domain]
Term Loan [Line Items]
Basis spread on variable rate	0.00%
Maximum [Member] \| LIBOR [Member]
Term Loan [Line Items]
Basis spread on variable rate	1.75%
Maximum [Member] \| Alternate Base Rate [Domain]
Term Loan [Line Items]
Basis spread on variable rate	0.75%

Long-Term Debt (Senior Notes Due 2026 and 2046) (Details) - USD ($) $ in Millions	Apr. 24, 2017	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Aug. 10, 2016
Debt Instrument [Line Items]
Principal amount		$ 3,853	$ 3,678
3.60% Senior Notes Due 2026 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount		750	750		$ 750
Exchange Offer Percentage	99.97%
5.0% Senior Notes Due 2046 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount					$ 700
4.875% Westlake Senior 2023 Notes [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount		$ 434	$ 434	$ 434
Exchange Offer Percentage	100.00%

Long-Term Debt (Senior Notes Due 2021 and 2023) (Details) - USD ($) $ in Millions			1 Months Ended	12 Months Ended
	Feb. 15, 2018	Apr. 24, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Gross				$ 3,853	$ 3,678
Senior Notes [Member] \| 4.625% Westlake Senior Notes 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 625	$ 625	625
Stated interest rate (percent)				4.625%
Debt instrument maturity				2021
Exchange Offer Percentage		100.00%
Senior Notes [Member] \| 4.875% Westlake Senior 2023 Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			434	$ 434	434
Stated interest rate (percent)				4.875%
Debt instrument maturity				2023
Exchange Offer Percentage		100.00%
Senior Notes [Member] \| 4.625% Subsidiary Senior Notes 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 688	$ 63	63
Stated interest rate (percent)			4.625%	4.625%
Debt instrument maturity			2021	2021
Senior Notes [Member] \| 4.875% Subsidiary 2023 Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 450	$ 16	$ 16
Stated interest rate (percent)			4.875%	4.875%
Debt instrument maturity			2023	2023
Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	102.313%

Long-Term Debt (3.60% Senior Notes due 2022) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Jul. 31, 2012
Debt Instrument [Line Items]
Principal amount	$ 3,853	$ 3,678
Senior Notes [Member]
Debt Instrument [Line Items]
Minimum Debt Amount Guaranteed By Subsidiaries	5
Senior Notes [Member] \| 3.60% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Principal amount	$ 250	$ 250	$ 250
Debt Instrument, Unamortized Discount			1
Minimum Debt Amount Guaranteed By Subsidiaries			$ 5

Long-Term Debt (4.375% Senior Notes due 2047) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Nov. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 3,853		$ 3,678
Senior Notes [Member]
Debt Instrument [Line Items]
Minimum debt amount guaranteed by subsidiaries	5
Senior Notes [Member] \| 4.375% Senior Notes Due 2047 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 500	$ 500	$ 0
Minimum debt amount guaranteed by subsidiaries		$ 40

Long-Term Debt (IKE Zone Bonds) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2010
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 3,853	$ 3,678
Senior Notes [Member] \| 6.5% 2035 IKE Zone Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 65	$ 65	$ 65

Long-Term Debt (GO Zone Bonds) (Details) $ in Millions		12 Months Ended
Long-Term Debt (GO Zone Bonds) (Details) $ in Millions	Nov. 01, 2017 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2010 USD ($)	Jul. 02, 2010 USD ($)	Dec. 13, 2007 USD ($)
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 3,853		$ 3,678
Senior Notes [Member]
Debt Instrument [Line Items]
Minimum Debt Amount Guaranteed By Subsidiaries		5
Senior Notes [Member] \| 6 1/2% GO Zone Tax-Exempt Revenue Bonds Due 2035 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 89		89	$ 89
Debt Instrument, Face Amount							$ 250
Stated interest rate (percent)		6.50%
Senior Notes [Member] \| 6.75% Go Zone Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 0		250
Debt Instrument, Face Amount					$ 89
Extinguishment of Debt, Amount	$ 250
Stated interest rate (percent)		6.75%
Senior Notes [Member] \| Go Zone 3.50% Bonds Due 2032 [Member]
Debt Instrument [Line Items]
Amount of bonds remarketed			$ 250
Stated interest rate (percent)			3.50%
Senior Notes [Member] \| 6 1/2% GO Zone Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 100		100
Debt Instrument, Face Amount						$ 100
Stated interest rate (percent)		6.50%
Senior Notes [Member] \| 3.50% Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 250		0
Stated interest rate (percent)		3.50%
Minimum Debt Amount Guaranteed By Subsidiaries		$ 40
Fixed Charge Coverage Ratio		2.0
Maximum Unrestricted Quarterly Dividends Allowable Under Debt Covenants		0.10
Maximum Unrestricted Distributions Allowable Under Debt Covenants		$ 100
Maximum Percentage Of Income Distribution		50.00%
Maximum Distribution Percentage Of Specified Net Cash Proceeds		100.00%
Senior Notes [Member] \| Waste Disposal Revenue Bonds Due 2027 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 11		$ 11

Long-Term Debt (Revenue Bonds) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 3,853	$ 3,678
Weighted average interest rate on all long-term debt	4.50%	4.40%
Unamortized Debt Issuance Cost	$ 26	$ 24
Long-term Debt, Maturities, Repayments of Principal in Year Five	250
Long-term Debt, Maturities, Repayments of Principal in Year Two	0
Long-term Debt, Maturities, Repayments of Principal in Year Three	0
Long-term Debt, Maturities, Repayments of Principal in Year Four	0
Waste Disposal Revenue Bonds Due 2027 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 11	$ 11
Debt Instrument, Interest Rate, Effective Percentage	1.73%	0.79%

Stockholders' Equity (Details) $ in Millions	12 Months Ended
Stockholders' Equity (Details) $ in Millions	Dec. 31, 2017 USD ($) vote shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Nov. 20, 2015 USD ($)	Mar. 31, 2015 USD ($) shares	Nov. 30, 2014 USD ($)	Aug. 31, 2011 USD ($)
Class of Stock [Line Items]
Dividends, Common Stock, Cash	$ 103	$ 97	$ 92
Common Stock, Voting Rights, Number of Votes Per Share \| vote	1
Common stock, sinking fund	$ 0
2011 Program [Member]
Class of Stock [Line Items]
Stock repurchase program, authorized amount							$ 100
Stock repurchased 2011 program, shares repurchased \| shares					1,944,161
Aggregate purchase price of common stock repurchased					$ 100
2014 Program [Member]
Class of Stock [Line Items]
Stock repurchase program, authorized amount				$ 150		$ 250
Stock repurchased 2014 program, shares repurchase \| shares	0	1,511,109
Ordinary Dividend [Member]
Class of Stock [Line Items]
Dividends, Common Stock, Cash	$ 103	$ 97	$ 92

Accumulated Other Comprehensive Income (Loss) Changes in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total equity, beginning balance	$ 3,892	$ 3,562	$ 3,202
Other comprehensive income (loss)	133	8	(50)
Comprehensive income attributable to Westlake Chemical Corporation	1,432	407	596
Total equity, ending balance	5,369	3,892	3,562
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total equity, beginning balance	(121)	(129)	(79)
Other comprehensive income (loss) before reclassifications	126	59
Amounts reclassified from accumulated other comprehensive income (loss)	2	(51)
Other comprehensive income (loss)	128	8	(50)
Total equity, ending balance	7	(121)	(129)
Benefits Liability, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total equity, beginning balance	29	(8)
Other comprehensive income (loss) before reclassifications	12	36
Amounts reclassified from accumulated other comprehensive income (loss)	2	1
Other comprehensive income (loss)	14	37
Total equity, ending balance	43	29	(8)
Cumulative Foreign Currency Exchange
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total equity, beginning balance	(150)	(116)
Other comprehensive income (loss) before reclassifications	114	(34)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive income (loss)	114	(34)
Total equity, ending balance	(36)	(150)	(116)
Net Unrealized Holding Gains on Investments, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total equity, beginning balance	0	(5)
Other comprehensive income (loss) before reclassifications	0	57
Amounts reclassified from accumulated other comprehensive income (loss)	0	(52)
Other comprehensive income (loss)	0	5
Total equity, ending balance	$ 0	$ 0	$ (5)

Accumulated Other Comprehensive Income (Loss) Reclassifications in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income, net	$ 7	$ 56	$ 38
Provision for (benefit from) income taxes, investments	258	(138)	(298)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassifications for the period	(2)	51	1
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of pension and other post-retirement items	(2)	(2)	(3)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassifications for the period	(2)	(1)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of pension and other post-retirement items	(2)	(2)	(3)
Benefit from income taxes	0	1	1
Total reclassifications for the period	(2)	(1)	(2)
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income, net	0	54	4
Provision for (benefit from) income taxes, investments	0	(2)	(1)
Income (Loss) from Continuing Operations, including portion attributable to noncontrolling interest	$ 0	$ 52	$ 3

Employee Benefits (Narrative Defined Contribution Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Domestic Plan [Member]
Defined Contribution Plan [Line Items]
Maximum employee contribution as a percentage of annual compensation	100.00%
Employer contributions to plans	$ 23	$ 11	$ 8
Foreign Plan [Member]
Defined Contribution Plan [Line Items]
Employer Contributions to Plan	$ 5	2	2
Defined Contribution Retirement Plan [Member] \| Domestic Plan [Member]
Defined Contribution Plan [Line Items]
Number of subsidiaries company provides a defined contribution plan	1
Length of service required to be eligible for annual retirement contributions (in years)	1 year
Employer Contributions to Plan	$ 29	$ 17	$ 12

Employee Benefits (Narrative Defined Benefit Plans) (Details) - Domestic Plan [Member] $ in Millions	1 Months Ended
	Dec. 31, 2014 plan	Dec. 31, 2017 USD ($)
Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of defined benefit plans amended \| plan	1
Pension Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions in the next fiscal year \| $		$ 3

Employee Benefits (Schedule Of Change In Benefit Obligation and Change In Plan Assets) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) subsidiary	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number Of Subsidiaries Company Provides Post Retirement Healthcare Benefit \| subsidiary	2
Domestic Plan [Member]
Change in plan assets
Fair value of plan assets, beginning of year	$ 614
Fair value of plan assets, end of year	650	$ 614
Foreign Plan [Member]
Change in plan assets
Fair value of plan assets, beginning of year	16
Fair value of plan assets, end of year	18	16
Defined Benefit Plans [Member] \| Domestic Plan [Member]
Change in benefit obligation
Benefit obligation, beginning of year	799	62
Benefit obligation assumed with acquisition	0	818
Service cost	3	1
Interest Cost	25	9
Actuarial loss (gain)	41	(74)
Benefits paid	(45)	(17)
Settlements	(16)	0
Foreign exchange effects	0	0
Benefit obligation, end of year	807	799
Change in plan assets
Fair value of plan assets, beginning of year	614	51
Acquisition	0	576
Actual return	97	7
Employer contribution	2	0
Benefits paid	(45)	(17)
Administrative expenses paid	(2)	(3)
Settlements	(16)	0
Foreign exchange effects	0	0
Fair value of plan assets, end of year	650	614
Funded status, end of year	(157)	(185)
Defined Benefit Plans [Member] \| Foreign Plan [Member]
Change in benefit obligation
Benefit obligation, beginning of year	125	95
Benefit obligation assumed with acquisition	0	21
Service cost	2	1
Interest Cost	3	2
Actuarial loss (gain)	0	13
Benefits paid	(3)	(3)
Settlements	(1)	0
Foreign exchange effects	16	(4)
Benefit obligation, end of year	142	125
Change in plan assets
Fair value of plan assets, beginning of year	16	0
Acquisition	0	16
Actual return	1	0
Employer contribution	1	3
Benefits paid	0	(3)
Administrative expenses paid	0	0
Settlements	(1)	0
Foreign exchange effects	1	0
Fair value of plan assets, end of year	18	16
Funded status, end of year	(124)	(109)
Other Postretirement Plan Benefits [Member] \| Domestic Plan [Member]
Change in benefit obligation
Benefit obligation, beginning of year	80	18
Benefit obligation assumed with acquisition	0	69
Service cost	1	0
Interest Cost	2	1
Actuarial loss (gain)	(1)	(6)
Benefits paid	(9)	(2)
Benefit obligation, end of year	73	80
Change in plan assets
Fair value of plan assets, beginning of year	0	0
Employer contribution	9	2
Plan participants' contributions	0	0
Benefits paid	(9)	(2)
Fair value of plan assets, end of year	0	0
Funded status, end of year	(73)	(80)
Other Postretirement Plan Benefits [Member] \| Foreign Plan [Member]
Change in benefit obligation
Benefit obligation, beginning of year	3	0
Benefit obligation assumed with acquisition	0	3
Service cost	0	0
Interest Cost	0	0
Actuarial loss (gain)	0	0
Benefits paid	0	0
Benefit obligation, end of year	3	3
Change in plan assets
Fair value of plan assets, beginning of year	0	0
Employer contribution	0	0
Plan participants' contributions	0	0
Benefits paid	0	0
Fair value of plan assets, end of year	0	0
Funded status, end of year	$ (3)	$ (3)

Employee Benefits (Schedule Of Amounts Recognized In The Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Noncurrent liabilities	$ (344)	$ (365)
Defined Benefit Plans [Member] \| Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	(2)	(2)
Noncurrent liabilities	(155)	(183)
Net amount recognized	(157)	(185)
Defined Benefit Plans [Member] \| Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	(3)	(2)
Noncurrent liabilities	(121)	(107)
Net amount recognized	(124)	(109)
Other Postretirement Plan Benefits [Member] \| Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	(8)	(8)
Noncurrent liabilities	(65)	(72)
Net amount recognized	(73)	(80)
Other Postretirement Plan Benefits [Member] \| Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	0	0
Noncurrent liabilities	(3)	(3)
Net amount recognized	$ (3)	$ (3)

Employee Benefits (Schedule Of Amounts Recognized In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans [Member] \| Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	$ (71)	$ (53)
Total before tax	(71)	(53)
Defined Benefit Plans [Member] \| Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	9	8
Total before tax	9	8
Pension Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive income (loss), benefits, net of tax	(43)	(30)
Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive income (loss), benefits, net of tax	0	(1)
Other Postretirement Plan Benefits [Member] \| Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	(5)	(4)
Total before tax	(5)	(4)
Other Postretirement Plan Benefits [Member] \| Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	0	0
Total before tax	$ 0	$ 0

Employee Benefits (Schedule Of Accumulated Benefit Obligations In Excess Of Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 650	$ 614
Domestic Plan [Member] \| Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0	$ 0
Domestic Plan [Member] \| Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	650	614	51
Domestic Plan [Member] \| Defined Benefit Plans [Member] \| Underfunded Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	(807)	(799)
Accumulated benefit obligation	(807)	(799)
Fair value of plan assets	650	614
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	16
Foreign Plan [Member] \| Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0	0
Foreign Plan [Member] \| Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	16	$ 0
Foreign Plan [Member] \| Defined Benefit Plans [Member] \| Underfunded Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	(128)	(113)
Accumulated benefit obligation	(126)	(110)
Fair value of plan assets	$ 5	$ 5
Minimum [Member] \| Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status, Percentage	80.00%

Employee Benefits (Schedule Of Net Benefit Costs, Other Changes in Plan Assets and Benefit Obligation Recognized In Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Amortization of net loss	$ (2)	$ (1)	$ (3)
Defined Benefit Plan, Expected Prior Service Cost (Credit), Next Fiscal Year	0
Defined Benefit Plan, Expected Gain (Loss), Next Fiscal Year	1
Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Prior Service Cost (Credit), Next Fiscal Year	0
Domestic Plan [Member] \| Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	1	0
Administrative expenses	2	3	0
Interest cost	25	9	2
Expected return on plan assets	(40)	(15)	(3)
Net amortization	1	1	1
Settlement benefits	0	0	1
Net periodic benefit cost (gain)	(9)	(1)	1
Net loss (gain) emerging	(18)	(67)	1
Amortization of net loss	(1)	(1)	(2)
Total recognized in OCI	(19)	(68)	(1)
Total net periodic benefit cost and OCI	(28)	(69)	0
Domestic Plan [Member] \| Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	0
Interest cost	2	1	1
Net amortization	0	0	0
Net periodic benefit cost (gain)	3	1	1
Net loss (gain) emerging	(1)	(6)	(2)
Total recognized in OCI	(1)	(6)	(2)
Total net periodic benefit cost and OCI	2	(5)	(1)
Foreign Plan [Member] \| Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	2
Administrative expenses	0	0	0
Interest cost	2	2	2
Expected return on plan assets	(1)	0	0
Net amortization	1	0	1
Settlement benefits	0	0	0
Net periodic benefit cost (gain)	4	4	5
Net loss (gain) emerging	0	13	(17)
Amortization of net loss	(1)	0	(1)
Total recognized in OCI	(1)	13	(18)
Total net periodic benefit cost and OCI	3	17	$ (13)
Foreign Plan [Member] \| Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	0	0
Net amortization	0	0
Net periodic benefit cost (gain)	0	0
Net loss (gain) emerging	0	0
Total recognized in OCI	0	0
Total net periodic benefit cost and OCI	$ 0	$ 0

Employee Benefits (Schedule Of Weighted Average Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Domestic Plan [Member] \| Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.40%	3.80%	4.00%
Rate of compensation increase	0.00%	0.00%	0.00%
Discount rate for benefit obligations	3.80%	3.20%	3.50%
Discount rate for service cost	4.10%	3.40%	0.00%
Discount rate for interest cost	3.20%	2.90%	0.00%
Expected return on plan assets	6.80%	6.80%	7.00%
Rate of compensation increase		0.00%	0.00%
Domestic Plan [Member] \| Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.00%	3.30%	3.50%
Health care cost trend rate - Initial rate	7.30%	7.30%	0.00%
Health care cost trend rate- Ultimate rate (periodic benefit costs)	4.60%	4.50%	0.00%
Health care cost trend rate- Ultimate rate (benefit obligation)	4.50%	4.50%	0.00%
Health care cost trend rate- Years to ultimate (benefit obligations)	11 years	11 years	0 years
Discount rate for benefit obligations	3.30%	2.60%	3.30%
Discount rate for service cost	3.80%	3.10%	0.00%
Discount rate for interest cost	2.60%	2.80%	0.00%
Health care cost trend rate- Initial rate (periodic benefit costs)	6.80%	7.00%	0.00%
Health care cost trend rate- Years to ultimate (periodic benefit costs)	11 years	12 years	0 years
Foreign Plan [Member] \| Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	1.80%	1.80%	2.40%
Rate of compensation increase	2.60%	2.60%	2.50%
Discount rate for benefit obligations	1.80%	2.40%	1.90%
Discount rate for service cost	1.90%	2.40%	0.00%
Discount rate for interest cost	2.00%	2.40%	0.00%
Expected return on plan assets	3.80%	4.60%	0.00%
Rate of compensation increase	2.60%	2.60%	2.50%
Foreign Plan [Member] \| Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.00%	4.00%
Health care cost trend rate - Initial rate	6.20%	6.20%
Health care cost trend rate- Ultimate rate (periodic benefit costs)	4.50%	4.50%
Health care cost trend rate- Ultimate rate (benefit obligation)	4.50%	4.50%
Health care cost trend rate- Years to ultimate (benefit obligations)	12 years	12 years
Discount rate for benefit obligations	3.30%	3.30%
Discount rate for service cost	3.30%	3.30%
Discount rate for interest cost	3.30%	3.30%
Health care cost trend rate- Initial rate (periodic benefit costs)	6.80%	6.80%
Health care cost trend rate- Years to ultimate (periodic benefit costs)	12 years	13 years

Employee Benefits (Multiemployer Plans) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) plan	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Multiemployer Plans [Line Items]
Number of multiemployer plans \| plan	2
Foreign Plan [Member]
Multiemployer Plans [Line Items]
Contributions to multi-employer plans \| $	$ 8	$ 5	$ 4

Employee Benefits (Schedule Of Estimated Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Pension Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Year 1	$ 51
Year 2	53
Year 3	52
Year 4	52
Year 5	53
Years 6 to 10	265
Other Postretirement Plan Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Year 1	8
Year 2	8
Year 3	8
Year 4	8
Year 5	8
Years 6 to 10	$ 30

Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense on equity awards	$ 14	$ 14	$ 10
Total intrinsic value of options exercised	24	4	1
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	8	1	0
Transaction and integration-related costs	$ 29	104	0
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards, term (in years)	10 years
Unrecognized compensation expense	$ 4
Unrecognized compensation expense, weighted-average period of recognition (in years)	1 year 4 months 24 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 0
Total fair value of shares of restricted stock that vested	0	4	8
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 17
Unrecognized compensation expense, weighted-average period of recognition (in years)	1 year 7 months 6 days
Total fair value of shares of restricted stock that vested	$ 6	4	$ 1
Ratably On Annual Basis [Member] \| Stock Options [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period	1 year
Ratably On Annual Basis [Member] \| Stock Options [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period	4 years
Ratably On Annual Basis [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period	3 years
Cliff Vest [Member] \| Restricted Stock Units (RSUs) [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period	1 year
Cliff Vest [Member] \| Restricted Stock Units (RSUs) [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period	6 years
First One Half Increment On Anniversary Of Award Date [Member] \| Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period	5 years
Second One Half Increment On Anniversary Of Award Date [Member] \| Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period	9 years 6 months
Axiall Corporation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price (in dollars per share)				$ 33.00
Axiall Corporation [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense on equity awards	$ 9	38
Unrecognized compensation expense	$ 5
Unrecognized compensation expense, weighted-average period of recognition (in years)	9 months 18 days
Total fair value of shares of restricted stock that vested	$ 11	3
Transaction and integration-related costs		$ 33
Total fair value of shares of restricted stock that were cancelled	$ 2

Stock-Based Compensation (Schedule Of Option Activity And Changes) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Options
Options, Outstanding, beginning balance \| shares	1,404,734
Options, Granted \| shares	289,553
Options, Exercised \| shares	(401,505)
Options, Cancelled \| shares	(23,181)
Options, Outstanding, ending balance \| shares	1,269,601
Options, Exercisable, ending balance \| shares	719,676
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding, beginning balance (in dollars per share) \| $ / shares	$ 33.76
Weighted Average Exercise Price, Granted (in dollars per share) \| $ / shares	61.87
Weighted Average Exercise Price, Exercised (in dollars per share) \| $ / shares	29.68
Weighted Average Exercise Price, Cancelled (in dollars per share) \| $ / shares	56.92
Weighted Average Exercise Price, Outstanding, ending balance (in dollars per share) \| $ / shares	41.04
Weighted Average Exercise Price, Exercisable, ending balance (in dollars per share) \| $ / shares	$ 28.89
Weighted Average Remaining Term (Years), Outstanding	5 years 10 months 24 days
Weighted Average Remaining Term (Years), Exercisable	3 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding \| $	$ 83
Aggregate Intrinsic Value, Exercisable \| $	$ 56

Stock-Based Compensation (Schedule Of Range Of Exercise Prices For Outstanding Options) (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
$7.12 - $9.65 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise prices, minimum (in dollars per share)	$ 7.12
Range of exercise prices, maximum (in dollars per share)	$ 9.65
Options Outstanding \| shares	300,366
Weighted Average Remaining Contractual Life (Years)	1 year 7 months 6 days
$10.26 - $18.05 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise prices, minimum (in dollars per share)	$ 10.26
Range of exercise prices, maximum (in dollars per share)	$ 18.05
Options Outstanding \| shares	167,582
Weighted Average Remaining Contractual Life (Years)	3 years 7 months 6 days
$22.92 - $30.05 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise prices, minimum (in dollars per share)	$ 22.92
Range of exercise prices, maximum (in dollars per share)	$ 30.05
Options Outstanding \| shares	316,601
Weighted Average Remaining Contractual Life (Years)	7 years 7 months 6 days
$40.38 - $52.35 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise prices, minimum (in dollars per share)	$ 40.38
Range of exercise prices, maximum (in dollars per share)	$ 52.35
Options Outstanding \| shares	285,553
Weighted Average Remaining Contractual Life (Years)	9 years 1 month 6 days
$61.87 - $68.18 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise prices, minimum (in dollars per share)	$ 61.87
Range of exercise prices, maximum (in dollars per share)	$ 68.18
Options Outstanding \| shares	199,499
Weighted Average Remaining Contractual Life (Years)	6 years 9 months 18 days

Stock-Based Compensation (Schedule Of Weighted Average Value And Assumptions For Fair Value Of Options) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value (in dollars per share)	$ 15.84	$ 11.67	$ 20.21
Risk-free interest rate	2.10%	1.40%	1.70%
Expected life in years	5 years	5 years	5 years
Expected volatility	29.20%	32.90%	34.20%
Expected dividend yield	1.20%	1.60%	0.90%
Restricted Stock [Member] \| Axiall Corporation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average vesting period (in years)	9 months 18 days
Risk-free interest rate	1.60%
Expected volatility	23.10%
Expected dividend yield	0.80%

Stock-Based Compensation (Schedule Of Non-Vested Restricted Stock Award and RSU Activity and Changes) (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Restricted Stock [Member] \| Axiall Corporation [Member]
Number of Shares
Number of Shares, Non-vested, beginning balance \| shares	286,147
Number of Shares, Vested \| shares	(161,324)
Number of Shares, Forfeited \| shares	(23,831)
Number of Shares, Non-vested, ending balance \| shares	100,992
Weighted Average Grant Date Fair Value
Weighted Average Fair Value, Non-vested, beginning balance (in dollars per share) \| $ / shares	$ 60.77
Weighted Average Fair Value, Vested (in dollars per share) \| $ / shares	65.29
Weighted Average Fair Value, Forfeited (in dollars per share) \| $ / shares	66.97
Weighted Average Fair Value, Non-vested, ending balance (in dollars per share) \| $ / shares	$ 106.53
Restricted Stock Units (RSUs) [Member]
Number of Shares
Number of Shares, Non-vested, beginning balance \| shares	597,559
Number of Shares, Granted \| shares	198,659
Number of Shares, Vested \| shares	(91,997)
Number of Shares, Forfeited \| shares	(40,355)
Number of Shares, Non-vested, ending balance \| shares	663,866
Weighted Average Grant Date Fair Value
Weighted Average Fair Value, Non-vested, beginning balance (in dollars per share) \| $ / shares	$ 55.64
Weighted Average Fair Value, Granted (in dollars per share) \| $ / shares	62.46
Weighted Average Fair Value, Vested (in dollars per share) \| $ / shares	61.39
Weighted Average Fair Value, Forfeited (in dollars per share) \| $ / shares	56.08
Weighted Average Fair Value, Non-vested, ending balance (in dollars per share) \| $ / shares	$ 56.86

Income Taxes (Narrative) (Details) $ in Millions	3 Months Ended	12 Months Ended
Income Taxes (Narrative) (Details) $ in Millions	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Income Tax Disclosure [Abstract]
Provisional adjustment of income tax benefit		$ 591
Foreign and state net operating loss carryforwards	$ 405	405
Change in valuation allowance		3
Provisional tax expense related to one-time repatriation	$ 5
Foreign tax		$ 7

Income Taxes (Components Of Income (Loss) Before Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 917	$ 476	$ 880
Foreign	164	82	83
Income before income taxes	$ 1,081	$ 558	$ 963

Income Taxes (Schedule Of The Provision For (Benefit From) Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal	$ 231	$ 8	$ 225
State	18	9	24
Foreign	27	20	9
Total Current	276	37	258
Deferred
Federal	(557)	136	30
State	25	(33)	3
Foreign	(2)	(2)	7
Total Deferred	(534)	101	40
Provision for (benefit from) income taxes	$ (258)	$ 138	$ 298

Income Taxes (Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Provision for federal income tax, at statutory rate	$ 378	$ 195	$ 337
State income tax provision, net of federal income tax effect	26	1	17
Foreign income tax rate differential	(33)	(8)	(13)
Manufacturing deduction	(23)	(2)	(24)
Depletion	(7)	(2)	0
Noncontrolling interests	(9)	(7)	(7)
Tax on previously held shares of Axiall Corporation and certain other acquisition related items	0	(13)	0
Tax Act related adjustment	(591)	0	0
Changes in state apportionment and other state adjustments	2	(17)	0
Research and development expenditures and adjustments related to prior years' tax returns	(1)	(8)	0
Other, net	0	(1)	(12)
Provision for (benefit from) income taxes	$ (258)	$ 138	$ 298

Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforward	$ 64	$ 70
Credit carryforward	26	24
Accruals	53	67
Pension	79	114
Allowance for doubtful accounts	5	12
Inventories	11	13
Other	15	36
Deferred taxes assets—total	253	336
Property, plant and equipment	(906)	(1,374)
Intangibles	(154)	(221)
Turnaround costs	(8)	(1)
Basis difference—consolidated partnerships	(209)	(308)
Other	(18)	(17)
Deferred tax liabilities—total	(1,295)	(1,921)
Valuation allowance	(56)	(53)
Total net deferred tax liabilities	(1,098)	(1,638)
Balance sheet classifications
Noncurrent deferred tax asset	13	12
Noncurrent deferred tax liability	$ (1,111)	$ (1,650)

Earnings per Share (Narrative) (Details) - shares	12 Months Ended
Earnings per Share (Narrative) (Details) - shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Options excluded from computation of earnings per share, shares	0	318,259	301,969

Earnings per Share (Schedule Of Net Income Attributable To Common Stockholders) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 802	$ 211	$ 153	$ 138	$ 99	$ 66	$ 111	$ 123	$ 1,304	$ 399	$ 646
Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted									(7)	(2)	(3)
Net income attributable to common shareholders									$ 1,297	$ 397	$ 643

Earnings per Share (Reconciliation Of Denominator For Basic And Diluted Earnings (Loss) Per Share) (Details) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Weighted average common shares—basic									129,087,043	129,367,712	131,823,707
Plus incremental shares from: Assumed exercise of options									452,970	607,110	478,105
Weighted average common shares—diluted									129,540,013	129,974,822	132,301,812
Basic (in dollars per share)	$ 6.18	$ 1.62	$ 1.18	$ 1.07	$ 0.76	$ 0.51	$ 0.85	$ 0.94	$ 10.05	$ 3.07	$ 4.88
Diluted (in dollars per share)	$ 6.15	$ 1.61	$ 1.17	$ 1.06	$ 0.76	$ 0.51	$ 0.85	$ 0.94	$ 10.00	$ 3.06	$ 4.86

Supplemental Information (Details) - USD ($) $ in Millions	12 Months Ended
Supplemental Information (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combination Bargain Purchase Gain Net Of Related Expenses			$ 21
Accrued Liabilities
Accrued liabilities	$ 657	$ 538
Accrued rebates	108	78
Accrued Income Taxes, Current	130	11
Non-Cash Investing Activity [Abstract]
Increase (Decrease) in Capital Expenditure Accrual	(9)	7	(7)
Cash Flow Information
Interest paid, net of interest capitalized	154	46	32
Income taxes paid	$ 84	3	$ 314
Axiall Corporation [Member]
Non-Cash Investing Activity [Abstract]
Remeasurement gain (loss)		$ (49)

Related Party And Affiliate Transactions (Details) $ in Millions, T in Billions		4 Months Ended	12 Months Ended
	Jun. 17, 2015 USD ($) T	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Ownership interest (in percent)			100.00%
Related party receivable		$ 8	$ 9	$ 8
Dividends received from equity method investments			6	5	$ 6
Affiliates [Member]
Related Party Transaction [Line Items]
Incurred and paid lease payments			3	3	2
Pipeline Fees For Transport Of Natural Gas Liquid Feedstocks [Member] \| Cypress Interstate Pipeline L.L.C [Member] \| Corporate Joint Venture [Member]
Related Party Transaction [Line Items]
Purchases from related parties			15	14	14
Accounts payable due to affiliate		1	$ 1	1
Cypress Interstate Pipeline L.L.C [Member] \| Corporate Joint Venture [Member]
Related Party Transaction [Line Items]
Ownership interest (in percent)			50.00%
Investments in joint ventures		9	$ 9	9
EPS Ethylene Pipeline Süd GmbH & Co. KG [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Ownership percentage by parent			10.00%
EPS Ethylene Pipeline Süd GmbH & Co. KG [Member] \| Pipeline Fees For Transport Of Ethylene Feedstocks [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Purchases from related parties			$ 0	1	1
Accounts payable due to affiliate		0	$ 0	0
InfraServ Knapsack GmbH & Co. KG [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Ownership percentage by parent			15.00%
InfraServ Gendorf GmbH & Co. KG [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Ownership percentage by parent			11.00%
InfraServ Knapsack & Gendorf GmbH & Co. KG [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Investments in joint ventures		50	$ 56	50
InfraServ Knapsack & Gendorf GmbH & Co. KG [Member] \| Electricity And Technical Services [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Purchases from related parties			133	131	116
Accounts payable due to affiliate		25	$ 33	25
Shriram Axiall Private Limited [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Ownership interest (in percent)			50.00%
Investments in joint ventures		2	$ 0	2
RS Cogen LLC [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Investments in joint ventures		10	10	10
Purchases from related parties		9	26
Accounts payable due to affiliate		1	$ 2	1
RS Cogen LLC [Member] \| Corporate Joint Venture [Member]
Related Party Transaction [Line Items]
Ownership interest (in percent)			50.00%
Vinyl Solutions, LLC [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Ownership interest (in percent)			50.00%
Sales to related parties		6	$ 17
Related party receivable		5	7	5
LACC [Member] \| Affiliates [Member]
Related Party Transaction [Line Items]
Ownership interest (in percent)	10.00%
Investments in joint ventures		59	125	59
Related party receivable		1	0	1
Plant capacity (in T) \| T	1
Maximum Capital Commitment	$ 225
Optional ownership percentage	50.00%
Funding to related parties		17	66
American Air Liquide Holdings [Member] \| American Air Liquide Holdings, Inc. [Member]
Related Party Transaction [Line Items]
Sales to related parties			7	4
Related party receivable		1	1	1
Accounts payable due to related parties		$ 4	2	4
Purchases and lease expense to related parties			$ 30	$ 22	$ 10

Westlake Chemical Partners LP (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Sep. 29, 2017	Apr. 29, 2015	Aug. 04, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Partners' Capital Account, Units, Sold in Public Offering	5,175,000		12,937,500
Sale of Unit Price Per Unit	$ 22.00		$ 24.00
Net proceeds from WLKP LP common stock units	$ 111		$ 286	$ 111	$ 0	$ 0
Payments of Stock Issuance Costs	$ 3		$ 24
Westlake Chemical OpCo LP [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited Partnership Ownership Percentage Increase	5.00%	2.70%
Subsidiary of Common Parent [Member] \| Westlake Chemical Partners LP [Member] \| IPO [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited partner interest (percent)			47.80%
Subsidiary of Common Parent [Member] \| Westlake Chemical OpCo LP [Member] \| IPO [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	18.30%		10.60%
Limited partner interest (percent)	81.70%		89.40%	81.70%

Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Environmental contingency accrual		$ 49	$ 49
Minimum [Member]
Loss Contingencies [Line Items]
Reasonably possible additional loss - Environmental		55
Maximum [Member]
Loss Contingencies [Line Items]
Reasonably possible additional loss - Environmental		110
PolyOne [Member] \| Pending Litigation [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 17
Gain Contingency, Unrecorded Amount	$ 6
Environmental Protection Agency [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Environmental Remediation Expense Estimated		200
Environmental Protection Agency [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Environmental Remediation Expense Estimated		250
Environmental Protection Agency [Member] \| Operation and Maintenance [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost		1
Environmental Protection Agency [Member] \| Operation and Maintenance [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost		$ 3

Commitments And Contingencies (Future Minimum Lease Commitments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense	$ 147	$ 87	$ 69
Operating Leases
2018	108
2019	97
2020	73
2021	56
2022	44
Thereafter	651
Total minimum lease payments	1,029
Capital Leases
2018	3
2019	3
2020	3
2021	2
2022	2
Thereafter	9
Total minimum lease payments	22
Less: Imputed interest costs	(12)
Present value of net minimum lease payments	$ 10

Commitments And Contingencies (Minimum Purchase Obligations) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Unconditional purchase obligations
2018	$ 430
2019	412
2020	376
2021	330
2022	$ 95

Segment And Geographic Information (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 plant Segment customer	Dec. 31, 2016 customer	Dec. 31, 2015 customer
Segment Reporting Information [Line Items]
Number of segments \| Segment	2
Number of Building Product Facilities \| plant	24
Olefins [Member]
Segment Reporting Information [Line Items]
Number of major customers	0	0	0
Vinyls [Member]
Segment Reporting Information [Line Items]
Number of major customers	0	0	0

Segment And Geographic Information (Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 2,010	$ 2,109	$ 1,979	$ 1,943	$ 1,735	$ 1,280	$ 1,086	$ 975	$ 8,041	$ 5,076	$ 4,463
Income from operations	$ 365	$ 366	$ 266	$ 236	$ 153	$ 46	$ 180	$ 202	1,233	581	960
Depreciation and amortization									601	378	246
Other income, net									7	56	38
Provision for (benefit from) income taxes									(258)	138	298
Payments to Acquire Property, Plant, and Equipment									577	629	491
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales									8,041	5,076	4,463
Operating Segments [Member] \| Olefins [Member]
Segment Reporting Information [Line Items]
Net sales									2,051	1,894	2,260
Income from operations									655	558	747
Depreciation and amortization									145	136	111
Other income, net									3	5	5
Provision for (benefit from) income taxes									63	175	243
Payments to Acquire Property, Plant, and Equipment									97	324	305
Operating Segments [Member] \| Olefins [Member] \| Polyethylene [Member]
Segment Reporting Information [Line Items]
Net sales									1,518	1,463	1,651
Operating Segments [Member] \| Olefins [Member] \| Styrene, Feedstock And Other [Member]
Segment Reporting Information [Line Items]
Net sales									533	431	609
Operating Segments [Member] \| Vinyls [Member]
Segment Reporting Information [Line Items]
Net sales									5,990	3,182	2,203
Income from operations									647	174	255
Depreciation and amortization									449	238	134
Other income, net									(1)	3	8
Provision for (benefit from) income taxes									(302)	25	64
Payments to Acquire Property, Plant, and Equipment									459	302	176
Operating Segments [Member] \| Vinyls [Member] \| PVC, Caustic Soda And Other [Member]
Segment Reporting Information [Line Items]
Net sales									4,769	2,493	1,718
Operating Segments [Member] \| Vinyls [Member] \| Building Products [Member]
Segment Reporting Information [Line Items]
Net sales									1,221	689	485
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Income from operations									(69)	(151)	(42)
Depreciation and amortization									7	4	1
Other income, net									5	48	25
Provision for (benefit from) income taxes									(19)	(62)	(9)
Payments to Acquire Property, Plant, and Equipment									21	3	10
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales									394	191	108
Intersegment Eliminations [Member] \| Olefins [Member]
Segment Reporting Information [Line Items]
Net sales									393	165	107
Intersegment Eliminations [Member] \| Vinyls [Member]
Segment Reporting Information [Line Items]
Net sales									$ 1	$ 26	$ 1

Segment And Geographic Information (Total Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total assets	$ 12,076	$ 10,890
Operating Segments [Member] \| Olefins [Member]
Segment Reporting Information [Line Items]
Total assets	2,006	2,093
Operating Segments [Member] \| Vinyls [Member]
Segment Reporting Information [Line Items]
Total assets	8,853	8,287
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 1,217	$ 510

Segment And Geographic Information (Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Income from operations for reportable segments	$ 365	$ 366	$ 266	$ 236	$ 153	$ 46	$ 180	$ 202	$ 1,233	$ 581	$ 960
Interest expense									(159)	(79)	(35)
Other income, net									7	56	38
Income before income taxes									$ 1,081	$ 558	$ 963

Segment And Geographic Information (Geographic Information for Sales to External Customers and Long-lived Assets) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 2,010	$ 2,109	$ 1,979	$ 1,943	$ 1,735	$ 1,280	$ 1,086	$ 975	$ 8,041	$ 5,076	$ 4,463
Long-lived assets	6,412				6,420				6,412	6,420
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									5,739	3,526	3,133
Long-lived assets	5,668				5,783				5,668	5,783
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									432	402	394
Long-lived assets	504				401				504	401
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									653	317	196
Switzerland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									142	101	107
BRAZIL
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									108	41	16
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									104	87	46
Italy [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									96	84	90
TAIWAN, PROVINCE OF CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									96	25	0
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									671	493	$ 481
Long-lived assets	$ 240				$ 236				$ 240	$ 236

Guarantor Disclosures (Narrative) (Details) $ in Millions	12 Months Ended
Guarantor Disclosures (Narrative) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Condensed Financial Statements, Captions [Line Items]
Ownership interest (in percent)	100.00%
Senior Notes [Member] \| 4.375% Senior Notes Due 2047 [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	4.375%
Debt instrument maturity	2047
Senior Notes [Member] \| 3.60% Senior Notes Due 2022 [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	3.60%
Debt instrument maturity	2022
Senior Notes [Member] \| 3.60% Senior Notes Due 2026 [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	3.60%
Debt instrument maturity	2026
Senior Notes [Member] \| 5.0% 2046 [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	5.00%
Debt instrument maturity	2046
Senior Notes [Member] \| 4.875% Westlake Senior 2023 Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	4.875%
Debt instrument maturity	2023
3.60%, 5.0%, 4.625%, 4.875% Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Senior notes, minimum debt amount guaranteed by subsidiaries	$ 5

Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 1,531	$ 459	$ 663	$ 881
Accounts receivable, net	1,001	939
Inventories	900	801
Prepaid expenses and other current assets	30	48
Restricted cash	1	161
Total current assets	3,463	2,408
Property, plant and equipment, net	6,412	6,420
Goodwill	1,012	947	62
Customer relationships, net	616	611
Other intangible assets, net	161	176
Other assets, net	412	328
Total assets	12,076	10,890
Accounts payable	600	496
Accrued liabilities	657	538
Current portion of long-term debt, net	710	0
Term loan	0	149
Total current liabilities	1,967	1,183
Long-term debt, net	3,127	3,679
Deferred income taxes	1,111	1,650
Pension and other liabilities	502	486
Total liabilities	6,707	6,998
Total Westlake Chemical Corporation stockholders' equity	4,874	3,524
Noncontrolling interests	495	368
Total equity	5,369	3,892	3,562	3,202
Total liabilities and equity	12,076	10,890
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	(7,038)	(4,833)
Inventories	0	0
Prepaid expenses and other current assets	(79)	(37)
Restricted cash	0	0
Total current assets	(7,117)	(4,870)
Property, plant and equipment, net	0	0
Goodwill	0	0
Customer relationships, net	0	0
Other intangible assets, net	0	(25)
Other assets, net	(12,363)	(10,832)
Total assets	(19,480)	(15,727)
Accounts payable	(6,855)	(4,808)
Accrued liabilities	(262)	(61)
Current portion of long-term debt, net	0
Term loan		0
Total current liabilities	(7,117)	(4,869)
Long-term debt, net	(4,369)	(3,997)
Deferred income taxes	(7)	(23)
Pension and other liabilities	0	0
Total liabilities	(11,493)	(8,889)
Total Westlake Chemical Corporation stockholders' equity	(7,987)	(6,838)
Noncontrolling interests	0	0
Total equity	(7,987)	(6,838)
Total liabilities and equity	(19,480)	(15,727)
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	1,089	147	303	656
Accounts receivable, net	3,331	2,118
Inventories	0	0
Prepaid expenses and other current assets	52	31
Restricted cash	0	0
Total current assets	4,472	2,296
Property, plant and equipment, net	0	0
Goodwill	0	0
Customer relationships, net	0	0
Other intangible assets, net	0	0
Other assets, net	10,706	9,170
Total assets	15,178	11,466
Accounts payable	6,367	4,331
Accrued liabilities	189	26
Current portion of long-term debt, net	710
Term loan		0
Total current liabilities	7,266	4,357
Long-term debt, net	3,034	3,585
Deferred income taxes	0	0
Pension and other liabilities	4	0
Total liabilities	10,304	7,942
Total Westlake Chemical Corporation stockholders' equity	4,874	3,524
Noncontrolling interests	0	0
Total equity	4,874	3,524
Total liabilities and equity	15,178	11,466
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	57	53	7	3
Accounts receivable, net	4,128	3,330
Inventories	654	598
Prepaid expenses and other current assets	26	42
Restricted cash	1	0
Total current assets	4,866	4,023
Property, plant and equipment, net	4,374	4,476
Goodwill	855	792
Customer relationships, net	479	468
Other intangible assets, net	88	131
Other assets, net	798	874
Total assets	11,460	10,764
Accounts payable	864	748
Accrued liabilities	484	390
Current portion of long-term debt, net	0
Term loan		0
Total current liabilities	1,348	1,138
Long-term debt, net	4,242	4,091
Deferred income taxes	1,026	1,581
Pension and other liabilities	347	361
Total liabilities	6,963	7,171
Total Westlake Chemical Corporation stockholders' equity	4,497	3,593
Noncontrolling interests	0	0
Total equity	4,497	3,593
Total liabilities and equity	11,460	10,764
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	385	259	$ 353	$ 222
Accounts receivable, net	580	324
Inventories	246	203
Prepaid expenses and other current assets	31	12
Restricted cash	0	161
Total current assets	1,242	959
Property, plant and equipment, net	2,038	1,944
Goodwill	157	155
Customer relationships, net	137	143
Other intangible assets, net	73	70
Other assets, net	1,271	1,116
Total assets	4,918	4,387
Accounts payable	224	225
Accrued liabilities	246	183
Current portion of long-term debt, net	0
Term loan		149
Total current liabilities	470	557
Long-term debt, net	220	0
Deferred income taxes	92	92
Pension and other liabilities	151	125
Total liabilities	933	774
Total Westlake Chemical Corporation stockholders' equity	3,490	3,245
Noncontrolling interests	495	368
Total equity	3,985	3,613
Total liabilities and equity	$ 4,918	$ 4,387

Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Operations) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 2,010	$ 2,109	$ 1,979	$ 1,943	$ 1,735	$ 1,280	$ 1,086	$ 975	$ 8,041	$ 5,076	$ 4,463
Cost of sales									6,272	4,095	3,278
Gross profit	498	498	405	368	282	203	241	255	1,769	981	1,185
Selling, general and administrative expenses									399	258	218
Amortization of intangibles									108	38	7
Transaction and integration-related costs									29	104	0
Income from operations	365	366	266	236	153	46	180	202	1,233	581	960
Interest expense									(159)	(79)	(35)
Other income (expense), net									7	56	38
Income before income taxes									1,081	558	963
Provision for (benefit from) income taxes									(258)	138	298
Equity in net income of subsidiaries									0	0	0
Net income	816	219	159	145	105	70	116	129	1,339	420	665
Net income attributable to noncontrolling interests									35	21	19
Net income attributable to Westlake Chemical Corporation	$ 802	$ 211	$ 153	$ 138	$ 99	$ 66	$ 111	$ 123	1,304	399	646
Comprehensive income attributable to Westlake Chemical Corporation									1,432	407	596
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									(1,752)	(1,379)	(1,381)
Cost of sales									(1,725)	(1,357)	(1,361)
Gross profit									(27)	(22)	(20)
Selling, general and administrative expenses									(27)	(22)	(20)
Amortization of intangibles									0	0	0
Transaction and integration-related costs									0	0
Income from operations									0	0	0
Interest expense									179	82	42
Other income (expense), net									(179)	(82)	(42)
Income before income taxes									0	0	0
Provision for (benefit from) income taxes									0	0	0
Equity in net income of subsidiaries									(1,318)	(400)	(664)
Net income									(1,318)	(400)	(664)
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to Westlake Chemical Corporation									(1,318)	(400)	(664)
Comprehensive income attributable to Westlake Chemical Corporation									(1,326)	(407)	(596)
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									0	0	0
Cost of sales									0	0	0
Gross profit									0	0	0
Selling, general and administrative expenses									3	2	3
Amortization of intangibles									1	1	0
Transaction and integration-related costs									0	0
Income from operations									(4)	(3)	(3)
Interest expense									(154)	(83)	(42)
Other income (expense), net									154	77	20
Income before income taxes									(4)	(9)	(25)
Provision for (benefit from) income taxes									10	(8)	(7)
Equity in net income of subsidiaries									1,318	400	664
Net income									1,304	399	646
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to Westlake Chemical Corporation									1,304	399	646
Comprehensive income attributable to Westlake Chemical Corporation									1,432	407	596
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									6,650	4,010	3,558
Cost of sales									5,559	3,533	2,842
Gross profit									1,091	477	716
Selling, general and administrative expenses									292	178	146
Amortization of intangibles									81	27	5
Transaction and integration-related costs									27	103
Income from operations									691	169	565
Interest expense									(178)	(76)	(35)
Other income (expense), net									(3)	(14)	5
Income before income taxes									510	79	535
Provision for (benefit from) income taxes									(312)	115	275
Equity in net income of subsidiaries									0	0	0
Net income									822	(36)	260
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to Westlake Chemical Corporation									822	(36)	260
Comprehensive income attributable to Westlake Chemical Corporation									833	11	261
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									3,143	2,445	2,286
Cost of sales									2,438	1,919	1,797
Gross profit									705	526	489
Selling, general and administrative expenses									131	100	89
Amortization of intangibles									26	10	2
Transaction and integration-related costs									2	1
Income from operations									546	415	398
Interest expense									(6)	(2)	0
Other income (expense), net									35	75	55
Income before income taxes									575	488	453
Provision for (benefit from) income taxes									44	31	30
Equity in net income of subsidiaries									0	0	0
Net income									531	457	423
Net income attributable to noncontrolling interests									35	21	19
Net income attributable to Westlake Chemical Corporation									496	436	404
Comprehensive income attributable to Westlake Chemical Corporation									$ 493	$ 396	$ 335

Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Cash Flows) (Details) - USD ($) $ in Millions			3 Months Ended								12 Months Ended
	Sep. 29, 2017	Aug. 04, 2014	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net income (loss)			$ 816	$ 219	$ 159	$ 145	$ 105	$ 70	$ 116	$ 129	$ 1,339	$ 420	$ 665
Depreciation and amortization											601	378	246
Deferred income taxes											(534)	101	40
Net changes in working capital and other											132	(65)	128
Net cash provided by operating activities											1,538	834	1,079
Acquisition of business, net of cash acquired											(13)	(2,438)	16
Additions to property, plant and equipment											(577)	(629)	(491)
Additions to cost method investment											(66)	(17)	0
Proceeds from disposition of equity method investment											0	0	28
Proceeds from sales and maturities of securities											0	663	49
Purchase of securities											0	(138)	(605)
Other											4	(4)	(3)
Net cash used for investing activities											(652)	(2,563)	(1,006)
Intercompany financing											0	0	0
Receivable under the investment management agreement											0
Debt issuance costs											(6)	(36)	0
Dividends paid											(103)	(97)	(92)
Distributions to noncontrolling interests											(28)	(17)	(15)
Proceeds from debt issuance and drawdown of revolver											233	608	53
Net proceeds from issuance of Westlake Partners common units	$ 111	$ 286									111	0	0
Proceeds from senior notes issuance											745	1,429	0
Repayment of term loan											(150)	0	0
Restricted cash associated with term loan											154	(154)	0
Repayment of notes payable											(257)	(13)	(74)
Repurchase of common stock for treasury											0	(67)	(163)
Repayment of revolver											(550)	(125)	0
Other											11	5	4
Net cash provided by (used for) financing activities											160	1,533	(287)
Effect of exchange rate changes on cash and cash equivalents											26	(8)	(4)
Net increase (decrease) in cash and cash equivalents											1,072	(204)	(218)
Cash and cash equivalents at beginning of the year						459				663	459	663	881
Cash and cash equivalents at end of the year			1,531				459				1,531	459	663
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)											(1,318)	(400)	(664)
Depreciation and amortization											0	0	0
Deferred income taxes											0	0	0
Net changes in working capital and other											1,318	400	664
Net cash provided by operating activities											0	0	0
Acquisition of business, net of cash acquired											0	0	0
Additions to property, plant and equipment											0	0	0
Additions to cost method investment											0	0
Proceeds from disposition of equity method investment													0
Proceeds from sales and maturities of securities												0	0
Purchase of securities												0	0
Other											136	0	0
Net cash used for investing activities											136	0	0
Intercompany financing											0	0	0
Receivable under the investment management agreement											(136)
Debt issuance costs											0	0
Dividends paid											0	0	0
Distributions to noncontrolling interests											0	0	0
Proceeds from debt issuance and drawdown of revolver											0	0	0
Net proceeds from issuance of Westlake Partners common units											0
Proceeds from senior notes issuance											0	0
Repayment of term loan											0
Restricted cash associated with term loan											0	0
Repayment of notes payable											0	0	0
Repurchase of common stock for treasury												0	0
Repayment of revolver											0	0
Other											0	0	0
Net cash provided by (used for) financing activities											(136)	0	0
Effect of exchange rate changes on cash and cash equivalents											0	0	0
Net increase (decrease) in cash and cash equivalents											0	0	0
Cash and cash equivalents at beginning of the year						0				0	0	0	0
Cash and cash equivalents at end of the year			0				0				0	0	0
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)											1,304	399	646
Depreciation and amortization											0	0	0
Deferred income taxes											12	1	0
Net changes in working capital and other											(1,327)	(437)	(659)
Net cash provided by operating activities											(11)	(37)	(13)
Acquisition of business, net of cash acquired											0	0	0
Additions to property, plant and equipment											0	0	0
Additions to cost method investment											0	0
Proceeds from disposition of equity method investment													0
Proceeds from sales and maturities of securities												658	49
Purchase of securities												(138)	(556)
Other											0	0	0
Net cash used for investing activities											0	520	(507)
Intercompany financing											746	(2,199)	418
Receivable under the investment management agreement											136
Debt issuance costs											(6)	(35)
Dividends paid											(103)	(97)	(92)
Distributions to noncontrolling interests											0	0	0
Proceeds from debt issuance and drawdown of revolver											225	450	0
Net proceeds from issuance of Westlake Partners common units											0
Proceeds from senior notes issuance											745	1,429
Repayment of term loan											0
Restricted cash associated with term loan											0	0
Repayment of notes payable											(251)	0	0
Repurchase of common stock for treasury												(67)	(163)
Repayment of revolver											(550)	(125)
Other											11	5	4
Net cash provided by (used for) financing activities											953	(639)	167
Effect of exchange rate changes on cash and cash equivalents											0	0	0
Net increase (decrease) in cash and cash equivalents											942	(156)	(353)
Cash and cash equivalents at beginning of the year						147				303	147	303	656
Cash and cash equivalents at end of the year			1,089				147				1,089	147	303
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)											822	(36)	260
Depreciation and amortization											395	217	114
Deferred income taxes											(535)	103	39
Net changes in working capital and other											41	90	93
Net cash provided by operating activities											723	374	506
Acquisition of business, net of cash acquired											(13)	(2,502)	0
Additions to property, plant and equipment											(407)	(275)	(215)
Additions to cost method investment											(66)	(17)
Proceeds from disposition of equity method investment													28
Proceeds from sales and maturities of securities												0	0
Purchase of securities												0	(49)
Other											2	(4)	(3)
Net cash used for investing activities											(484)	(2,798)	(239)
Intercompany financing											(611)	2,207	(590)
Receivable under the investment management agreement											0
Debt issuance costs											0	0
Dividends paid											0	0	0
Distributions to noncontrolling interests											376	263	327
Proceeds from debt issuance and drawdown of revolver											0	0	0
Net proceeds from issuance of Westlake Partners common units											0
Proceeds from senior notes issuance											0	0
Repayment of term loan											0
Restricted cash associated with term loan											0	0
Repayment of notes payable											0	0	0
Repurchase of common stock for treasury												0	0
Repayment of revolver											0	0
Other											0	0	0
Net cash provided by (used for) financing activities											(235)	2,470	(263)
Effect of exchange rate changes on cash and cash equivalents											0	0	0
Net increase (decrease) in cash and cash equivalents											4	46	4
Cash and cash equivalents at beginning of the year						53				7	53	7	3
Cash and cash equivalents at end of the year			57				53				57	53	7
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)											531	457	423
Depreciation and amortization											206	161	132
Deferred income taxes											(11)	(3)	1
Net changes in working capital and other											100	(118)	30
Net cash provided by operating activities											826	497	586
Acquisition of business, net of cash acquired											0	64	16
Additions to property, plant and equipment											(170)	(354)	(276)
Additions to cost method investment											0	0
Proceeds from disposition of equity method investment													0
Proceeds from sales and maturities of securities												5	0
Purchase of securities												0	0
Other											(134)	0	0
Net cash used for investing activities											(304)	(285)	(260)
Intercompany financing											(135)	(8)	172
Receivable under the investment management agreement											0
Debt issuance costs											0	(1)
Dividends paid											0	0	0
Distributions to noncontrolling interests											(404)	(280)	(342)
Proceeds from debt issuance and drawdown of revolver											8	158	53
Net proceeds from issuance of Westlake Partners common units											111
Proceeds from senior notes issuance											0	0
Repayment of term loan											(150)
Restricted cash associated with term loan											154	(154)
Repayment of notes payable											(6)	(13)	(74)
Repurchase of common stock for treasury												0	0
Repayment of revolver											0	0
Other											0	0	0
Net cash provided by (used for) financing activities											(422)	(298)	(191)
Effect of exchange rate changes on cash and cash equivalents											26	(8)	(4)
Net increase (decrease) in cash and cash equivalents											126	(94)	131
Cash and cash equivalents at beginning of the year						$ 259				$ 353	259	353	222
Cash and cash equivalents at end of the year			$ 385				$ 259				$ 385	$ 259	$ 353

Quarterly Financial Information (Summary Of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 2,010	$ 2,109	$ 1,979	$ 1,943	$ 1,735	$ 1,280	$ 1,086	$ 975	$ 8,041	$ 5,076	$ 4,463
Gross profit	498	498	405	368	282	203	241	255	1,769	981	1,185
Income from operations	365	366	266	236	153	46	180	202	1,233	581	960
Net income	816	219	159	145	105	70	116	129	1,339	420	665
Net income attributable to Westlake Chemical Corporation	$ 802	$ 211	$ 153	$ 138	$ 99	$ 66	$ 111	$ 123	$ 1,304	$ 399	$ 646
Basic (in dollars per share)	$ 6.18	$ 1.62	$ 1.18	$ 1.07	$ 0.76	$ 0.51	$ 0.85	$ 0.94	$ 10.05	$ 3.07	$ 4.88
Diluted (in dollars per share)	$ 6.15	$ 1.61	$ 1.17	$ 1.06	$ 0.76	$ 0.51	$ 0.85	$ 0.94	$ 10.00	$ 3.06	$ 4.86