Net income (loss) attributable to common stockholders Net Income Loss Available To Common Stockholders Net income available to common stockholders after adjustments for net income attributable to participating securities. Deferred turnaround costs, net Deferred Turnaround Costs, Net Deferred Turnaround Costs, Net Statistical Measurement [Domain] Statistical Measurement [Domain] Expected restructuring charges remaining Restructuring and Related Cost, Expected Cost Remaining Property, plant and equipment recognized Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment Debt Securities, Available-for-Sale Debt Securities, Available-for-Sale [Table Text Block] Direct Purchasers Direct Purchasers [Member] Direct Purchasers 3.6% Senior Notes Due 2026 Three Point Six Percent Senior Notes Due Twenty Twenty-Six [Member] Three Point Six Percent Senior Notes Due Twenty Twenty-Six [Member] Settled Litigation Settled Litigation [Member] 5.55% Senior Notes Due November 2035 5.55% Senior Notes Due November 2035 [Member] 5.55% Senior Notes Due November 2035 Earnings and Dividends Per Share [Abstract] Earnings and Dividends Per Share [Abstract] Earnings and Dividends Per Share [Abstract] Award Timing Predetermined Award Timing Predetermined [Flag] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, Tax OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, Tax Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] Tabular List, Table Tabular List [Table Text Block] Supplemental Information Additional Financial Information Disclosure [Text Block] Recently Issued Accounting Pronouncements and Recently Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Line of credit permitted increase Line Of Credit Facility Permitted Increase The permitted amount the line of credit facility may be increased by, under certain circumstances if certain lenders agree to commit to such an increase. Accounts payable Increase (Decrease) in Accounts Payable Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] Summary Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Type of Restructuring [Domain] Type of Restructuring [Domain] Goodwill [Line Items] Goodwill [Line Items] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic (in dollars per share) Earnings Per Share, Basic Adjustment to Compensation: Adjustment to Compensation [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Other comprehensive income (loss), net of income taxes Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Segment Reporting Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Accrued Liabilities and Other Liabilities [Abstract] Accrued Liabilities and Other Liabilities [Abstract] Remaining performance obligations Revenue, Remaining Performance Obligation, Amount Adjustment to Compensation, Amount Adjustment to Compensation Amount Unamortized discount and debt issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Notes and other short-term payable Notes and Loans Payable, Current Stock-based compensation expense Share-Based Payment Arrangement, Noncash Expense Options Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Dismissed Litigation Dismissed Litigation [Member] Dismissed Litigation Income tax benefit (provision) on foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts and Financing Receivables [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Dividends declared Dividends, Common Stock, Cash Total Westlake Corporation stockholders' equity Equity, Attributable to Parent Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] Insider Trading Policies and Procedures [Line Items] Common stock, shares authorized Common Stock, Shares Authorized Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current assets Assets, Current [Abstract] Total liabilities and equity Liabilities and Equity Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Pension and Other Post-Retirement Benefits Liability, Net of Tax Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Cover [Abstract] Cover [Abstract] Maximum Maximum [Member] Schedule of Equity Method Investments [Table] Equity Method Investment [Table] Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Litigation Plaintiffs [Axis] Litigation Plaintiffs [Axis] Litigation Plaintiffs Capital expenditures Segment, Expenditure, Addition to Long-Lived Assets Customer relationships, net Finite-Lived Intangible Assets, Net After ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Loss from disposition and write-off of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Common Stock, Held in Treasury Treasury Stock, Common [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Pay vs Performance Disclosure [Line Items] Investment, Beginning Balance Investment, Ending Balance Investment Owned, Fair Value U.S. federal agency securities US Government Agencies Debt Securities [Member] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Acquisition Business Combination [Text Block] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Percentage of principal amount redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Other liabilities Other Liabilities, Noncurrent Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Impairment of goodwill and long-lived assets Goodwill, Impairment Loss Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Current portion of long-term debt, net Current portion Long-Term Debt, Current Maturities Other intangible assets, net Other Intangible Assets, Net Company Selected Measure Amount Company Selected Measure Amount 5.0% Senior Notes Due 2046 Five Percent Senior Notes Due Twenty Forty-Six [Member] Five Percent Senior Notes Due Twenty Forty-Six [Member] Comprehensive income attributable to noncontrolling interests, net of tax of $1 and $0 for the three months ended June 30, 2026 and 2025, respectively; and net of tax of $2 and $1 for the six months ended June 30, 2026 and 2025, respectively Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Comprehensive income (loss) attributable to Westlake Corporation Comprehensive Income (Loss), Net of Tax, Attributable to Parent Name Measure Name Balances at beginning of period Balances at end of period Restructuring Reserve Letter of Credit Letter of Credit [Member] Within one year Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Operating lease liabilities, current Operating Lease, Liability, Current Partners' capital, sold in public offering (in shares) Partners' Capital Account, Units, Sold in Public Offering Deferred income taxes Deferred Income Tax Liabilities, Net Document Fiscal Period Focus Document Fiscal Period Focus Award Timing Method Award Timing Method [Text Block] Litigation Case [Domain] Litigation Case [Domain] Award Type Award Type [Axis] Cumulative Foreign Currency Exchange, Net of Tax Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Contractual maturities of debt securities Available-for-Sale Securities, Debt Maturities [Abstract] Long-term debt, carrying value Carrying Value Long-Term Debt Total assets Total assets Assets Sulphur Brine Dome Sulphur Brine Dome [Member] Sulphur Brine Dome Investment, Name [Domain] Investment, Name [Domain] Trading Symbol Trading Symbol Shares issued—stock- based compensation (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Entity Address, City or Town Entity Address, City or Town Cash flows from operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Intangible assets useful life Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Effect of exchange rate changes on cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Inventories Inventory Disclosure [Text Block] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount ACI ACI [Member] ACI Credit Agreement Credit Agreement [Member] Credit Agreement [Member] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Damages awarded Loss Contingency, Damages Awarded, Value Business combination, consideration transferred Business Combination, Consideration Transferred Entity Emerging Growth Company Entity Emerging Growth Company Dividends per common share (in usd per share) Common Stock, Dividends, Per Share, Declared Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Debt Securities, Available-for-Sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Accrued rebates Accrued Rebates, Current Accrued Rebates, Current Unamortized debt issuance costs Debt Issuance Costs, Net PVC Pipe Antitrust PVC Pipe Antitrust [Member] PVC Pipe Antitrust Restricted cash and cash equivalents Restricted Cash and Cash Equivalent Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Equity method investments Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Combination [Domain] Business Combination [Domain] Related Party Related Party [Member] Contract with Customer, Liability [Roll Forward] Contract with Customer, Liability [Roll Forward] Contract with Customer, Liability Document Information [Table] Document Information [Table] PEO PEO [Member] Accounts Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Severance and Separation Costs Employee Severance [Member] Equity Method Investments Activity [Roll Forward] Equity Method Investments Activity [Roll Forward] Equity Method Investments Activity Other assets, net Deferred Costs and Other Assets Noncash Investing and Financing Items [Abstract] Noncash Investing and Financing Items [Abstract] 3.50% Senior Notes Due 2032 Three Point Five Zero Percent Senior Notes Due Twenty Thirty Two [Member] Three Point Five Zero Percent Senior Notes Due Twenty Thirty Two [Member] Changes in operating assets and liabilities, net of effect of business acquisitions Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Indirect Purchasers Indirect Purchasers [Member] Indirect Purchasers Retained Earnings Retained Earnings [Member] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Cash, cash equivalents and restricted cash at beginning of period Cash, cash equivalents and restricted cash at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Provision for income taxes Provision for (benefit from) income taxes Income Tax Expense (Benefit) Contract Termination and Other Costs Facility Closing [Member] Spread on variable rate Debt Instrument, Basis Spread on Variable Rate Infrastructure Products Infrastructure Products [Member] Infrastructure Products Document Information [Line Items] Document Information [Line Items] Earnings (Loss) and Dividends per Share Earnings and Dividends Per Share [Text Block] Earnings and Dividends Per Share [Text Block] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Product and Service [Domain] Product and Service [Domain] Available-for-sale debt securities Debt Securities, Available-for-Sale [Abstract] Net income (loss) Net income (loss) Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Business Combination [Table] Business Combination [Table] 6.375% Senior Notes Due November 2055 6.375% Senior Notes Due November 2055 [Member] 6.375% Senior Notes Due November 2055 Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Business Combination, Recognized Asset Acquired and Liability Assumed Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Accelerated Depreciation and Amortization Accelerated Depreciation and Amortization [Member] Accelerated Depreciation and Amortization Goodwill acquired during the period Goodwill, Acquired During Period City Area Code City Area Code Acquisitions of businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Accrued and other liabilities Accrued Liabilities, Current Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Contract with Customer, Contract Asset, Contract Liability, and Receivable Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Restructuring, transaction and integration-related costs Restructuring, transaction and integration-related costs Restructuring, transaction and integration-related costs Cash flows from investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Ethylene Antitrust Litigation Proceedings Ethylene Antitrust Litigation Proceedings [Member] Ethylene Antitrust Litigation Proceedings Preferred stock, par value, in dollars per share Preferred Stock, Par or Stated Value Per Share Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Goodwill Net goodwill at beginning of period Net goodwill at end of period Goodwill Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Equity Components [Axis] Equity Components [Axis] Standby Letters of Credit Standby Letters of Credit [Member] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Number of reportable segments Number of Reportable Segments Environmental exit costs, reasonably possible additional loss Environmental Exit Costs, Reasonably Possible Additional Loss Supplemental Cash Flow Information [Abstract] Supplemental Cash Flow Information [Abstract] Cost Cost Debt Securities, Available-for-Sale, Amortized Cost Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Goodwill accumulated impairment losses Goodwill, Impaired, Accumulated Impairment Loss Other Performance Measure, Amount Other Performance Measure, Amount Entity Address, State or Province Entity Address, State or Province Antidilutive Security, Excluded EPS Calculation [Table] Antidilutive Security, Excluded EPS Calculation [Table] Related Party [Domain] Related and Nonrelated Parties [Domain] Westlake Chemical OpCo LP Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Total current liabilities Liabilities, Current Term Loan Due 2026 Term Loan Due Twenty Twenty Six [Member] Term Loan Due Twenty Twenty Six Litigation Status [Axis] Litigation Status [Axis] Cumulative charges recognized Restructuring and Related Cost, Cost Incurred to Date Individual: Individual [Axis] Westlake Chemical Partners LP Westlake Chemical Partners LP [Member] Westlake Chemical Partners LP [Member] Dividends paid Payments of Ordinary Dividends, Common Stock Additional paid-in capital Additional Paid in Capital, Common Stock Net cash used for investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Remaining performance obligation term Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] 3.125% Senior Notes Due 2051 Three Point One Two Five Percent Senior Notes Due Twenty Fifty One [Member] Three Point One Two Five Percent Senior Notes Due Twenty Fifty One 4.375% Senior Notes Due 2047 Four Point Three Seven Five Percent Senior Notes Due Twenty Forty Seven [Member] Four Point Three Seven Five Percent Senior Notes Due Twenty Forty Seven [Member] Document Fiscal Year Focus Document Fiscal Year Focus Basis of Financial Statements Basis of Accounting, Policy [Policy Text Block] Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Repayment of senior notes Repayment of senior notes Repayments of Long-Term Debt Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Entity Interactive Data Current Entity Interactive Data Current Equity [Abstract] Equity [Abstract] Foreign currency translation gain (loss) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Legal fee and procedural fine percent Litigation Settlement, Legal Fee and Procedural Fine Percentage Litigation Settlement, Legal Fee and Procedural Fine Percentage Segment Information Segment Reporting Disclosure [Text Block] 1.625% Senior Notes Due 2029 One Point Six Two Five Percentage Senior Notes Due Twenty Twenty Nine [Member] One Point Six Two Five Percentage Senior Notes Due Twenty Twenty Nine Schedule of Goodwill [Table] Goodwill [Table] U.S. government treasury securities US Treasury Securities [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Ownership [Domain] Ownership [Domain] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Accumulated Other Comprehensive Loss Comprehensive Income (Loss) Note [Text Block] Amortization of intangibles Amortization of Intangible Assets Selling, general and administrative expenses Selling, General and Administrative Expense Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Depreciation and amortization Depreciation, Depletion and Amortization Entity Central Index Key Entity Central Index Key PEO Name PEO Name Net sales Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Revolving Credit Facility Revolving Credit Facility [Member] Arrangement Duration Trading Arrangement Duration Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Financial Instruments Financial Instruments Disclosure [Text Block] Depreciation and amortization segment expenses Depreciation and amortization segment expenses Depreciation and amortization segment expenses Segments [Axis] Segments [Axis] Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Limited Partner Limited Partner [Member] Local Phone Number Local Phone Number Class of Stock [Domain] Class of Stock [Domain] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Trade customers Accounts Receivable, before Allowance for Credit Loss, Current U.S. federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Other, net Payment for (Proceeds from) Other Investing Activity Other losses, net Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Intangible assets acquired Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill ASSETS Assets [Abstract] Long-term debt, net Long-term debt, carrying value, net of current portion Long-Term Debt, Excluding Current Maturities Credit Facility [Axis] Credit Facility [Axis] Nonrelated Party Nonrelated Party [Member] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Debt Instrument [Axis] Debt Instrument [Axis] Fair Value Measurements Fair Value Disclosures [Text Block] Business Combination [Line Items] Business Combination [Line Items] Credit Facility [Domain] Credit Facility [Domain] Stockholders' equity Equity, Attributable to Parent [Abstract] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Common stock repurchased Treasury Stock, Value, Acquired, Cost Method Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Investment, Name [Axis] Investment, Name [Axis] Stated interest rate (percent) Debt Instrument, Interest Rate, Stated Percentage Allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Operating lease liabilities Operating Lease, Liability, Noncurrent Partners' Capital [Abstract] Partners' Capital [Abstract] Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Ownership [Axis] Ownership [Axis] Subsidiary of Common Parent Subsidiary of Common Parent [Member] Fair Value as of Grant Date Award Grant Date Fair Value Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Schedule Of Long-Term Debt Schedule of Long-Term Debt Instruments [Table Text Block] Accounts and Notes Payable [Line Items] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Advance payment representing fixed portion of total transaction price Contract with Customer, Liability, Payment Advance Advance payment representing fixed portion of total transaction price Document Quarterly Report Document Quarterly Report Depreciation and amortization Investments in and Advances to Affiliates, at Fair Value, Gross Reductions Fair Value Long-Term Debt, Fair Value Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Number of operating segments Number of Operating Segments Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Schedule of Accounts Payable Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Asset Write-offs Inventory Write-Down [Member] Inventory Write-Down Swingline Loan Swingline Loan [Member] Swingline Loan [Member] Related Party [Axis] Related and Nonrelated Parties [Axis] Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Restatement Determination Date: Restatement Determination Date [Axis] Shares issued—stock-based compensation Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Non-PEO NEO Non-PEO NEO [Member] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Restructuring and Related Costs Restructuring and Related Costs [Table Text Block] Other, net Proceeds from (Payment for) Other Financing Activity Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Name Trading Arrangement, Individual Name All Award Types Award Type [Domain] New Credit Agreement New Credit Agreement [Member] New Credit Agreement [Member] Housing and Infrastructure Products Segment Housing and Infrastructure Products [Member] Housing and Infrastructure Products Goodwill Goodwill Disclosure [Text Block] Noncontrolling interests Equity, Attributable to Noncontrolling Interest Equity Awards Adjustments Equity Awards Adjustments [Member] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Accounts receivable Increase (Decrease) in Accounts and Other Receivables Compensation Amount Outstanding Recovery Compensation Amount Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Income tax provision on pension and other post-retirement benefits liability Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Essential Materials Essential Materials [Member] Essential Materials Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Revenues recognized that were included in the contract liability balances at the beginning of the period Contract with Customer, Liability, Revenue Recognized MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] One to five years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Name Awards Close in Time to MNPI Disclosures, Individual Name Payments Payments for Restructuring Restructuring Type [Axis] Restructuring Type [Axis] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Six to ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Common stock, held in treasury, at cost; 6,854,931 and 6,740,232 shares at June 30, 2026 and December 31, 2025, respectively Treasury Stock, Value Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Financial Instruments [Domain] Financial Instruments [Domain] Unrealized holding losses on investments OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Litigation Case [Axis] Litigation Case [Axis] Foreign currency translation adjustments Foreign Currency Translation Adjustment, by Component [Abstract] Segments [Domain] Segments [Domain] Damages sought Loss Contingency, Damages Sought, Value Performance Stock Units Performance Shares [Member] Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Chlorovinyls and Styrene Facility Closure Chlorovinyls and Styrene Facility Closure [Member] Chlorovinyls and Styrene Facility Closure Inventories Increase (Decrease) in Inventories Inventories Inventories Inventory, Net LACC, LLC LACC, LLC [Member] LACC, LLC [Member] Minimum Minimum [Member] Net income (loss) attributable to participating securities Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted Available-for-sale Securities, Net of Tax AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Goodwill, Measurement Period Adjustment Goodwill, Measurement Period Adjustment Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Company Selected Measure Name Company Selected Measure Name Environmental contingency accrual Accrual for Environmental Loss Contingencies Senior Notes Senior Notes [Member] Purchase of available-for-sale securities Payments to Acquire Debt Securities, Available-for-Sale Long-Term Debt Debt Disclosure [Text Block] Preferred stock, $0.01 par value, 50,000,000 shares authorized; no shares issued and outstanding Preferred Stock, Value, Issued Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts payable Accounts payable Accounts Payable, Current Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] All Executive Categories All Executive Categories [Member] Finished products Inventory, Finished Goods, Net of Reserves Common stock, $0.01 par value, 300,000,000 shares authorized; 134,651,380 and 134,651,380 shares issued at June 30, 2026 and December 31, 2025, respectively Common Stock, Value, Issued Restructuring Plan [Domain] Restructuring Plan [Domain] Goodwill [Roll Forward] Goodwill [Roll Forward] Additions to investments in unconsolidated subsidiaries Return of (additions to) investment from unconsolidated subsidiaries Return of (additions to) investment from unconsolidated subsidiaries Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Diluted (in shares) Weighted average common shares—diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Commitments and contingencies (Note 14) Commitments and Contingencies Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Reconciliation of Assets from Segment to Consolidated [Table] Reconciliation of Assets from Segment to Consolidated [Table] Business Combination [Axis] Business Combination [Axis] Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Entity Small Business Entity Small Business Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Litigation Plaintiffs [Domain] Litigation Plaintiffs [Domain] Litigation Plaintiffs [Domain] Noncontrolling Interests Noncontrolling Interest [Member] Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Document Transition Report Document Transition Report One to five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Ownership interest (percent) Equity Method Investment, Ownership Percentage Underlying Securities Award Underlying Securities Amount Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount After ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Income Taxes Income Tax Disclosure [Text Block] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Total equity Beginning balances Ending balances Equity, Including Portion Attributable to Noncontrolling Interest Document Type Document Type Total Assets Reconciliation of Assets from Segment to Consolidated [Table Text Block] Name Outstanding Recovery, Individual Name Environmental Loss Contingencies [Table] Loss Contingencies [Table] Product and Service [Axis] Product and Service [Axis] Raw material, energy and manufacturing costs Raw material, energy and manufacturing costs Raw material, energy and manufacturing costs Litigation Status [Domain] Litigation Status [Domain] All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Performance and Essential Materials Segment Performance and Essential Materials [Member] Performance and Essential Materials Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Additions to property, plant and equipment Payments to Acquire Property, Plant, and Equipment Name Forgone Recovery, Individual Name Total current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] 2.875% Senior Notes Due 2041 2.875% Senior Notes Due 2041 [Member] 2.875% Senior Notes Due 2041 Schedule Of Net Income Attributable To Common Stockholders Schedule Of Net Income Loss Attributable To Common Stockholders [Table Text Block] Schedule of net income (loss) attributable to common stockholders [Table Text Block] Materials and supplies Inventory, Supplies, Net of Reserves Loss contingency accrual Loss Contingency Accrual Undrawn commitment fee percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Loan related to tax-exempt waste disposal revenue bonds due 2027 Waste Disposal Revenue Bonds Due Twenty Twenty Seven [Member] Waste Disposal Revenue Bonds Due Twenty Twenty-Seven [Member] Other Other Receivables, Net, Current Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Depreciation and amortization Depreciation and amortization SG&A Depreciation and amortization SG&A Effects of changes in foreign exchange rates Goodwill, Foreign Currency Translation, Gain (Loss) Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Net 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