Description of Business and Basis of Presentation	6 Months Ended
Jun. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Description of Business Westlake Corporation (the "Company") operates as an integrated global manufacturer and marketer of housing and infrastructure products and performance and essential materials. These products include some of the most widely used materials in the world, which are fundamental to many diverse consumer and industrial markets, including residential construction, flexible and rigid packaging, automotive products, healthcare products, materials used in turbines to generate wind energy, water treatment, coatings 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 throughout North America, Europe and Asia. Basis of Presentation The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto of the Company, included in the annual report on Form 10-K for the fiscal year ended December 31, 2025 (the "2025 Form 10-K"), filed with the SEC on February 26, 2026. These consolidated financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Company for the fiscal year ended December 31, 2025. In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as disclosed in Note 2 "Acquisitions") that are necessary for a fair statement of the Company's financial position as of June 30, 2026, its results of operations for the three and six months ended June 30, 2026 and 2025, and the changes in its cash position for the six months ended June 30, 2026 and 2025. Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2026 or any other interim period. The preparation of consolidated financial statements in conformity with U.S. GAAP 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. Recently Issued Accounting Pronouncements Environmental Credits and Environmental Credit Obligations (ASU 2026-02) In May 2026, the FASB issued an accounting standards update to establish authoritative guidance on recognition, measurement, presentation and disclosure of environmental credits and environmental credit obligations. The amendments define environmental credits as assets only if it is probable they will be used to settle an environmental credit obligation, transferred in an exchange transaction, or used in a nonreciprocal transfer. The amendments are effective for annual periods beginning after December 15, 2027 and interim reporting periods within those annual reporting periods, for public business entities, with early adoption permitted. The transition option is modified retrospective. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements. Accounting for Government Grants Received by Business Entities (ASU 2025-10) In December 2025, the FASB issued an accounting standards update to establish authoritative guidance on recognition, measurement, presentation, and disclosure of government grants received by business entities. The amendments define government grants as transfers of monetary or tangible non-monetary assets from a government to a business entity (excluding exchange transactions) and leverages principles from IAS 20 while tailoring certain U.S. GAAP requirements. The amendments are effective for annual periods beginning after December 15, 2028, and interim reporting periods within those annual reporting periods, for public business entities, with early adoption permitted. The transition options include modified prospective, modified retrospective, or full retrospective. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements. Hedge Accounting Improvements (ASU 2025-09) In November 2025, the FASB issued an accounting standards update to clarify and improve certain aspects of hedge accounting guidance in ASC 815. The amendments address five specific areas: (1) similar risk assessment for cash flow hedges, (2) hedging interest payments on choose-your-rate debt, (3) cash flow hedges of nonfinancial forecasted transactions, (4) net written options as hedging instruments, and (5) foreign currency-denominated debt designated as both a hedging instrument and hedged item. The amendments more closely align hedge accounting with the economics of an entity's risk management activities. The amendments are effective for annual periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods, for public business entities with early adoption permitted. Entities should apply the new guidance prospectively. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements. Targeted Improvements to the Accounting for Internal-Use Software (ASU 2025-06) In September 2025, the Financial Accounting Standards Board ("FASB") issued an accounting standards update to modernize the accounting for software costs to increase the operability of the recognition guidance considering different methods of software development and clarify the criteria for capitalizing software costs. The amendments are effective for annual reporting periods beginning after December 15, 2027 and interim reporting periods within those annual reporting periods, with an early adoption permitted as of the beginning of an annual reporting period. Entities should apply the new guidance either retrospectively, prospectively, or via a modified prospective transition method. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements. Disaggregation of Income Statement Expenses (ASU 2024-03) In November 2024, the FASB issued an accounting standards update requiring public entities to disclose, on an annual and interim basis, detailed information about the types of expenses in relevant expense captions presented on the face of the income statement, including amounts for inventory purchases, employee compensation, depreciation and amortization of intangible assets and a qualitative description for remaining amounts not separately disaggregated. Additionally, the update requires disclosure of total selling expenses, and in annual periods, an entity's definition of selling expenses. The amendments in this update are effective for annual reporting periods beginning after December 15, 2026, and interim periods beginning after December 15, 2027 and are to be applied either prospectively or retrospectively. The Company is currently evaluating the impact of the update on the disclosures in the Company's consolidated financial statements. Recently Adopted Accounting Pronouncements Measurement of Credit Losses for Accounts Receivable and Contract Assets (ASU 2025-05) In July 2025, the FASB issued an accounting standards update to add a practical expedient in developing reasonable and supportable forecasts as part of estimating expected credit losses. All entities may elect a practical expedient that assumes the current conditions as of the balance sheet date do not change for the remaining life of the asset. The amendments in this update are effective for annual reporting periods beginning after December 15, 2025 and interim reporting periods within those annual reporting periods, with early adoption permitted. Entities should apply the new guidance prospectively. The Company adopted the standard electing a practical expedient effective January 1, 2026, and the adoption of this accounting standard did not have a material impact on its consolidated statements of financial position, results of operations, or cash flows, or on related financial statement disclosures.

Westlake Corporation (the "Company") operates as an integrated global manufacturer and marketer of housing and infrastructure products and performance and essential materials. These products include some of the most widely used materials in the world, which are fundamental to many diverse consumer and industrial markets, including residential construction, flexible and rigid packaging, automotive products, healthcare products, materials used in turbines to generate wind energy, water treatment, coatings 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 throughout North America, Europe and Asia.

The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto of the Company, included in the annual report on Form 10-K for the fiscal year ended December 31, 2025 (the "2025 Form 10-K"), filed with the SEC on February 26, 2026. These consolidated financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Company for the fiscal year ended December 31, 2025.

In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as disclosed in Note 2 "Acquisitions") that are necessary for a fair statement of the Company's financial position as of June 30, 2026, its results of operations for the three and six months ended June 30, 2026 and 2025, and the changes in its cash position for the six months ended June 30, 2026 and 2025.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2026 or any other interim period. The preparation of consolidated financial statements in conformity with U.S. GAAP 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.

In May 2026, the FASB issued an accounting standards update to establish authoritative guidance on recognition, measurement, presentation and disclosure of environmental credits and environmental credit obligations. The amendments define environmental credits as assets only if it is probable they will be used to settle an environmental credit obligation, transferred in an exchange transaction, or used in a nonreciprocal transfer. The amendments are effective for annual periods beginning after December 15, 2027 and interim reporting periods within those annual reporting periods, for public business entities, with early adoption permitted. The transition option is modified retrospective. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements.

In December 2025, the FASB issued an accounting standards update to establish authoritative guidance on recognition, measurement, presentation, and disclosure of government grants received by business entities. The amendments define government grants as transfers of monetary or tangible non-monetary assets from a government to a business entity (excluding exchange transactions) and leverages principles from IAS 20 while tailoring certain U.S. GAAP requirements. The amendments are effective for annual periods beginning after December 15, 2028, and interim reporting periods within those annual reporting periods, for public business entities, with early adoption permitted. The transition options include modified prospective, modified retrospective, or full retrospective. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements.

In November 2025, the FASB issued an accounting standards update to clarify and improve certain aspects of hedge accounting guidance in ASC 815. The amendments address five specific areas: (1) similar risk assessment for cash flow hedges, (2) hedging interest payments on choose-your-rate debt, (3) cash flow hedges of nonfinancial forecasted transactions, (4) net written options as hedging instruments, and (5) foreign currency-denominated debt designated as both a hedging instrument and hedged item. The amendments more closely align hedge accounting with the economics of an entity's risk management activities. The amendments are effective for annual periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods, for public business entities with early adoption permitted. Entities should apply the new guidance prospectively. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements.

In September 2025, the Financial Accounting Standards Board ("FASB") issued an accounting standards update to modernize the accounting for software costs to increase the operability of the recognition guidance considering different methods of software development and clarify the criteria for capitalizing software costs. The amendments are effective for annual reporting periods beginning after December 15, 2027 and interim reporting periods within those annual reporting periods, with an early adoption permitted as of the beginning of an annual reporting period. Entities should apply the new guidance either retrospectively, prospectively, or via a modified prospective transition method. The Company is in the process of evaluating the impact of this standard on the Company's consolidated financial statements.

In November 2024, the FASB issued an accounting standards update requiring public entities to disclose, on an annual and interim basis, detailed information about the types of expenses in relevant expense captions presented on the face of the income statement, including amounts for inventory purchases, employee compensation, depreciation and amortization of intangible assets and a qualitative description for remaining amounts not separately disaggregated. Additionally, the update requires disclosure of total selling expenses, and in annual periods, an entity's definition of selling expenses. The amendments in this update are effective for annual reporting periods beginning after December 15, 2026, and interim periods beginning after December 15, 2027 and are to be applied either prospectively or retrospectively. The Company is currently evaluating the impact of the update on the disclosures in the Company's consolidated financial statements.

In July 2025, the FASB issued an accounting standards update to add a practical expedient in developing reasonable and supportable forecasts as part of estimating expected credit losses. All entities may elect a practical expedient that assumes the current conditions as of the balance sheet date do not change for the remaining life of the asset. The amendments in this update are effective for annual reporting periods beginning after December 15, 2025 and interim reporting periods within those annual reporting periods, with early adoption permitted. Entities should apply the new guidance prospectively. The Company adopted the standard electing a practical expedient effective January 1, 2026, and the adoption of this accounting standard did not have a material impact on its consolidated statements of financial position, results of operations, or cash flows, or on related financial statement disclosures.