Basis of Financial Statements (Policies)	9 Months Ended
Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Financial Statements	Basis of Financial Statements 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 December 31, 2014 financial statements and notes thereto of Westlake Chemical Corporation (the "Company") included in the annual report on Form 10-K for the fiscal year ended December 31, 2014 (the "2014 Form 10-K"), filed with the SEC on February 25, 2015. These 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, 2014. In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of September 30, 2015, its results of operations for the three and nine months ended September 30, 2015 and 2014 and the changes in its cash position for the nine months ended September 30, 2015 and 2014. 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, 2015 or any other interim period. The preparation of 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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Revenue from Contracts with Customers 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 2015, the FASB deferred the effective date for the revenue recognition standard. The accounting standard will now be effective for reporting periods beginning after December 15, 2017. 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. Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items In January 2015, the FASB issued an accounting standards update to simplify income statement classification by removing the concept of extraordinary items from U.S. GAAP. Under the new standard, an unusual and infrequent event or transaction is no longer allowed to be separately disclosed as "extraordinary." The standard retains the existing requirement to separately present items that are of an unusual nature or occur infrequently on a pre-tax basis within income from continuing operations. The new guidance also requires similar separate presentation of items that are both unusual and infrequent on a pre-tax basis within income from continuing operations. The standard allows for either prospective or retrospective application. If adopted prospectively, both the nature and amount of any subsequent adjustments to previously reported extraordinary items must be disclosed. The accounting standard will be effective for reporting periods beginning after December 15, 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows. Amendments to the Consolidation Analysis In February 2015, the FASB issued an accounting standards update making certain changes to the current consolidation guidance. The amendments affect both the variable interest entity and voting interest entity consolidation models. The new standard changes the consideration of substantive rights, related party interests and fees paid to the decision maker when applying the variable interest entity consolidation model and eliminates certain guidance for limited partnerships and similar entities under the voting interest consolidation model. The accounting standard will be effective for annual periods beginning after December 15, 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows. Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued an accounting standards update on simplifying the presentation of debt issuance costs, which requires all costs incurred to issue debt to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of a debt discount. The accounting standard will be effective for reporting periods beginning after December 15, 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows. Simplifying the Measurement of Inventory In July 2015, the FASB issued an accounting standards update that requires entities to measure inventory at the lower of cost or net realizable value rather than at the lower of cost or market. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. Under the new standard, entities will no longer need to calculate other measures of "market." The new accounting guidance applies only to inventories for which cost is determined by methods other than last-in first-out and the retail inventory method. The accounting standard will be effective for reporting periods beginning after December 15, 2016 and is not expected to have a significant impact on the Company's consolidated financial position, results of operations and cash flows. Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements In August 2015, the FASB issued final guidance incorporating into the Accounting Standards Codification a June 2015 SEC staff announcement that the SEC staff will not object to an entity presenting the cost of securing a revolving line of credit as an asset, regardless of whether a balance is outstanding. The announcement came in response to questions that arose after the FASB issued the Simplifying the Presentation of Debt Issuance Costs standard in April 2015, which standard requires debt issuance costs related to a recognized debt liability to be presented in the balance sheet as a direct deduction from the debt liability rather than as an asset. That standard, as issued, did not address revolving lines of credit, which may not have outstanding balances. An entity that repeatedly draws on a revolving credit facility and then repays the balance could also present the cost as an asset and reclassify all or a portion of it as a direct deduction from the liability whenever a balance is outstanding. Regardless of asset or contra-liability presentation, debt issuance costs should be amortized over the term of the arrangement. The accounting standard became effective upon announcement in June 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows. Simplifying the Accounting for Measurement-Period Adjustments In September 2015, the FASB issued an accounting standards update that requires an acquirer to recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The guidance requires that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The new guidance further requires specific disclosure pertaining to the measurement period adjustments. The accounting standard will be effective for reporting periods beginning after December 15, 2015 and is not expected to have a significant impact on the Company's consolidated financial position, results of operations and cash flows.

Recent Accounting Pronouncements

Revenue from Contracts with Customers

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 2015, the FASB deferred the effective date for the revenue recognition standard. The accounting standard will now be effective for reporting periods beginning after December 15, 2017. 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.

Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items

In January 2015, the FASB issued an accounting standards update to simplify income statement classification by removing the concept of extraordinary items from U.S. GAAP. Under the new standard, an unusual and infrequent event or transaction is no longer allowed to be separately disclosed as "extraordinary." The standard retains the existing requirement to separately present items that are of an unusual nature or occur infrequently on a pre-tax basis within income from continuing operations. The new guidance also requires similar separate presentation of items that are both unusual and infrequent on a pre-tax basis within income from continuing operations. The standard allows for either prospective or retrospective application. If adopted prospectively, both the nature and amount of any subsequent adjustments to previously reported extraordinary items must be disclosed. The accounting standard will be effective for reporting periods beginning after December 15, 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows.

Amendments to the Consolidation Analysis

In February 2015, the FASB issued an accounting standards update making certain changes to the current consolidation guidance. The amendments affect both the variable interest entity and voting interest entity consolidation models. The new standard changes the consideration of substantive rights, related party interests and fees paid to the decision maker when applying the variable interest entity consolidation model and eliminates certain guidance for limited partnerships and similar entities under the voting interest consolidation model. The accounting standard will be effective for annual periods beginning after December 15, 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows.

Simplifying the Presentation of Debt Issuance Costs

In April 2015, the FASB issued an accounting standards update on simplifying the presentation of debt issuance costs, which requires all costs incurred to issue debt to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of a debt discount. The accounting standard will be effective for reporting periods beginning after December 15, 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows.

Simplifying the Measurement of Inventory

In July 2015, the FASB issued an accounting standards update that requires entities to measure inventory at the lower of cost or net realizable value rather than at the lower of cost or market. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. Under the new standard, entities will no longer need to calculate other measures of "market." The new accounting guidance applies only to inventories for which cost is determined by methods other than last-in first-out and the retail inventory method. The accounting standard will be effective for reporting periods beginning after December 15, 2016 and is not expected to have a significant impact on the Company's consolidated financial position, results of operations and cash flows.

Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements

In August 2015, the FASB issued final guidance incorporating into the Accounting Standards Codification a June 2015 SEC staff announcement that the SEC staff will not object to an entity presenting the cost of securing a revolving line of credit as an asset, regardless of whether a balance is outstanding. The announcement came in response to questions that arose after the FASB issued the Simplifying the Presentation of Debt Issuance Costs standard in April 2015, which standard requires debt issuance costs related to a recognized debt liability to be presented in the balance sheet as a direct deduction from the debt liability rather than as an asset. That standard, as issued, did not address revolving lines of credit, which may not have outstanding balances. An entity that repeatedly draws on a revolving credit facility and then repays the balance could also present the cost as an asset and reclassify all or a portion of it as a direct deduction from the liability whenever a balance is outstanding. Regardless of asset or contra-liability presentation, debt issuance costs should be amortized over the term of the arrangement. The accounting standard became effective upon announcement in June 2015 and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows.

Simplifying the Accounting for Measurement-Period Adjustments

In September 2015, the FASB issued an accounting standards update that requires an acquirer to recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The guidance requires that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The new guidance further requires specific disclosure pertaining to the measurement period adjustments. The accounting standard will be effective for reporting periods beginning after December 15, 2015 and is not expected to have a significant impact on the Company's consolidated financial position, results of operations and cash flows.