Westlake (WLK) 10-Q 4 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 27, 2016
Document Documentand Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Trading Symbol	WLK
Entity Registrant Name	WESTLAKE CHEMICAL CORP
Entity Central Index Key	1,262,823
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		130,306,311

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 614,976	$ 662,525
Marketable securities	525,008	520,144
Accounts receivable, net	549,037	508,532
Inventories	478,656	434,060
Prepaid expenses and other current assets	24,057	14,489
Deferred income taxes	0	35,439
Total current assets	2,191,734	2,175,189
Property, plant and equipment, net	3,114,821	3,004,067
Equity investments	9,431	9,208
Other assets, net
Intangible assets, net	213,508	213,404
Deferred costs and other assets	194,907	167,417
Total other assets, net	408,415	380,821
Total assets	5,724,401	5,569,285
Current liabilities
Accounts and notes payable	257,384	235,329
Accrued liabilities	248,777	287,313
Total current liabilities	506,161	522,642
Long-term debt, net	758,300	758,148
Deferred income taxes	609,752	575,603
Other liabilities	145,786	150,961
Total liabilities	$ 2,019,999	$ 2,007,354
Commitments and contingencies (Notes 8 and 18)
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; 134,663,244 shares issued at March 31, 2016 and December 31, 2015	1,347	1,347
Common stock, held in treasury, at cost; 4,372,222 and 4,444,898 shares at March 31, 2016 and December 31, 2015, respectively	(256,459)	(258,312)
Additional paid-in capital	542,886	542,148
Retained earnings	3,209,415	3,109,987
Accumulated other comprehensive loss	(90,663)	(129,292)
Total Westlake Chemical Corporation stockholders' equity	3,406,526	3,265,878
Noncontrolling interests	297,876	296,053
Total equity	3,704,402	3,561,931
Total liabilities and equity	$ 5,724,401	$ 5,569,285

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 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	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	134,663,244	134,663,244
Common stock, held in treasury	4,372,222	4,444,898

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Net sales	$ 975,187	$ 1,103,531
Cost of sales	719,602	818,985
Gross profit	255,585	284,546
Selling, general and administrative expenses	53,309	55,266
Income from operations	202,276	229,280
Other income (expense)
Interest expense	(6,685)	(9,591)
Other income, net	2,645	9,096
Income before income taxes	198,236	228,785
Provision for income taxes	69,300	78,378
Net income	128,936	150,407
Net income attributable to noncontrolling interests	5,808	4,065
Net income attributable to Westlake Chemical Corporation	$ 123,128	$ 146,342
Earnings per common share attributable to Westlake Chemical Corporation
Basic (usd per share)	$ 0.94	$ 1.10
Diluted (usd per share)	$ 0.94	$ 1.10
Weighted average shares outstanding:
Basic	130,189,964	132,714,566
Diluted	130,600,514	133,205,306
Dividends per common share	$ 0.1815	$ 0.1650

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 128,936	$ 150,407
Pension and other post-retirement benefits liability
Amortization of benefits liability	334	652
Income tax provision on pension and other post-retirement benefits liability	(128)	(225)
Foreign currency translation adjustments	22,805	(59,698)
Available-for-sale investments
Unrealized holding gains on investments	24,428	1,626
Reclassification of net realized gains to net income	(52)	0
Income tax provision on available-for-sale investments	(8,758)	(584)
Other comprehensive income (loss)	38,629	(58,229)
Comprehensive income	167,565	92,178
Comprehensive income attributable to noncontrolling interests, net of tax	5,808	4,065
Comprehensive income attributable to Westlake Chemical Corporation	$ 161,757	$ 88,113

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities
Net income	$ 128,936	$ 150,407
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	65,714	58,641
Recovery of doubtful accounts	148	(9)
Amortization of debt issuance costs	220	501
Stock-based compensation expense	2,303	2,340
Loss from disposition of property, plant and equipment	309	133
Gains from sales of securities	(52)	0
Deferred income taxes	58,637	5,331
Windfall tax benefits from share-based payment arrangements	(266)	(1,701)
Income from equity method investments, net of dividends	(223)	(3,416)
Other losses (gains), net	661	(554)
Changes in operating assets and liabilities
Accounts receivable	(36,324)	18,517
Inventories	(40,878)	35,979
Prepaid expenses and other current assets	(10,791)	(6,202)
Accounts payable	23,752	(3,625)
Accrued liabilities	(54,257)	(59,585)
Other, net	(8,954)	(6,201)
Net cash provided by operating activities	128,935	190,556
Cash flows from investing activities
Additions to property, plant and equipment	(136,328)	(95,822)
Proceeds from disposition of assets	104	0
Proceeds from sales and maturities of securities	26,859	0
Purchase of securities	(36,637)
Settlements of derivative instruments	(1,219)	(833)
Net cash used for investing activities	(147,221)	(96,655)
Cash flows from financing activities
Dividends paid	(23,700)	(21,964)
Distributions to noncontrolling interests	(3,985)	(3,558)
Proceeds from exercise of stock options	22	157
Proceeds from issuance of notes payable	2,050	0
Repayment of notes payable	(7,095)	0
Repurchase of common stock for treasury	(679)	(2,000)
Windfall tax benefits from share-based payment arrangements	266	1,701
Net cash provided by financing activities	(33,121)	(25,664)
Effect of exchange rate changes on cash and cash equivalents	3,858	(3,189)
Net (decrease) increase in cash and cash equivalents	(47,549)	65,048
Cash and cash equivalents at beginning of period	662,525	880,601
Cash and cash equivalents at end of period	$ 614,976	$ 945,649

Basis of Financial Statements

Basis of Financial Statements	3 Months Ended
	Mar. 31, 2016
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, 2015 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, 2015 (the " 2015 Form 10-K"), filed with the SEC on February 24, 2016 . 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, 2015 . 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 March 31, 2016 , its results of operations for the three months ended March 31, 2016 and 2015 and the changes in its cash position for the three months ended March 31, 2016 and 2015 . 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, 2016 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 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 March 2016, the FASB issued additional authoritative guidance to provide clarification on principal versus agent considerations included within the new revenue recognition standard. The accounting standard (including the clarification guidance issued in March 2016) will 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. Recognition and Measurement of Financial Assets and Financial Liabilities 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. 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. Leases 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. Stock Compensation 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. The accounting standard is effective for reporting periods beginning after December 15, 2016. 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 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 is effective for annual periods beginning after December 15, 2015. The Company adopted this accounting standard effective January 1, 2016 and the adoption did not have an impact on the Company's consolidated financial position, results of operations and cash flows. Intangibles—Goodwill and Other—Internal use software In April 2015, the FASB issued an accounting standards update to provide clarification on accounting for cloud computing arrangements which include a software license. The accounting standard is effective for annual periods beginning after December 15, 2015. The Company adopted this accounting standard, to be applied prospectively, effective January 1, 2016. Consistent with the prospective application of this accounting standard, prior period comparative information was not adjusted. The adoption did not have a material 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 is effective for reporting periods beginning after December 15, 2015. The Company adopted this accounting standard effective January 1, 2016. As a result, Other assets, net—Deferred charges and other assets, net and Long-term debt on the consolidated balance sheet as of December 31, 2015 have been adjusted to $167,417 and $758,148 , respectively, from the originally reported $173,384 and $764,115 , respectively, to reflect the retrospective application of the new accounting guidance. The adoption of this accounting standard did not have an impact on the Company's 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 is effective for reporting periods beginning after December 15, 2015. The Company adopted this accounting standard effective January 1, 2016 and the adoption did not have an impact on the Company's consolidated financial position, results of operations and cash flows. Balance Sheet Classification of Deferred Taxes In November 2015, the FASB issued an accounting standards update that requires all deferred tax assets and liabilities, along with any related valuation allowance, to be classified as noncurrent on the balance sheet. As a result, each jurisdiction will now only have one net noncurrent deferred tax asset or liability. The new guidance does not change the existing requirement that only permits offsetting within a jurisdiction. The accounting standard is required to be adopted for reporting periods beginning after December 15, 2016; however, early adoption of this standard is permitted. The Company elected to early adopt this accounting standard, to be applied prospectively, effective January 1, 2016. Consistent with the prospective application of this accounting standard, prior period comparative information was not adjusted. The early adoption of this accounting standard did not have an impact on the Company's results of operations and cash flows.

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Financial Instruments	Financial Instruments Cash Equivalents The Company had $292,903 and $221,918 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at March 31, 2016 and December 31, 2015 , respectively. The Company's investments in held-to-maturity securities are held at amortized cost, which approximates fair value. Available-for-Sale Marketable Securities Investments in available-for-sale securities were classified as follows: March 31, December 31, Current $ 525,008 $ 520,144 Non-current 75,114 48,081 Total available-for-sale securities $ 600,122 $ 568,225 The cost, gross unrealized gains, gross unrealized losses and fair value of the Company's available-for-sale securities were as follows: March 31, 2016 Cost Gross Gross (1) Fair Value Debt securities Corporate bonds $ 341,856 $ 1,411 $ (185 ) $ 343,082 U.S. government debt (2) 125,114 425 (9 ) 125,530 Asset-backed securities 56,289 120 (13 ) 56,396 Equity securities 60,283 14,927 (96 ) 75,114 Total available-for-sale securities $ 583,542 $ 16,883 $ (303 ) $ 600,122 December 31, 2015 Cost Gross Gross (1) Fair Value Debt securities Corporate bonds $ 336,665 $ 55 $ (1,076 ) $ 335,644 U.S. government debt (2) 135,226 2 (374 ) 134,854 Asset-backed securities 49,759 2 (115 ) 49,646 Equity securities 54,371 466 (6,756 ) 48,081 Total available-for-sale securities $ 576,021 $ 525 $ (8,321 ) $ 568,225 _____________ (1) All unrealized loss positions were held at a loss for less than 12 months. (2) U.S. Treasury obligations, U.S. government agency obligations and U.S government agency mortgage-backed securities. As of March 31, 2016 and December 31, 2015 , net unrealized gains (losses) on the Company's available-for-sale securities of $10,623 and $(4,995) , respectively, net of income tax expense (benefit) of $5,957 and $(2,801) , respectively, were recorded in accumulated other comprehensive loss. See Note 13 for the fair value hierarchy of the Company's available-for-sale securities. As of March 31, 2016 , the corporate bond securities held by the Company had maturities ranging between one month to five years ; the U.S. government debt securities held by the Company, excluding U.S. government agency mortgage-backed securities, had maturities ranging between one month to four years ; the U.S. government agency mortgage-backed securities held by the Company had maturities of approximately five years ; and the asset-backed securities held by the Company had maturities ranging between one month to five years . The proceeds from sales and maturities of available-for-sale securities included in the consolidated statement of cash flows and the gross realized gains and losses included in the consolidated statement of operations are reflected in the table below. The cost of securities sold was determined using the specific identification method. There were no sales or maturities of available-for-sale securities during the three months ended March 31, 2015. Three Months Ended March 31, 2016 Proceeds from sales and maturities of securities $ 26,859 Gross realized gains 61 Gross realized losses (9 )

Accounts Receivable

Accounts Receivable	3 Months Ended
	Mar. 31, 2016
Accounts Receivable, Net [Abstract]
Accounts Receivable	Accounts Receivable Accounts receivable consist of the following: March 31, December 31, Trade customers $ 465,697 $ 438,538 Allowance for doubtful accounts (14,321 ) (14,095 ) 451,376 424,443 Federal and state taxes 81,255 60,748 Other 16,406 23,341 Accounts receivable, net $ 549,037 $ 508,532

Inventories

Inventories	3 Months Ended
	Mar. 31, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: March 31, December 31, Finished products $ 298,236 $ 253,338 Feedstock, additives and chemicals 103,837 106,435 Materials and supplies 76,583 74,287 Inventories $ 478,656 $ 434,060

Property, Plant and Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment As of March 31, 2016 , the Company had property, plant and equipment, net totaling $3,114,821 . The Company assesses these assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, including when negative conditions such as significant current or projected operating losses exist. Other factors considered by the Company when determining if an impairment assessment is necessary include, but are not limited to, significant changes or projected changes in supply and demand fundamentals (which would have a negative impact on operating rates or margins), new technological developments, new competitors with significant raw material or other cost advantages, adverse changes associated with the U.S. and world economies and uncertainties associated with governmental actions. 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. Depreciation expense on property, plant and equipment of $56,041 and $49,658 is included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2016 and 2015 , respectively.

Other Assets

Other Assets	3 Months Ended
	Mar. 31, 2016
Other Assets [Abstract]
Other Assets	Other Assets Amortization expense on intangible and other assets of $9,770 and $9,361 is included in the consolidated statements of operations for the three months ended March 31, 2016 and 2015 , respectively. Goodwill Goodwill for the Olefins segment was $29,990 at March 31, 2016 and December 31, 2015 . Goodwill for the Vinyls segment was $32,026 at March 31, 2016 and December 31, 2015 . There were no changes in the carrying amount of goodwill for either operating segment for the three months ended March 31, 2016 .

Accounts and Notes Payable

Accounts and Notes Payable	3 Months Ended
	Mar. 31, 2016
Accounts and Notes Payable [Abstract]
Accounts and Notes Payable	Accounts and Notes Payable Accounts and notes payable consist of the following: March 31, December 31, Accounts payable $ 256,351 $ 229,219 Notes payable to banks 1,033 6,110 Accounts and notes payable $ 257,384 $ 235,329

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt The Company adopted an accounting standards update to simplify the presentation of debt issuance costs effective January 1, 2016. The standard requires, on a retrospective basis, all costs incurred to issue debt, excluding line-of-credit arrangements, to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability. As a result, Other assets, net—Deferred charges and other assets, net and Long-term debt on the consolidated balance sheet as of December 31, 2015 have been adjusted to $167,417 and $758,148 , respectively, from the originally reported $173,384 and $764,115 , respectively, to reflect the retrospective application of the new accounting guidance. Long-term debt consists of the following: March 31, 2016 December 31, 2015 Principal Amount Unamortized Discount and Debt Issuance Costs Net Long-term Debt Principal Unamortized and Debt Net 3.60% senior notes due 2022 $ 250,000 $ (2,147 ) $ 247,853 $ 250,000 $ (2,232 ) $ 247,768 6 ½% senior notes due 2029 100,000 (971 ) 99,029 100,000 (989 ) 99,011 6 ¾% senior notes due 2032 250,000 (1,972 ) 248,028 250,000 (2,002 ) 247,998 6 ½% senior notes due 2035 (the "6 ½% GO Zone Senior Notes Due 2035") 89,000 (873 ) 88,127 89,000 (884 ) 88,116 6 ½% senior notes due 2035 (the "6 ½% IKE Zone Senior Notes Due 2035") 65,000 (626 ) 64,374 65,000 (634 ) 64,366 Loan related to tax-exempt waste disposal revenue bonds due 2027 10,889 — 10,889 10,889 — 10,889 Long-term debt, net $ 764,889 $ (6,589 ) $ 758,300 $ 764,889 $ (6,741 ) $ 758,148 Revolving Credit Facility The Company has a $400,000 senior secured revolving credit facility. The facility includes a provision permitting the Company to increase the size of the facility, up to four times, in increments of at least $25,000 each (up to a maximum of $200,000 ) under certain circumstances if the lenders agree to commit to such an increase. At March 31, 2016 , the Company had no borrowings outstanding under the revolving credit facility. Any borrowings under the facility will bear interest at either LIBOR plus a spread ranging from 1.25% to 1.75% , provided that so long as the Company is rated investment grade, the margin for LIBOR loans will not exceed 1.50% , or a base rate plus a spread ranging from 0.00% to 0.50% . The revolving credit facility also requires an unused commitment fee of 0.25% per annum. All interest rates under the facility are subject to monthly grid pricing adjustments based on prior month average daily loan availability. The revolving credit facility matures on July 17, 2019. As of March 31, 2016 , the Company had outstanding letters of credit totaling $30,445 and borrowing availability of $354,821 under the revolving credit facility.

Stockholders Equity

Stockholders Equity	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Changes in stockholders' equity for the three months ended March 31, 2016 and 2015 were as follows: Common Stock Common Stock, Held in Treasury Additional Paid-in Capital Retained Earnings Accumulated Other Comprehensive Income (Loss) Noncontrolling Interests Total Balances at December 31, 2015 $ 1,347 $ (258,312 ) $ 542,148 $ 3,109,987 $ (129,292 ) $ 296,053 $ 3,561,931 Net income — — — 123,128 — 5,808 128,936 Other comprehensive income, net of income taxes: Pension and other post- retirement benefits liability — — — — 206 — 206 Foreign currency translation adjustments — — — — 22,805 — 22,805 Net unrealized holding gains on investments — — — — 15,618 — 15,618 Shares issued—stock- based compensation — 1,853 (1,831 ) — — — 22 Stock-based compensation, net of tax on stock options exercised — — 2,569 — — — 2,569 Dividends paid — — — (23,700 ) — — (23,700 ) Distributions to noncontrolling interests — — — — — (3,985 ) (3,985 ) Balances at March 31, 2016 $ 1,347 $ (256,459 ) $ 542,886 $ 3,209,415 $ (90,663 ) $ 297,876 $ 3,704,402 Common Stock Common Stock, Held in Treasury Additional Paid-in Capital Retained Earnings Accumulated Other Comprehensive Income (Loss) Noncontrolling Interests Total Balances at December 31, 2014 $ 1,347 $ (96,372 ) $ 530,441 $ 2,555,528 $ (79,433 ) $ 290,377 $ 3,201,888 Net income — — — 146,342 — 4,065 150,407 Other comprehensive income (loss), net of income taxes Pension and other post- retirement benefits liability — — — — 427 — 427 Foreign currency translation adjustments — — — — (59,698 ) — (59,698 ) Net unrealized holding gains on investments — — — — 1,042 — 1,042 Common stock repurchased — (2,000 ) — — — — (2,000 ) Shares issued—stock- based compensation — 97 60 — — — 157 Stock-based compensation, net of tax on stock options exercised — — 4,041 — — — 4,041 Dividends paid — — — (21,964 ) — — (21,964 ) Distributions to noncontrolling interests — — — — — (3,558 ) (3,558 ) Balances at March 31, 2015 $ 1,347 $ (98,275 ) $ 534,542 $ 2,679,906 $ (137,662 ) $ 290,884 $ 3,270,742 Accumulated Other Comprehensive Loss Changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2016 and 2015 were as follows: Benefits Liability, Net of Tax Cumulative Foreign Currency Exchange Net Unrealized Holding (Losses) Gains on Investments, Net of Tax Total Balances at December 31, 2015 $ (8,607 ) $ (115,690 ) $ (4,995 ) $ (129,292 ) Other comprehensive income before reclassifications — 22,805 15,651 38,456 Amounts reclassified from accumulated other comprehensive loss (income) 206 — (33 ) 173 Net other comprehensive income for the period 206 22,805 15,618 38,629 Balances at March 31, 2016 $ (8,401 ) $ (92,885 ) $ 10,623 $ (90,663 ) Benefits Liability, Net of Tax Cumulative Foreign Currency Exchange Net Unrealized Holding Gains on Investments, Net of Tax Total Balances at December 31, 2014 $ (23,442 ) $ (56,224 ) $ 233 $ (79,433 ) Other comprehensive (loss) income before reclassifications — (59,698 ) 1,042 (58,656 ) Amounts reclassified from accumulated other comprehensive loss 427 — — 427 Net other comprehensive income (loss) for the period 427 (59,698 ) 1,042 (58,229 ) Balances at March 31, 2015 $ (23,015 ) $ (115,922 ) $ 1,275 $ (137,662 ) 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 for the three months ended March 31, 2016 and 2015 : Details about Accumulated Other Comprehensive Income (Loss) Components Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations Three Months Ended March 31, 2016 2015 Amortization of pension and other post-retirement items Net loss (1) $ (334 ) $ (652 ) Provision for income taxes 128 225 (206 ) (427 ) Net unrealized gains on available-for-sale investments Realized gain on available-for-sale investments Other income, net 52 — Provision for income taxes (19 ) — 33 — Total reclassifications for the period $ (173 ) $ (427 ) _____________ (1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 11 (Employee Benefits) to the financial statements included in the 2015 Form 10-K.

Pension and Post-Retirement Ben

Pension and Post-Retirement Benefit Costs	3 Months Ended
	Mar. 31, 2016
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Pension and Post-Retirement Benefit Costs	Pension and Post-Retirement Benefit Costs Defined Benefit Plans Components of net periodic benefit cost for the Company's pension plans are as follows: Three Months Ended March 31, 2016 2015 U.S. Plans Non-U.S. Plans U.S. Plans Non-U.S. Plans Service cost $ — $ 323 $ 28 $ 422 Interest cost 567 568 544 535 Expected return on plan assets (802 ) — (819 ) — Amortization of net loss 303 — 290 266 Net periodic benefit cost $ 68 $ 891 $ 43 $ 1,223 The Company made no contribution to the U.S. salaried pension plan in the first three months of 2016 and 2015 . The Company made no contribution to the U.S. wage pension plan in the first three months of 2016 . The Company contributed $112 to the U.S. wage pension plan in the first three months of 2015 . 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 $900 each for both the salaried and wage pension plans for the fiscal year ending December 31, 2016 . Other Post-retirement Benefits Components of net periodic benefit cost for the Company's other post-retirement benefits are as follows: Three Months Ended March 31, 2016 2015 U.S. Plans U.S. Plans Service cost $ 5 $ 6 Interest cost 145 149 Amortization of net loss 31 96 Net periodic benefit cost $ 181 $ 251

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	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). Total stock-based compensation expense related to the 2013 Plan was $2,303 and $2,340 for the three months ended March 31, 2016 and 2015 , respectively.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Commodity Risk Management The Company uses derivative instruments to reduce price volatility risk on raw materials and products as a substantial portion of its raw materials and products are commodities whose prices fluctuate as market supply and demand fundamentals change. Business strategies to protect against such instability include ethylene product feedstock flexibility and moving downstream into the olefins and vinyls products where pricing is more stable. The Company does not use derivative instruments to engage in speculative activities. Gains and losses from changes in the fair value of derivative instruments that are not designated as hedging instruments were included in gross profit in the consolidated statements of operations for the three months ended March 31, 2016 and 2015 . The exposure on commodity derivatives used for price risk management includes the risk that the counterparty will not pay if the market declines below the established fixed price. In such case, the Company would lose the benefit of the derivative differential on the volume of the commodities covered. In any event, the Company would continue to receive the market price on the actual volume hedged. The Company also bears the risk that it could lose the benefit of market improvements over the fixed derivative price for the term and volume of the derivative instruments (as such improvements would accrue to the benefit of the counterparty). The fair values of derivative instruments in the Company's consolidated balance sheets were as follows: Derivative Assets Balance Sheet Location Fair Value as of March 31, December 31, Not designated as hedging instruments Commodity forward contracts Accounts receivable, net $ 4,239 $ 3,465 Commodity forward contracts Deferred charges and other assets, net 1,716 2,088 Total derivative assets $ 5,955 $ 5,553 Derivative Liabilities Balance Sheet Location Fair Value as of March 31, December 31, Not designated as hedging instruments Commodity forward contracts Accrued liabilities $ 7,730 $ 9,325 Commodity forward contracts Other liabilities 9,137 12,437 Total derivative liabilities $ 16,867 $ 21,762 The impact of derivative instruments that have not been designated as hedges on the Company's consolidated statements of operations were as follows: Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Ended March 31, 2016 2015 Commodity forward contracts Gross profit $ 4,057 $ 4,241 See Note 13 for the fair value of the Company's derivative instruments. Disclosure about Offsetting Asset and Liability Derivatives Certain of the Company's derivative instruments are executed under an International Swaps and Derivatives Association ("ISDA") Master Agreement, which permits the Company and a counterparty to aggregate the amounts owed by each party under multiple transactions and replace them with a single net amount payable by one party to the other. The following tables present the Company's derivative assets and derivative liabilities reported on the consolidated balance sheets and derivative assets and derivative liabilities subject to enforceable master netting arrangements. Derivative Assets as of March 31, December 31, Derivative assets subject to enforceable master netting arrangements $ 340 $ — Derivative assets not subject to enforceable master netting arrangements 513 462 Total derivative assets $ 853 $ 462 March 31, 2016 December 31, 2015 Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Assets Presented in the Consolidated Balance Sheet Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Assets Presented in the Consolidated Balance Sheet Commodity forward contracts $ 5,442 $ (5,102 ) $ 340 $ 5,091 $ (5,091 ) $ — March 31, 2016 December 31, 2015 Derivative Assets by Counterparty Net Amounts of Assets Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Net Amounts of Assets Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Counterparty A $ 340 $ — $ 340 $ — $ — $ — Derivative Liabilities as of March 31, December 31, Derivative liabilities subject to enforceable master netting arrangements $ 3,278 $ 5,803 Derivative liabilities not subject to enforceable master netting arrangements 8,487 10,868 Total derivative liabilities $ 11,765 $ 16,671 March 31, 2016 December 31, 2015 Offsetting of Derivative Liabilities Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Commodity forward contracts $ 8,380 $ (5,102 ) $ 3,278 $ 10,894 $ (5,091 ) $ 5,803 March 31, 2016 December 31, 2015 Derivative Liabilities by Counterparty Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Counterparty A $ 3,149 $ — $ 3,149 $ 5,564 $ — $ 5,564 Counterparty B 129 — 129 239 — 239 Total $ 3,278 $ — $ 3,278 $ 5,803 $ — $ 5,803

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company reports certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). 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 following tables summarize, by level within the fair value hierarchy, the Company's assets and liabilities that were accounted for at fair value on a recurring basis: March 31, 2016 Level 1 Level 2 Total Derivative instruments Risk management assets—Commodity forward contracts $ 5,896 $ 59 $ 5,955 Risk management liabilities—Commodity forward contracts (11,983 ) (4,884 ) (16,867 ) Marketable securities Available-for-sale securities 75,114 525,008 600,122 December 31, 2015 Level 1 Level 2 Total Derivative instruments Risk management assets—Commodity forward contracts $ 5,553 $ — $ 5,553 Risk management liabilities—Commodity forward contracts (11,648 ) (10,114 ) (21,762 ) Marketable securities Available-for-sale securities 48,081 520,144 568,225 The Level 2 measurements for the Company's commodity contracts are derived using forward curves supplied by industry-recognized and unrelated third-party services. The Level 2 measurements for the Company's available-for-sale securities are derived using market-based pricing provided by unrelated third-party services. There were no transfers in or out of Levels 1 and 2 of the fair value hierarchy for the three months ended March 31, 2016 and 2015 . In addition to the financial assets and liabilities above, the Company has other financial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts and notes 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 and notes 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 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. March 31, 2016 December 31, 2015 Carrying Value Fair Value Carrying Value Fair Value 3.60% senior notes due 2022 $ 247,853 $ 245,500 $ 247,768 $ 244,828 6 ½% senior notes due 2029 99,029 115,436 99,011 117,153 6 ¾% senior notes due 2032 248,028 267,593 247,998 268,490 6 ½% GO Zone Senior Notes Due 2035 88,127 106,167 88,116 106,491 6 ½% IKE Zone Senior Notes Due 2035 64,374 77,538 64,366 76,741 Loan related to tax-exempt waste disposal revenue bonds due 2027 10,889 10,889 10,889 10,889 The carrying values of the Company's long-term debt as of December 31, 2015 have been adjusted to reflect the retrospective application of the accounting standards update on simplifying the presentation of debt issuance costs discussed in Note 8.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company elected to early adopt an accounting standards update requiring the noncurrent classification of all deferred tax assets and liabilities, along with any related valuation allowance, effective January 1, 2016. As a result, the Company's deferred tax assets and liabilities have been classified, by jurisdiction, as a net noncurrent deferred tax asset or liability on the consolidated balance sheet. Consistent with the prospective application of this accounting standard, prior period comparative information was not adjusted. The effective income tax rate for the three months ended March 31, 2016 was at the U.S. federal statutory rate of 35.0% primarily due to the benefit of state tax credits, the domestic manufacturing deduction, income attributable to noncontrolling interests and the foreign earnings rate differential, offset by state income taxes. The effective income tax rate was 34.3% for the three months ended March 31, 2015 . The effective income tax rate for the 2015 period was below the U.S. federal statutory rate of 35.0% primarily due to the benefit of state tax credits, the domestic manufacturing deduction, income attributable to noncontrolling interests and the foreign earnings rate differential, partially offset by state income taxes. There were no unrecognized tax benefits for the three months ended March 31, 2016 . The Company recognizes penalties and interest accrued related to unrecognized tax benefits in income tax expense. As of March 31, 2016 , the Company had no accrued interest and penalties related to uncertain tax positions. 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 2010. The Company intends to reinvest its foreign subsidiaries' undistributed earnings, which are estimated to be $115,000 for the year ending December 31, 2016 , indefinitely outside of the U.S. to support its foreign operations. The estimated deferred tax liability associated with such foreign undistributed earnings is expected to be immaterial for the year ending December 31, 2016 , taking into account the availability of foreign tax credits under current law to reduce the resulting U.S. income tax liability.

Earnings per Share

Earnings per Share	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The Company has unvested shares of restricted stock and 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. Three Months Ended March 31, 2016 2015 Net income attributable to Westlake Chemical Corporation $ 123,128 $ 146,342 Less: Net income attributable to participating securities (549 ) (200 ) Net income attributable to common shareholders $ 122,579 $ 146,142 The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations: Three Months Ended March 31, 2016 2015 Weighted average common shares—basic 130,189,964 132,714,566 Plus incremental shares from: Assumed exercise of options 410,550 490,740 Weighted average common shares—diluted 130,600,514 133,205,306 Earnings per common share attributable to Westlake Chemical Corporation: Basic $ 0.94 $ 1.10 Diluted $ 0.94 $ 1.10 Excluded from the computation of diluted earnings per share are options to purchase 555,948 and 241,312 shares of common stock for the three months ended March 31, 2016 and 2015 , respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive.

Supplemental Information

Supplemental Information	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Information	Supplemental Information Accrued Liabilities Accrued liabilities were $248,777 and $287,313 at March 31, 2016 and December 31, 2015 , respectively. Accrued capital expenditures and accrued incentive compensation, which are components of accrued liabilities, were $32,037 and $25,680 at March 31, 2016 , respectively, and $21,597 and $41,168 at December 31, 2015 , respectively. No other component of accrued liabilities was more than five percent of total current liabilities. Other Liabilities Other liabilities were $145,786 and $150,961 at March 31, 2016 and December 31, 2015 , respectively. Non-current pension obligation, which is a component of other liabilities, was $107,413 and $106,250 at March 31, 2016 and December 31, 2015 , respectively. No other component of other liabilities was more than five percent of total liabilities.

Insurance Recovery

Insurance Recovery	3 Months Ended
	Mar. 31, 2016
Insurance Recovery [Abstract]
Insurance Recovery	Insurance Recovery During the second and third quarters of 2015, the Company's production rates and operating costs at its Knapsack, Germany and Cologne, Germany facilities were negatively impacted due to an interruption of feedstock supply as a result of a fire at a third-party supplier's ethylene production facility. During the three months ended March 31, 2016 , the Company received a final insurance recovery of approximately $2,670 related to business interruption costs. The insurance recovery is included in cost of sales in the consolidated statement of operations. The Company had received and recognized approximately $7,809 as a partial insurance recovery during the year ended December 31, 2015 .

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company is subject to environmental laws and regulations that can impose civil and criminal sanctions and that may require it to mitigate the effects of contamination caused by the release or disposal of hazardous substances into the environment. Under one law, the U.S. Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), an owner or operator of property may be held strictly liable for remediating contamination without regard to whether that person caused the contamination, and without regard to whether the practices that resulted in the contamination were legal at the time they occurred. Because several of the Company's production sites have a history of industrial use, it is impossible to predict precisely what effect these legal requirements will have on the Company. European Regulations. Under the Industrial Emission Directive ("IED"), European Union member state governments are expected to adopt rules and implement environmental permitting programs relating to air, water and waste for industrial facilities. In this context, concepts such as BAT ("best available technique") are being explored. Future implementation of these concepts may result in technical modifications in the Company's European facilities. In addition, under the Environmental Liability Directive, European Union member states can require the remediation of soil and groundwater contamination in certain circumstances, under the "polluter pays principle." The Company is unable to predict the impact these requirements and concepts may have on its future costs of compliance. Contract Disputes with Goodrich and PolyOne. In connection with the 1990 and 1997 acquisitions of the Goodrich Corporation ("Goodrich") chemical manufacturing facility in Calvert City, Kentucky, Goodrich agreed to indemnify the Company for any liabilities related to preexisting contamination at the site. 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 site, which does not include the Company's nearby polyvinyl chloride ("PVC") facility, had been extensively contaminated under Goodrich's operations. In 1993, Goodrich spun off the predecessor of PolyOne Corporation ("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; (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; and (3) the Company and PolyOne would negotiate a new environmental remediation utilities and services agreement to cover the Company's provision to, or on behalf of, PolyOne of certain environmental remediation services at the site. The current environmental remediation activities at the Calvert City site do not have a specified termination date but are expected to last for the foreseeable future. The costs incurred by the Company that have been invoiced to PolyOne to provide the environmental remediation services were $2,210 in 2015 . By letter dated March 16, 2010, PolyOne notified the Company that it was initiating an arbitration proceeding under the settlement agreement. In this proceeding, PolyOne sought to readjust the percentage allocation of costs and to recover approximately $1,400 from the Company in reimbursement of previously paid remediation costs. In December 2015, the arbitration panel dismissed the proceeding with prejudice. In a separate proceeding in Ohio state court, the Company is seeking certain insurance documents from PolyOne. State Administrative Proceedings. There are several administrative proceedings in Kentucky involving the Company, Goodrich and PolyOne related to the same manufacturing site in Calvert City. In 2003, the Kentucky Environmental and Public Protection Cabinet (the "Cabinet") re-issued Goodrich's Resource Conservation and Recovery Act ("RCRA") permit which requires Goodrich to remediate contamination at the Calvert City manufacturing site. Both Goodrich and PolyOne challenged various terms of the permit in an attempt to shift Goodrich's clean-up obligations under the permit to the Company. The Company intervened in the proceedings. The Cabinet has suspended all corrective action under the RCRA permit in deference to a remedial investigation and feasibility study ("RIFS") being conducted, under the auspices of the U.S. Environmental Protection Agency ("EPA"), pursuant to an Administrative Settlement Agreement ("AOC"), which became effective on December 9, 2009. See "Federal Administrative Proceedings" below. The proceedings have been postponed. Periodic status conferences will be held to evaluate whether additional proceedings will be required. Federal Administrative Proceedings. In May 2009, the Cabinet sent a letter to the EPA requesting the EPA's assistance in addressing contamination at the Calvert City site under CERCLA. In its response to the Cabinet also in May 2009, the EPA stated that it concurred with the Cabinet's request and would incorporate work previously conducted under the Cabinet's RCRA authority into the EPA's cleanup efforts under CERCLA. Since 1983, the EPA has been addressing contamination at an abandoned landfill adjacent to the Company's plant which had been operated by Goodrich and which was being remediated pursuant to CERCLA. The EPA has directed Goodrich and PolyOne to conduct additional investigation activities at the landfill and at the Company's plant. In June 2009, the EPA notified the Company that the Company may have potential liability under section 107(a) of CERCLA at its plant site. Liability under section 107(a) of CERCLA is strict and joint and several. The EPA also identified Goodrich and PolyOne, among others, as potentially responsible parties at the plant site. The Company negotiated, in conjunction with the other potentially responsible parties, an AOC and an order to conduct a RIFS. On July 12, 2013, the parties submitted separate draft RIFS reports to the EPA. The EPA has hired a contractor to complete the remedial investigation report. Monetary Relief . Except as noted above with respect to the settlement of the contract litigation among the Company, Goodrich and PolyOne, none of the court, the Cabinet nor the EPA has established any allocation of the costs of remediation among the various parties that are involved in the judicial and administrative proceedings discussed above. At this time, the Company is not able to estimate the loss or reasonable possible loss, if any, on the Company's financial statements that could result from the resolution of these proceedings. Any cash expenditures that the Company might incur in the future with respect to the remediation of contamination at the site 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. Potential Flare Modifications . For several years, the EPA has been conducting an enforcement initiative against petroleum refineries and petrochemical plants with respect to emissions from flares. A number of companies have entered into consent agreements with the EPA requiring both modifications to reduce flare emissions and the installation of additional equipment to better track flare operations and emissions. On April 21, 2014, the Company received a Clean Air Act Section 114 Information Request from the EPA which sought information regarding flares at the Calvert City and Lake Charles, Louisiana facilities. The EPA has informed the Company that the information provided leads the EPA to believe that some of the flares are out of compliance with applicable standards. The EPA has demanded that the Company conduct additional flare sampling and provide supplemental information. The Company is currently in negotiations with the EPA regarding these demands. The EPA has indicated that it is seeking a consent decree that would obligate the Company to take corrective actions relating to the alleged noncompliance. The Company has not agreed that any flares are out of compliance or that any corrective actions are warranted. Depending on the outcome of the Company's negotiations with the EPA, additional controls on emissions from its flares may be required and these could result in increased capital and operating costs. Louisiana Notice of Violations. The Louisiana Department of Environmental Quality ("LDEQ") has issued notices of violations ("NOVs") regarding the Company's assets for various air compliance issues. The Company is working with LDEQ to settle these claims, and a global settlement of all claims is being discussed. The Company has reached a verbal agreement with the LDEQ to settle certain of the NOVs in two separate settlements for a combined $192 in civil penalties. The Company does not believe that any settlements for the remaining NOVs will have a material adverse effect on the Company's financial condition, results of operations or cash flows. In addition to the matters described above, the Company is involved in various legal proceedings incidental to the conduct of its business. The Company does not believe that any of these legal proceedings will have a material adverse effect on its financial condition, results of operations or cash flows.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Segment 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. Three Months Ended March 31, 2016 2015 Net external sales Olefins Polyethylene $ 346,032 $ 409,432 Styrene, feedstock and other 84,988 173,645 Total Olefins 431,020 583,077 Vinyls PVC, caustic soda and other 430,902 416,988 Building products 113,265 103,466 Total Vinyls 544,167 520,454 $ 975,187 $ 1,103,531 Intersegment sales Olefins $ 27,949 $ 23,462 Vinyls 364 370 $ 28,313 $ 23,832 Income (loss) from operations Olefins $ 149,235 $ 191,103 Vinyls 62,116 47,086 Corporate and other (9,075 ) (8,909 ) $ 202,276 $ 229,280 Depreciation and amortization Olefins $ 28,697 $ 26,939 Vinyls 36,287 31,584 Corporate and other 730 118 $ 65,714 $ 58,641 Three Months Ended March 31, 2016 2015 Other income (expense), net Olefins $ 1,513 $ 2,552 Vinyls (1,519 ) 5,503 Corporate and other 2,651 1,041 $ 2,645 $ 9,096 Provision for (benefit from) income taxes Olefins $ 52,533 $ 66,457 Vinyls 17,270 12,805 Corporate and other (503 ) (884 ) $ 69,300 $ 78,378 Capital expenditures Olefins $ 95,152 $ 55,300 Vinyls 40,256 36,855 Corporate and other 920 3,667 $ 136,328 $ 95,822 A reconciliation of total segment income from operations to consolidated income before income taxes is as follows: Three Months Ended March 31, 2016 2015 Income from operations $ 202,276 $ 229,280 Interest expense (6,685 ) (9,591 ) Other income, net 2,645 9,096 Income before income taxes $ 198,236 $ 228,785 March 31, December 31, Total assets Olefins $ 1,971,395 $ 1,869,888 Vinyls 2,704,560 2,638,833 Corporate and other 1,048,446 1,060,564 $ 5,724,401 $ 5,569,285

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Subsequent events were evaluated through the date on which the financial statements were issued.

Guarantor Disclosures

Guarantor Disclosures	3 Months Ended
	Mar. 31, 2016
Guarantees [Abstract]
Guarantor Disclosures	Guarantor Disclosures The Company's payment obligations under the 3.60% senior notes due 2022 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 the 3.60% senior notes due 2022 in excess of $5,000 (the "Guarantor Subsidiaries"). Except for Westlake Chemical OpCo LP ("OpCo"), which is less than 100% owned, each Guarantor Subsidiary is 100% owned by Westlake Chemical Corporation (the " 100% Owned Guarantor Subsidiaries"). The August 4, 2014 initial public offering of Westlake Chemical Partners LP ("Westlake Partners") resulted in OpCo ceasing to be a 100% owned subsidiary of the Company. These guarantees are the joint and several obligations of the Guarantor Subsidiaries. The following unaudited condensed consolidating financial information presents the financial condition, results of operations and cash flows of Westlake Chemical Corporation, the 100% owned Guarantor Subsidiaries, OpCo and the remaining subsidiaries that do not guarantee the 3.60% senior notes due 2022 (the "Non-Guarantor Subsidiaries"), together with consolidating eliminations necessary to present the Company's results on a consolidated basis.

Basis of Financial Statements (

Basis of Financial Statements (Policies)	3 Months Ended
	Mar. 31, 2016
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, 2015 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, 2015 (the " 2015 Form 10-K"), filed with the SEC on February 24, 2016 . 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, 2015 . 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 March 31, 2016 , its results of operations for the three months ended March 31, 2016 and 2015 and the changes in its cash position for the three months ended March 31, 2016 and 2015 . 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, 2016 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 March 2016, the FASB issued additional authoritative guidance to provide clarification on principal versus agent considerations included within the new revenue recognition standard. The accounting standard (including the clarification guidance issued in March 2016) will 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. Recognition and Measurement of Financial Assets and Financial Liabilities 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. 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. Leases 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. Stock Compensation 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. The accounting standard is effective for reporting periods beginning after December 15, 2016. 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 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 is effective for annual periods beginning after December 15, 2015. The Company adopted this accounting standard effective January 1, 2016 and the adoption did not have an impact on the Company's consolidated financial position, results of operations and cash flows. Intangibles—Goodwill and Other—Internal use software In April 2015, the FASB issued an accounting standards update to provide clarification on accounting for cloud computing arrangements which include a software license. The accounting standard is effective for annual periods beginning after December 15, 2015. The Company adopted this accounting standard, to be applied prospectively, effective January 1, 2016. Consistent with the prospective application of this accounting standard, prior period comparative information was not adjusted. The adoption did not have a material 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 is effective for reporting periods beginning after December 15, 2015. The Company adopted this accounting standard effective January 1, 2016. As a result, Other assets, net—Deferred charges and other assets, net and Long-term debt on the consolidated balance sheet as of December 31, 2015 have been adjusted to $167,417 and $758,148 , respectively, from the originally reported $173,384 and $764,115 , respectively, to reflect the retrospective application of the new accounting guidance. The adoption of this accounting standard did not have an impact on the Company's 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 is effective for reporting periods beginning after December 15, 2015. The Company adopted this accounting standard effective January 1, 2016 and the adoption did not have an impact on the Company's consolidated financial position, results of operations and cash flows. Balance Sheet Classification of Deferred Taxes In November 2015, the FASB issued an accounting standards update that requires all deferred tax assets and liabilities, along with any related valuation allowance, to be classified as noncurrent on the balance sheet. As a result, each jurisdiction will now only have one net noncurrent deferred tax asset or liability. The new guidance does not change the existing requirement that only permits offsetting within a jurisdiction. The accounting standard is required to be adopted for reporting periods beginning after December 15, 2016; however, early adoption of this standard is permitted. The Company elected to early adopt this accounting standard, to be applied prospectively, effective January 1, 2016. Consistent with the prospective application of this accounting standard, prior period comparative information was not adjusted. The early adoption of this accounting standard did not have an impact on the Company's results of operations and cash flows.

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Investments in available-for-sale securities were classified as follows: March 31, December 31, Current $ 525,008 $ 520,144 Non-current 75,114 48,081 Total available-for-sale securities $ 600,122 $ 568,225
Available-for-sale Securities	The cost, gross unrealized gains, gross unrealized losses and fair value of the Company's available-for-sale securities were as follows: March 31, 2016 Cost Gross Gross (1) Fair Value Debt securities Corporate bonds $ 341,856 $ 1,411 $ (185 ) $ 343,082 U.S. government debt (2) 125,114 425 (9 ) 125,530 Asset-backed securities 56,289 120 (13 ) 56,396 Equity securities 60,283 14,927 (96 ) 75,114 Total available-for-sale securities $ 583,542 $ 16,883 $ (303 ) $ 600,122 December 31, 2015 Cost Gross Gross (1) Fair Value Debt securities Corporate bonds $ 336,665 $ 55 $ (1,076 ) $ 335,644 U.S. government debt (2) 135,226 2 (374 ) 134,854 Asset-backed securities 49,759 2 (115 ) 49,646 Equity securities 54,371 466 (6,756 ) 48,081 Total available-for-sale securities $ 576,021 $ 525 $ (8,321 ) $ 568,225 _____________ (1) All unrealized loss positions were held at a loss for less than 12 months. (2) U.S. Treasury obligations, U.S. government agency obligations and U.S government agency mortgage-backed securities.
Schedule of Realized Gain (Loss)	Three Months Ended March 31, 2016 Proceeds from sales and maturities of securities $ 26,859 Gross realized gains 61 Gross realized losses (9 )

Accounts Receivable (Tables)

Accounts Receivable (Tables)	3 Months Ended
	Mar. 31, 2016
Accounts Receivable, Net [Abstract]
Schedule Of Accounts Receivable	Accounts receivable consist of the following: March 31, December 31, Trade customers $ 465,697 $ 438,538 Allowance for doubtful accounts (14,321 ) (14,095 ) 451,376 424,443 Federal and state taxes 81,255 60,748 Other 16,406 23,341 Accounts receivable, net $ 549,037 $ 508,532

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2016
Inventory Disclosure [Abstract]
Schedule Of Inventory	Inventories consist of the following: March 31, December 31, Finished products $ 298,236 $ 253,338 Feedstock, additives and chemicals 103,837 106,435 Materials and supplies 76,583 74,287 Inventories $ 478,656 $ 434,060

Accounts and Notes Payable (Tab

Accounts and Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2016
Accounts and Notes Payable [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	March 31, December 31, Accounts payable $ 256,351 $ 229,219 Notes payable to banks 1,033 6,110 Accounts and notes payable $ 257,384 $ 235,329

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	March 31, 2016 December 31, 2015 Principal Amount Unamortized Discount and Debt Issuance Costs Net Long-term Debt Principal Unamortized and Debt Net 3.60% senior notes due 2022 $ 250,000 $ (2,147 ) $ 247,853 $ 250,000 $ (2,232 ) $ 247,768 6 ½% senior notes due 2029 100,000 (971 ) 99,029 100,000 (989 ) 99,011 6 ¾% senior notes due 2032 250,000 (1,972 ) 248,028 250,000 (2,002 ) 247,998 6 ½% senior notes due 2035 (the "6 ½% GO Zone Senior Notes Due 2035") 89,000 (873 ) 88,127 89,000 (884 ) 88,116 6 ½% senior notes due 2035 (the "6 ½% IKE Zone Senior Notes Due 2035") 65,000 (626 ) 64,374 65,000 (634 ) 64,366 Loan related to tax-exempt waste disposal revenue bonds due 2027 10,889 — 10,889 10,889 — 10,889 Long-term debt, net $ 764,889 $ (6,589 ) $ 758,300 $ 764,889 $ (6,741 ) $ 758,148

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Schedule of Stockholders Equity	Changes in stockholders' equity for the three months ended March 31, 2016 and 2015 were as follows: Common Stock Common Stock, Held in Treasury Additional Paid-in Capital Retained Earnings Accumulated Other Comprehensive Income (Loss) Noncontrolling Interests Total Balances at December 31, 2015 $ 1,347 $ (258,312 ) $ 542,148 $ 3,109,987 $ (129,292 ) $ 296,053 $ 3,561,931 Net income — — — 123,128 — 5,808 128,936 Other comprehensive income, net of income taxes: Pension and other post- retirement benefits liability — — — — 206 — 206 Foreign currency translation adjustments — — — — 22,805 — 22,805 Net unrealized holding gains on investments — — — — 15,618 — 15,618 Shares issued—stock- based compensation — 1,853 (1,831 ) — — — 22 Stock-based compensation, net of tax on stock options exercised — — 2,569 — — — 2,569 Dividends paid — — — (23,700 ) — — (23,700 ) Distributions to noncontrolling interests — — — — — (3,985 ) (3,985 ) Balances at March 31, 2016 $ 1,347 $ (256,459 ) $ 542,886 $ 3,209,415 $ (90,663 ) $ 297,876 $ 3,704,402 Common Stock Common Stock, Held in Treasury Additional Paid-in Capital Retained Earnings Accumulated Other Comprehensive Income (Loss) Noncontrolling Interests Total Balances at December 31, 2014 $ 1,347 $ (96,372 ) $ 530,441 $ 2,555,528 $ (79,433 ) $ 290,377 $ 3,201,888 Net income — — — 146,342 — 4,065 150,407 Other comprehensive income (loss), net of income taxes Pension and other post- retirement benefits liability — — — — 427 — 427 Foreign currency translation adjustments — — — — (59,698 ) — (59,698 ) Net unrealized holding gains on investments — — — — 1,042 — 1,042 Common stock repurchased — (2,000 ) — — — — (2,000 ) Shares issued—stock- based compensation — 97 60 — — — 157 Stock-based compensation, net of tax on stock options exercised — — 4,041 — — — 4,041 Dividends paid — — — (21,964 ) — — (21,964 ) Distributions to noncontrolling interests — — — — — (3,558 ) (3,558 ) Balances at March 31, 2015 $ 1,347 $ (98,275 ) $ 534,542 $ 2,679,906 $ (137,662 ) $ 290,884 $ 3,270,742
Schedule of Accumulated Other Comprehensive Income (Loss)	Changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2016 and 2015 were as follows: Benefits Liability, Net of Tax Cumulative Foreign Currency Exchange Net Unrealized Holding (Losses) Gains on Investments, Net of Tax Total Balances at December 31, 2015 $ (8,607 ) $ (115,690 ) $ (4,995 ) $ (129,292 ) Other comprehensive income before reclassifications — 22,805 15,651 38,456 Amounts reclassified from accumulated other comprehensive loss (income) 206 — (33 ) 173 Net other comprehensive income for the period 206 22,805 15,618 38,629 Balances at March 31, 2016 $ (8,401 ) $ (92,885 ) $ 10,623 $ (90,663 ) Benefits Liability, Net of Tax Cumulative Foreign Currency Exchange Net Unrealized Holding Gains on Investments, Net of Tax Total Balances at December 31, 2014 $ (23,442 ) $ (56,224 ) $ 233 $ (79,433 ) Other comprehensive (loss) income before reclassifications — (59,698 ) 1,042 (58,656 ) Amounts reclassified from accumulated other comprehensive loss 427 — — 427 Net other comprehensive income (loss) for the period 427 (59,698 ) 1,042 (58,229 ) Balances at March 31, 2015 $ (23,015 ) $ (115,922 ) $ 1,275 $ (137,662 )
Reclassification out of Accumulated Other Comprehensive Income (Loss)	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 for the three months ended March 31, 2016 and 2015 : Details about Accumulated Other Comprehensive Income (Loss) Components Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations Three Months Ended March 31, 2016 2015 Amortization of pension and other post-retirement items Net loss (1) $ (334 ) $ (652 ) Provision for income taxes 128 225 (206 ) (427 ) Net unrealized gains on available-for-sale investments Realized gain on available-for-sale investments Other income, net 52 — Provision for income taxes (19 ) — 33 — Total reclassifications for the period $ (173 ) $ (427 ) _____________ (1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 11 (Employee Benefits) to the financial statements included in the 2015 Form 10-K.

Pension and Post-Retirement B35

Pension and Post-Retirement Benefit Costs (Tables)	3 Months Ended
	Mar. 31, 2016
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Components of Net Periodic Benefit Cost	Components of net periodic benefit cost for the Company's pension plans are as follows: Three Months Ended March 31, 2016 2015 U.S. Plans Non-U.S. Plans U.S. Plans Non-U.S. Plans Service cost $ — $ 323 $ 28 $ 422 Interest cost 567 568 544 535 Expected return on plan assets (802 ) — (819 ) — Amortization of net loss 303 — 290 266 Net periodic benefit cost $ 68 $ 891 $ 43 $ 1,223 Components of net periodic benefit cost for the Company's other post-retirement benefits are as follows: Three Months Ended March 31, 2016 2015 U.S. Plans U.S. Plans Service cost $ 5 $ 6 Interest cost 145 149 Amortization of net loss 31 96 Net periodic benefit cost $ 181 $ 251

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Values of Derivatives Instruments in Consolidated Balance Sheets	The fair values of derivative instruments in the Company's consolidated balance sheets were as follows: Derivative Assets Balance Sheet Location Fair Value as of March 31, December 31, Not designated as hedging instruments Commodity forward contracts Accounts receivable, net $ 4,239 $ 3,465 Commodity forward contracts Deferred charges and other assets, net 1,716 2,088 Total derivative assets $ 5,955 $ 5,553 Derivative Liabilities Balance Sheet Location Fair Value as of March 31, December 31, Not designated as hedging instruments Commodity forward contracts Accrued liabilities $ 7,730 $ 9,325 Commodity forward contracts Other liabilities 9,137 12,437 Total derivative liabilities $ 16,867 $ 21,762
Impact of Derivative Instruments Not Designated as Fair Value Hedges	The impact of derivative instruments that have not been designated as hedges on the Company's consolidated statements of operations were as follows: Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Ended March 31, 2016 2015 Commodity forward contracts Gross profit $ 4,057 $ 4,241
Offsetting Assets	Derivative Assets as of March 31, December 31, Derivative assets subject to enforceable master netting arrangements $ 340 $ — Derivative assets not subject to enforceable master netting arrangements 513 462 Total derivative assets $ 853 $ 462 March 31, 2016 December 31, 2015 Offsetting of Derivative Assets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Assets Presented in the Consolidated Balance Sheet Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Assets Presented in the Consolidated Balance Sheet Commodity forward contracts $ 5,442 $ (5,102 ) $ 340 $ 5,091 $ (5,091 ) $ — March 31, 2016 December 31, 2015 Derivative Assets by Counterparty Net Amounts of Assets Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Net Amounts of Assets Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Counterparty A $ 340 $ — $ 340 $ — $ — $ —
Offsetting Liabilities	Derivative Liabilities as of March 31, December 31, Derivative liabilities subject to enforceable master netting arrangements $ 3,278 $ 5,803 Derivative liabilities not subject to enforceable master netting arrangements 8,487 10,868 Total derivative liabilities $ 11,765 $ 16,671 March 31, 2016 December 31, 2015 Offsetting of Derivative Liabilities Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Balance Sheet Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Commodity forward contracts $ 8,380 $ (5,102 ) $ 3,278 $ 10,894 $ (5,091 ) $ 5,803 March 31, 2016 December 31, 2015 Derivative Liabilities by Counterparty Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Net Amounts of Liabilities Presented in the Consolidated Balance Sheet Gross Amounts Not Offset in the Consolidated Balance Sheet Net Amount Counterparty A $ 3,149 $ — $ 3,149 $ 5,564 $ — $ 5,564 Counterparty B 129 — 129 239 — 239 Total $ 3,278 $ — $ 3,278 $ 5,803 $ — $ 5,803

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Summary Of Assets And Liabilities Accounted At Fair Value On A Recurring Basis	The following tables summarize, by level within the fair value hierarchy, the Company's assets and liabilities that were accounted for at fair value on a recurring basis: March 31, 2016 Level 1 Level 2 Total Derivative instruments Risk management assets—Commodity forward contracts $ 5,896 $ 59 $ 5,955 Risk management liabilities—Commodity forward contracts (11,983 ) (4,884 ) (16,867 ) Marketable securities Available-for-sale securities 75,114 525,008 600,122 December 31, 2015 Level 1 Level 2 Total Derivative instruments Risk management assets—Commodity forward contracts $ 5,553 $ — $ 5,553 Risk management liabilities—Commodity forward contracts (11,648 ) (10,114 ) (21,762 ) Marketable securities Available-for-sale securities 48,081 520,144 568,225
Summary Of Carrying And Fair Values Of Long-Term Debt	The carrying and fair values of the Company's long-term debt 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. March 31, 2016 December 31, 2015 Carrying Value Fair Value Carrying Value Fair Value 3.60% senior notes due 2022 $ 247,853 $ 245,500 $ 247,768 $ 244,828 6 ½% senior notes due 2029 99,029 115,436 99,011 117,153 6 ¾% senior notes due 2032 248,028 267,593 247,998 268,490 6 ½% GO Zone Senior Notes Due 2035 88,127 106,167 88,116 106,491 6 ½% IKE Zone Senior Notes Due 2035 64,374 77,538 64,366 76,741 Loan related to tax-exempt waste disposal revenue bonds due 2027 10,889 10,889 10,889 10,889 The carrying values of the Company's long-term debt as of December 31, 2015 have been adjusted to reflect the retrospective application of the accounting standards update on simplifying the presentation of debt issuance costs discussed in Note 8.

Earnings per Share (Tables)

Earnings per Share (Tables)	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Schedule Of Net Income Attributable To Common Stockholders	Three Months Ended March 31, 2016 2015 Net income attributable to Westlake Chemical Corporation $ 123,128 $ 146,342 Less: Net income attributable to participating securities (549 ) (200 ) Net income attributable to common shareholders $ 122,579 $ 146,142
Reconciliation Of Denominator For Basic And Diluted Earnings Per Share	The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations: Three Months Ended March 31, 2016 2015 Weighted average common shares—basic 130,189,964 132,714,566 Plus incremental shares from: Assumed exercise of options 410,550 490,740 Weighted average common shares—diluted 130,600,514 133,205,306 Earnings per common share attributable to Westlake Chemical Corporation: Basic $ 0.94 $ 1.10 Diluted $ 0.94 $ 1.10

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Segment Reporting Information	Three Months Ended March 31, 2016 2015 Net external sales Olefins Polyethylene $ 346,032 $ 409,432 Styrene, feedstock and other 84,988 173,645 Total Olefins 431,020 583,077 Vinyls PVC, caustic soda and other 430,902 416,988 Building products 113,265 103,466 Total Vinyls 544,167 520,454 $ 975,187 $ 1,103,531 Intersegment sales Olefins $ 27,949 $ 23,462 Vinyls 364 370 $ 28,313 $ 23,832 Income (loss) from operations Olefins $ 149,235 $ 191,103 Vinyls 62,116 47,086 Corporate and other (9,075 ) (8,909 ) $ 202,276 $ 229,280 Depreciation and amortization Olefins $ 28,697 $ 26,939 Vinyls 36,287 31,584 Corporate and other 730 118 $ 65,714 $ 58,641 Three Months Ended March 31, 2016 2015 Other income (expense), net Olefins $ 1,513 $ 2,552 Vinyls (1,519 ) 5,503 Corporate and other 2,651 1,041 $ 2,645 $ 9,096 Provision for (benefit from) income taxes Olefins $ 52,533 $ 66,457 Vinyls 17,270 12,805 Corporate and other (503 ) (884 ) $ 69,300 $ 78,378 Capital expenditures Olefins $ 95,152 $ 55,300 Vinyls 40,256 36,855 Corporate and other 920 3,667 $ 136,328 $ 95,822
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: Three Months Ended March 31, 2016 2015 Income from operations $ 202,276 $ 229,280 Interest expense (6,685 ) (9,591 ) Other income, net 2,645 9,096 Income before income taxes $ 198,236 $ 228,785
Total Assets	March 31, December 31, Total assets Olefins $ 1,971,395 $ 1,869,888 Vinyls 2,704,560 2,638,833 Corporate and other 1,048,446 1,060,564 $ 5,724,401 $ 5,569,285

Guarantor Disclosures (Tables)

Guarantor Disclosures (Tables)	3 Months Ended
	Mar. 31, 2016
Guarantees [Abstract]
Condensed Consolidating Financial Information Balance Sheet	Condensed Consolidating Financial Information as of March 31, 2016 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 263,150 $ 1,164 $ 170,755 $ 179,907 $ — $ 614,976 Marketable securities 525,008 — — — — 525,008 Accounts receivable, net 11,705 2,205,593 62,109 133,547 (1,863,917 ) 549,037 Inventories — 363,470 2,590 112,596 — 478,656 Prepaid expenses and other current assets 2,373 16,525 157 8,605 (3,603 ) 24,057 Total current assets 802,236 2,586,752 235,611 434,655 (1,867,520 ) 2,191,734 Property, plant and equipment, net — 1,588,966 1,096,354 429,501 — 3,114,821 Equity investments 5,154,970 1,218,592 — 472,217 (6,836,348 ) 9,431 Other assets, net 46,836 499,714 44,191 133,641 (315,967 ) 408,415 Total assets $ 6,004,042 $ 5,894,024 $ 1,376,156 $ 1,470,014 $ (9,019,835 ) $ 5,724,401 Current liabilities Accounts and notes payable $ 1,834,419 $ 138,467 $ 36,118 $ 87,489 $ (1,839,109 ) $ 257,384 Accrued liabilities 15,686 138,401 34,991 88,110 (28,411 ) 248,777 Total current liabilities 1,850,105 276,868 71,109 175,599 (1,867,520 ) 506,161 Long-term debt 747,411 10,889 308,184 — (308,184 ) 758,300 Deferred income taxes — 565,865 1,571 50,099 (7,783 ) 609,752 Other liabilities — 43,015 — 102,771 — 145,786 Total liabilities 2,597,516 896,637 380,864 328,469 (2,183,487 ) 2,019,999 Total Westlake Chemical Corporation stockholders' equity 3,406,526 4,997,387 995,292 843,669 (6,836,348 ) 3,406,526 Noncontrolling interests — — — 297,876 — 297,876 Total equity 3,406,526 4,997,387 995,292 1,141,545 (6,836,348 ) 3,704,402 Total liabilities and equity $ 6,004,042 $ 5,894,024 $ 1,376,156 $ 1,470,014 $ (9,019,835 ) $ 5,724,401 Condensed Consolidating Financial Information as of December 31, 2015 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non-Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 303,131 $ 6,828 $ 163,430 $ 189,136 $ — $ 662,525 Marketable securities 520,144 — — — — 520,144 Accounts receivable, net 10,943 2,183,276 51,582 113,321 (1,850,590 ) 508,532 Inventories — 326,588 3,879 103,593 — 434,060 Prepaid expenses and other current assets 2,201 12,166 267 2,734 (2,879 ) 14,489 Deferred income taxes 702 32,787 — 1,950 — 35,439 Total current assets 837,121 2,561,645 219,158 410,734 (1,853,469 ) 2,175,189 Property, plant and equipment, net — 1,567,897 1,020,469 415,701 — 3,004,067 Equity investments 4,991,167 1,207,679 — 469,915 (6,659,553 ) 9,208 Other assets, net 11,929 450,428 44,157 129,539 (255,232 ) 380,821 Total assets $ 5,840,217 $ 5,787,649 $ 1,283,784 $ 1,425,889 $ (8,768,254 ) $ 5,569,285 Current liabilities Accounts payable $ 1,817,963 $ 121,820 $ 33,901 $ 87,510 $ (1,825,865 ) $ 235,329 Accrued liabilities 9,117 195,785 21,873 88,142 (27,604 ) 287,313 Total current liabilities 1,827,080 317,605 55,774 175,652 (1,853,469 ) 522,642 Long-term debt 747,259 10,889 248,665 — (248,665 ) 758,148 Deferred income taxes — 532,837 1,392 47,941 (6,567 ) 575,603 Other liabilities — 49,334 — 101,627 — 150,961 Total liabilities 2,574,339 910,665 305,831 325,220 (2,108,701 ) 2,007,354 Total Westlake Chemical Corporation stockholders' equity 3,265,878 4,876,984 977,953 804,616 (6,659,553 ) 3,265,878 Noncontrolling interests — — — 296,053 — 296,053 Total equity 3,265,878 4,876,984 977,953 1,100,669 (6,659,553 ) 3,561,931 Total liabilities and equity $ 5,840,217 $ 5,787,649 $ 1,283,784 $ 1,425,889 $ (8,768,254 ) $ 5,569,285
Condensed Consolidating Financial Information Statement Of Operations	Condensed Consolidating Financial Information for the Three Months Ended March 31, 2016 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 784,060 $ 252,604 $ 262,915 $ (324,392 ) $ 975,187 Cost of sales — 665,462 142,190 230,874 (318,924 ) 719,602 Gross profit — 118,598 110,414 32,041 (5,468 ) 255,585 Selling, general and administrative expenses 607 40,628 5,278 12,264 (5,468 ) 53,309 (Loss) income from operations (607 ) 77,970 105,136 19,777 — 202,276 Interest expense (10,411 ) (3 ) (251 ) (78 ) 4,058 (6,685 ) Other income (expense), net 1,815 6,445 84 (1,641 ) (4,058 ) 2,645 (Loss) income before income taxes (9,203 ) 84,412 104,969 18,058 — 198,236 (Benefit from) provision for income taxes (3,219 ) 66,580 399 5,540 — 69,300 Equity in net income of subsidiaries 129,112 90,687 — 13,883 (233,682 ) — Net income 123,128 108,519 104,570 26,401 (233,682 ) 128,936 Net income attributable to noncontrolling interests — — — 5,808 — 5,808 Net income attributable to Westlake Chemical Corporation $ 123,128 $ 108,519 $ 104,570 $ 20,593 $ (233,682 ) $ 123,128 Comprehensive income attributable to Westlake Chemical Corporation $ 161,757 $ 120,405 $ 104,570 $ 43,398 $ (268,373 ) $ 161,757 Condensed Consolidating Financial Information for the Three Months Ended March 31, 2015 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 903,492 $ 258,391 $ 245,643 $ (303,995 ) $ 1,103,531 Cost of sales — 727,399 162,164 228,269 (298,847 ) 818,985 Gross profit — 176,093 96,227 17,374 (5,148 ) 284,546 Selling, general and administrative expenses 413 43,684 5,046 11,271 (5,148 ) 55,266 (Loss) income from operations (413 ) 132,409 91,181 6,103 — 229,280 Interest expense (10,752 ) (1 ) (1,376 ) (42 ) 2,580 (9,591 ) Other income, net 6,612 2,827 5 2,232 (2,580 ) 9,096 (Loss) income before income taxes (4,553 ) 135,235 89,810 8,293 — 228,785 (Benefit from) provision for income taxes (1,578 ) 77,999 467 1,490 — 78,378 Equity in net income of subsidiaries 149,317 79,891 — 9,452 (238,660 ) — Net income 146,342 137,127 89,343 16,255 (238,660 ) 150,407 Net income attributable to noncontrolling interests — — — 4,065 — 4,065 Net income attributable to Westlake Chemical Corporation $ 146,342 $ 137,127 $ 89,343 $ 12,190 $ (238,660 ) $ 146,342 Comprehensive income (loss) attributable to Westlake Chemical Corporation $ 88,113 $ 137,365 $ 89,343 $ (47,319 ) $ (179,389 ) $ 88,113
Condensed Consolidating Financial Information Statement Of Cash Flows	Condensed Consolidating Financial Information as of March 31, 2016 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 263,150 $ 1,164 $ 170,755 $ 179,907 $ — $ 614,976 Marketable securities 525,008 — — — — 525,008 Accounts receivable, net 11,705 2,205,593 62,109 133,547 (1,863,917 ) 549,037 Inventories — 363,470 2,590 112,596 — 478,656 Prepaid expenses and other current assets 2,373 16,525 157 8,605 (3,603 ) 24,057 Total current assets 802,236 2,586,752 235,611 434,655 (1,867,520 ) 2,191,734 Property, plant and equipment, net — 1,588,966 1,096,354 429,501 — 3,114,821 Equity investments 5,154,970 1,218,592 — 472,217 (6,836,348 ) 9,431 Other assets, net 46,836 499,714 44,191 133,641 (315,967 ) 408,415 Total assets $ 6,004,042 $ 5,894,024 $ 1,376,156 $ 1,470,014 $ (9,019,835 ) $ 5,724,401 Current liabilities Accounts and notes payable $ 1,834,419 $ 138,467 $ 36,118 $ 87,489 $ (1,839,109 ) $ 257,384 Accrued liabilities 15,686 138,401 34,991 88,110 (28,411 ) 248,777 Total current liabilities 1,850,105 276,868 71,109 175,599 (1,867,520 ) 506,161 Long-term debt 747,411 10,889 308,184 — (308,184 ) 758,300 Deferred income taxes — 565,865 1,571 50,099 (7,783 ) 609,752 Other liabilities — 43,015 — 102,771 — 145,786 Total liabilities 2,597,516 896,637 380,864 328,469 (2,183,487 ) 2,019,999 Total Westlake Chemical Corporation stockholders' equity 3,406,526 4,997,387 995,292 843,669 (6,836,348 ) 3,406,526 Noncontrolling interests — — — 297,876 — 297,876 Total equity 3,406,526 4,997,387 995,292 1,141,545 (6,836,348 ) 3,704,402 Total liabilities and equity $ 6,004,042 $ 5,894,024 $ 1,376,156 $ 1,470,014 $ (9,019,835 ) $ 5,724,401 Condensed Consolidating Financial Information as of December 31, 2015 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non-Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 303,131 $ 6,828 $ 163,430 $ 189,136 $ — $ 662,525 Marketable securities 520,144 — — — — 520,144 Accounts receivable, net 10,943 2,183,276 51,582 113,321 (1,850,590 ) 508,532 Inventories — 326,588 3,879 103,593 — 434,060 Prepaid expenses and other current assets 2,201 12,166 267 2,734 (2,879 ) 14,489 Deferred income taxes 702 32,787 — 1,950 — 35,439 Total current assets 837,121 2,561,645 219,158 410,734 (1,853,469 ) 2,175,189 Property, plant and equipment, net — 1,567,897 1,020,469 415,701 — 3,004,067 Equity investments 4,991,167 1,207,679 — 469,915 (6,659,553 ) 9,208 Other assets, net 11,929 450,428 44,157 129,539 (255,232 ) 380,821 Total assets $ 5,840,217 $ 5,787,649 $ 1,283,784 $ 1,425,889 $ (8,768,254 ) $ 5,569,285 Current liabilities Accounts payable $ 1,817,963 $ 121,820 $ 33,901 $ 87,510 $ (1,825,865 ) $ 235,329 Accrued liabilities 9,117 195,785 21,873 88,142 (27,604 ) 287,313 Total current liabilities 1,827,080 317,605 55,774 175,652 (1,853,469 ) 522,642 Long-term debt 747,259 10,889 248,665 — (248,665 ) 758,148 Deferred income taxes — 532,837 1,392 47,941 (6,567 ) 575,603 Other liabilities — 49,334 — 101,627 — 150,961 Total liabilities 2,574,339 910,665 305,831 325,220 (2,108,701 ) 2,007,354 Total Westlake Chemical Corporation stockholders' equity 3,265,878 4,876,984 977,953 804,616 (6,659,553 ) 3,265,878 Noncontrolling interests — — — 296,053 — 296,053 Total equity 3,265,878 4,876,984 977,953 1,100,669 (6,659,553 ) 3,561,931 Total liabilities and equity $ 5,840,217 $ 5,787,649 $ 1,283,784 $ 1,425,889 $ (8,768,254 ) $ 5,569,285 Condensed Consolidating Financial Information for the Three Months Ended March 31, 2016 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 784,060 $ 252,604 $ 262,915 $ (324,392 ) $ 975,187 Cost of sales — 665,462 142,190 230,874 (318,924 ) 719,602 Gross profit — 118,598 110,414 32,041 (5,468 ) 255,585 Selling, general and administrative expenses 607 40,628 5,278 12,264 (5,468 ) 53,309 (Loss) income from operations (607 ) 77,970 105,136 19,777 — 202,276 Interest expense (10,411 ) (3 ) (251 ) (78 ) 4,058 (6,685 ) Other income (expense), net 1,815 6,445 84 (1,641 ) (4,058 ) 2,645 (Loss) income before income taxes (9,203 ) 84,412 104,969 18,058 — 198,236 (Benefit from) provision for income taxes (3,219 ) 66,580 399 5,540 — 69,300 Equity in net income of subsidiaries 129,112 90,687 — 13,883 (233,682 ) — Net income 123,128 108,519 104,570 26,401 (233,682 ) 128,936 Net income attributable to noncontrolling interests — — — 5,808 — 5,808 Net income attributable to Westlake Chemical Corporation $ 123,128 $ 108,519 $ 104,570 $ 20,593 $ (233,682 ) $ 123,128 Comprehensive income attributable to Westlake Chemical Corporation $ 161,757 $ 120,405 $ 104,570 $ 43,398 $ (268,373 ) $ 161,757 Condensed Consolidating Financial Information for the Three Months Ended March 31, 2015 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 903,492 $ 258,391 $ 245,643 $ (303,995 ) $ 1,103,531 Cost of sales — 727,399 162,164 228,269 (298,847 ) 818,985 Gross profit — 176,093 96,227 17,374 (5,148 ) 284,546 Selling, general and administrative expenses 413 43,684 5,046 11,271 (5,148 ) 55,266 (Loss) income from operations (413 ) 132,409 91,181 6,103 — 229,280 Interest expense (10,752 ) (1 ) (1,376 ) (42 ) 2,580 (9,591 ) Other income, net 6,612 2,827 5 2,232 (2,580 ) 9,096 (Loss) income before income taxes (4,553 ) 135,235 89,810 8,293 — 228,785 (Benefit from) provision for income taxes (1,578 ) 77,999 467 1,490 — 78,378 Equity in net income of subsidiaries 149,317 79,891 — 9,452 (238,660 ) — Net income 146,342 137,127 89,343 16,255 (238,660 ) 150,407 Net income attributable to noncontrolling interests — — — 4,065 — 4,065 Net income attributable to Westlake Chemical Corporation $ 146,342 $ 137,127 $ 89,343 $ 12,190 $ (238,660 ) $ 146,342 Comprehensive income (loss) attributable to Westlake Chemical Corporation $ 88,113 $ 137,365 $ 89,343 $ (47,319 ) $ (179,389 ) $ 88,113 Condensed Consolidating Financial Information for the Three Months Ended March 31, 2016 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Cash Flows Cash flows from operating activities Net income $ 123,128 $ 108,519 $ 104,570 $ 26,401 $ (233,682 ) $ 128,936 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization 220 35,383 20,396 9,935 — 65,934 Deferred income taxes (2,724 ) 59,139 179 2,043 — 58,637 Net changes in working capital and other (120,565 ) (188,331 ) (11,115 ) (38,243 ) 233,682 (124,572 ) Net cash provided by operating activities 59 14,710 114,030 136 — 128,935 Cash flows from investing activities Additions to property, plant and equipment — (50,568 ) (79,091 ) (6,669 ) — (136,328 ) Proceeds from disposition of assets — 6 98 — — 104 Proceeds from sales and maturities of securities 26,859 — — — — 26,859 Purchase of securities (29,045 ) (7,592 ) — — — (36,637 ) Settlements of derivative instruments — (1,219 ) — — — (1,219 ) Net cash used for investing activities (2,186 ) (59,373 ) (78,993 ) (6,669 ) — (147,221 ) Cash flows from financing activities Intercompany financing (13,763 ) (41,000 ) 59,519 (4,756 ) — — Dividends paid (23,700 ) — — — — (23,700 ) Distributions paid — 79,999 (87,231 ) 3,247 — (3,985 ) Proceeds from exercise of stock options 22 — — — — 22 Proceeds from issuance of notes payable — — — 2,050 — 2,050 Repayment of notes payable — — — (7,095 ) — (7,095 ) Repurchase of common stock for treasury (679 ) — — — — (679 ) Windfall tax benefits from share-based payment arrangements 266 — — — — 266 Net cash (used for) provided by financing activities (37,854 ) 38,999 (27,712 ) (6,554 ) — (33,121 ) Effect of exchange rate changes on cash and cash equivalents — — — 3,858 — 3,858 Net (decrease) increase in cash and cash equivalents (39,981 ) (5,664 ) 7,325 (9,229 ) — (47,549 ) Cash and cash equivalents at beginning of period 303,131 6,828 163,430 189,136 — 662,525 Cash and cash equivalents at end of period $ 263,150 $ 1,164 $ 170,755 $ 179,907 $ — $ 614,976 Condensed Consolidating Financial Information for the Three Months Ended March 31, 2015 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries OpCo (Less Than 100% Owned Guarantor Subsidiary) Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Cash Flows Cash flows from operating activities Net income $ 146,342 $ 137,127 $ 89,343 $ 16,255 $ (238,660 ) $ 150,407 Adjustments to reconcile net income to net cash (used for) provided by operating activities Depreciation and amortization 501 29,592 19,803 9,246 — 59,142 Deferred income taxes (124 ) 6,431 54 (1,030 ) — 5,331 Net changes in working capital and other (151,572 ) (114,779 ) 6,973 (3,606 ) 238,660 (24,324 ) Net cash (used for) provided by operating activities (4,853 ) 58,371 116,173 20,865 — 190,556 Cash flows from investing activities Additions to property, plant and equipment — (47,385 ) (39,540 ) (8,897 ) — (95,822 ) Settlements of derivative instruments — (833 ) — — — (833 ) Net cash used for investing activities — (48,218 ) (39,540 ) (8,897 ) — (96,655 ) Cash flows from financing activities Intercompany financing 72,634 (99,765 ) 30,191 (3,060 ) — — Dividends paid (21,964 ) — — — — (21,964 ) Distributions paid — 89,161 (95,364 ) 2,645 — (3,558 ) Proceeds from exercise of stock options 157 — — — — 157 Repurchase of common stock for treasury (2,000 ) — — — — (2,000 ) Windfall tax benefits from share-based payment arrangements 1,701 — — — — 1,701 Net cash provided by (used for) financing activities 50,528 (10,604 ) (65,173 ) (415 ) — (25,664 ) Effect of exchange rate changes on cash and cash equivalents — — — (3,189 ) — (3,189 ) Net increase (decrease) in cash and cash equivalents 45,675 (451 ) 11,460 8,364 — 65,048 Cash and cash equivalents at beginning of period 655,947 3,057 131,545 90,052 — 880,601 Cash and cash equivalents at end of period $ 701,622 $ 2,606 $ 143,005 $ 98,416 $ — $ 945,649

Basis of Financial Statements B

Basis of Financial Statements Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred costs and other assets	$ 194,907	$ 167,417
Long-term debt, net	$ 758,300	758,148
Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred costs and other assets		173,384
Long-term debt, net		$ 764,115

Financial Instruments Cash Equi

Financial Instruments Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Held-to-maturity Securities [Member]
Cash Equivalents [Line Items]
Cash equivalents	$ 292,903	$ 221,918

Financial Instruments (Marketab

Financial Instruments (Marketable Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Current	$ 525,008	$ 520,144
Noncurrent	75,114	48,081
Total available-for-sale securities	$ 600,122	$ 568,225

Financial Instruments (Availabl

Financial Instruments (Available-for-sale Securities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 583,542	$ 576,021
Gross Unrealized Gains	16,883	525
Gross Unrealized Losses	(303)	(8,321)
Fair Value	600,122	568,225
Net unrealized gains (losses) on available-for-sale securities	10,623	(4,995)
Income tax expense (benefits) on gains (losses) from available-for-sale securities	5,957	(2,801)
Proceeds from sales and maturities of securities	26,859
Gross realized gains	61
Gross realized losses	(9)
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	60,283	54,371
Gross Unrealized Gains	14,927	466
Gross Unrealized Losses	(96)	(6,756)
Fair Value	75,114	48,081
Corporate bond securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	341,856	336,665
Gross Unrealized Gains	1,411	55
Gross Unrealized Losses	(185)	(1,076)
Fair Value	343,082	335,644
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	125,114	135,226
Gross Unrealized Gains	425	2
Gross Unrealized Losses	(9)	(374)
Fair Value	125,530	134,854
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	56,289	49,759
Gross Unrealized Gains	120	2
Gross Unrealized Losses	(13)	(115)
Fair Value	$ 56,396	$ 49,646

Financial Instruments (Maturity

Financial Instruments (Maturity Periods for Investments) (Details)	3 Months Ended
	Mar. 31, 2016
Corporate bond securities [Member] | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	1 month
Corporate bond securities [Member] | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	5 years
US Government Agencies Debt Securities [Member] | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	1 month
US Government Agencies Debt Securities [Member] | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	4 years
Mortgage backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	5 years
Asset-backed securities [Member] | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	1 month
Asset-backed securities [Member] | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	5 years

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts Receivable, Net [Abstract]
Trade customers	$ 465,697	$ 438,538
Allowance for doubtful accounts	(14,321)	(14,095)
Receivables from trade customers and affiliates, net	451,376	424,443
Federal and state taxes	81,255	60,748
Other	16,406	23,341
Accounts receivable, net	$ 549,037	$ 508,532

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Finished products	$ 298,236	$ 253,338
Feedstock, additives and chemicals	103,837	106,435
Materials and supplies	76,583	74,287
Inventories	$ 478,656	$ 434,060

Property, Plant and Equipment (

Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	$ 3,114,821		$ 3,004,067
Depreciation expense on property, plant and equipment	$ 56,041	$ 49,658

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Olefins [Member]
Other Assets [Line Items]
Goodwill	$ 29,990		$ 29,990
Vinyls [Member]
Other Assets [Line Items]
Goodwill	32,026		$ 32,026
Other assets [Member]
Other Assets [Line Items]
Amortization	$ 9,770	$ 9,361

Accounts and Notes Payable (Det

Accounts and Notes Payable (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts and Notes Payable [Abstract]
Accounts payable	$ 256,351	$ 229,219
Notes payable to banks	1,033	6,110
Accounts and notes payable	$ 257,384	$ 235,329

Long-Term Debt (Schedule of Lon

Long-Term Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Deferred costs and other assets	$ 194,907	$ 167,417
Long-term debt, principal amount	764,889	764,889
Unamortized discount and debt issuance costs	(6,589)	(6,741)
Long-term debt, net	$ 758,300	758,148
3.60% Senior Notes Due 2022
Debt Instrument [Line Items]
Maturity date	2,022
Stated interest rate	3.60%
6 1/2% Senior Notes Due 2029
Debt Instrument [Line Items]
Maturity date	2,029
Stated interest rate	6.50%
6 3/4% Senior Notes Due 2032
Debt Instrument [Line Items]
Maturity date	2,032
Stated interest rate	6.75%
2035 GO Zone 6 1/2% Notes
Debt Instrument [Line Items]
Maturity date	2,035
Stated interest rate	6.50%
2035 IKE Zone 6 1/2% Notes
Debt Instrument [Line Items]
Maturity date	2,035
Stated interest rate	6.50%
Loan related to tax-exempt waste disposal revenue bonds due 2027
Debt Instrument [Line Items]
Maturity date	2,027
Loan related to tax-exempt waste disposal revenue bonds due 2027 | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 10,889	10,889
Unamortized discount and debt issuance costs	0	0
Long-term debt, net	10,889	10,889
2035 IKE Zone 6 1/2% Notes | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, principal amount	65,000	65,000
Unamortized discount and debt issuance costs	(626)	(634)
Long-term debt, net	64,374	64,366
2035 GO Zone 6 1/2% Notes | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, principal amount	89,000	89,000
Unamortized discount and debt issuance costs	(873)	(884)
Long-term debt, net	88,127	88,116
6 3/4% Senior Notes Due 2032 | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, principal amount	250,000	250,000
Unamortized discount and debt issuance costs	(1,972)	(2,002)
Long-term debt, net	248,028	247,998
6 1/2% Senior Notes Due 2029 | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, principal amount	100,000	100,000
Unamortized discount and debt issuance costs	(971)	(989)
Long-term debt, net	99,029	99,011
3.60% Senior Notes Due 2022 | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, principal amount	250,000	250,000
Unamortized discount and debt issuance costs	(2,147)	(2,232)
Long-term debt, net	$ 247,853	247,768
Previously Reported [Member]
Debt Instrument [Line Items]
Deferred costs and other assets		173,384
Long-term debt, net		$ 764,115

Long-Term Debt (Revolving Credi

Long-Term Debt (Revolving Credit Facility) (Details) - Line of Credit	3 Months Ended
	Mar. 31, 2016USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 400,000,000
Revolving credit facility, amount outstanding	$ 0
Percentage of commitment on borrowing availability	0.25%
Letters of credit outstanding	$ 30,445,000
Remaining borrowing capacity	$ 354,821,000
LIBOR [Member]
Line of Credit Facility [Line Items]
Maximum basis spread, provided company is rated investment grade	1.50%
Minimum
Line of Credit Facility [Line Items]
Increase in credit facility borrowings	$ 25,000,000
Minimum | LIBOR [Member]
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	1.25%
Minimum | Base Rate [Member]
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	0.00%
Maximum
Line of Credit Facility [Line Items]
Increase in credit facility borrowings	$ 200,000,000
Maximum | LIBOR [Member]
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	1.75%
Maximum | Base Rate [Member]
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	0.50%

Stockholders' Equity (Changes i

Stockholders' Equity (Changes in Stockholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance	$ 3,561,931	$ 3,201,888
Net income	128,936	150,407
Pension and other post- retirement benefits liability	206	427
Foreign currency translation adjustments	22,805	(59,698)
Net unrealized holding gains on investments	15,618	1,042
Common stock repurchased		(2,000)
Shares issued—stock- based compensation	22	157
Stock-based compensation, net of tax on stock options exercised	2,569	4,041
Dividends paid	(23,700)	(21,964)
Distributions to noncontrolling interests	(3,985)	(3,558)
Amount, ending balance	3,704,402	3,270,742
Common Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance	1,347	1,347
Shares issued—stock- based compensation	0	0
Amount, ending balance	1,347	1,347
Treasury Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance	(258,312)	(96,372)
Common stock repurchased		(2,000)
Shares issued—stock- based compensation	1,853	97
Amount, ending balance	(256,459)	(98,275)
Additional Paid-in Capital [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance	542,148	530,441
Shares issued—stock- based compensation	(1,831)	60
Stock-based compensation, net of tax on stock options exercised	2,569	4,041
Amount, ending balance	542,886	534,542
Retained Earnings [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance	3,109,987	2,555,528
Net income	123,128	146,342
Dividends paid	(23,700)	(21,964)
Amount, ending balance	3,209,415	2,679,906
AOCI Attributable to Parent [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance	(129,292)	(79,433)
Pension and other post- retirement benefits liability	206	427
Foreign currency translation adjustments	22,805	(59,698)
Net unrealized holding gains on investments	15,618	1,042
Amount, ending balance	(90,663)	(137,662)
Noncontrolling Interest [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance	296,053	290,377
Net income	5,808	4,065
Distributions to noncontrolling interests	(3,985)	(3,558)
Amount, ending balance	$ 297,876	$ 290,884

Stockholders' Equity (Changes54

Stockholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss (income), balance	$ 3,704,402	$ 3,270,742	$ 3,561,931	$ 3,201,888
Amounts reclassified from accumulated other comprehensive loss (income)	173	427
Other comprehensive income (loss)	38,629	(58,229)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss (income), balance	(8,401)	(23,015)	(8,607)	(23,442)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss (income)	206	427
Other comprehensive income (loss)	206	427
Accumulated Foreign Currency Adjustment to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss (income), balance	(92,885)	(115,922)	(115,690)	(56,224)
Other comprehensive income (loss) before reclassifications	22,805	(59,698)
Amounts reclassified from accumulated other comprehensive loss (income)	0	0
Other comprehensive income (loss)	22,805	(59,698)
Accumulated Net Unrealized Gain (Loss) On Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss (income), balance	10,623	1,275	(4,995)	233
Other comprehensive income (loss) before reclassifications	15,651	1,042
Amounts reclassified from accumulated other comprehensive loss (income)	(33)	0
Other comprehensive income (loss)	15,618	1,042
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss (income), balance	(90,663)	(137,662)	$ (129,292)	$ (79,433)
Other comprehensive income (loss) before reclassifications	38,456	(58,656)
Amounts reclassified from accumulated other comprehensive loss (income)	173	427
Other comprehensive income (loss)	$ 38,629	$ (58,229)

Stockholders' Equity (Reclassif

Stockholders' Equity (Reclassifications in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income, net	$ 2,645	$ 9,096
Provision for income taxes, investments	(69,300)	(78,378)
Total reclassifications for the period	(173)	(427)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of pension and other post-retirement items, net loss	(334)	(652)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision for income taxes, defined benefit plan	128	225
Total reclassifications for the period	(206)	(427)
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	52	0
Provision for income taxes, investments	(19)	0
Income (loss), including portion attributable to noncontrolling interest	$ 33	$ 0

Pension and Post-Retirement B56

Pension and Post-Retirement Benefit Costs (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
United States Pension Plan of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 28
Interest cost	567	544
Expected return on plan assets	(802)	(819)
Amortization of net loss	303	290
Net periodic benefit cost	68	43
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	323	422
Interest cost	568	535
Expected return on plan assets	0	0
Amortization of net loss	0	266
Net periodic benefit cost	891	1,223
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	6
Interest cost	145	149
Amortization of net loss	31	96
Net periodic benefit cost	$ 181	$ 251

Pension and Post-Retirement B57

Pension and Post-Retirement Benefit Costs (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Wage Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 0	$ 112
Estimated future employer contributions for next fiscal year	900
Salaried Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	0	$ 0
Estimated future employer contributions for next fiscal year	$ 900

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	$ 2,303	$ 2,340

Derivative Instruments (Fair Va

Derivative Instruments (Fair Values of Derivative Instruments in Consolidated Balance Sheets) (Details) - Not Designated as Hedging Instrument [Member] - Commodity Forward Contracts [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	$ 5,955	$ 5,553
Fair value of derivative liabilities	16,867	21,762
Accrued liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	7,730	9,325
Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	9,137	12,437
Accounts receivable, net
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	4,239	3,465
Deferred charges and other assets, net [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	$ 1,716	$ 2,088

Derivative Instruments (Impact

Derivative Instruments (Impact of Derivative Instruments on Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] | Cost of Sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	$ 4,057	$ 4,241

Derivative Instruments Derivati

Derivative Instruments Derivative Commodity Instruments (Offsetting Asset) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Offsetting Assets [Line Items]
Derivative assets subject to enforceable master netting arrangements	$ 340	$ 0
Derivative assets not subject to enforceable master netting arrangements	513	462
Total derivative assets	853	462
Commodity Forward Contracts [Member]
Offsetting Assets [Line Items]
Derivative assets subject to enforceable master netting arrangements	340	0
Gross amounts of recognized assets	5,442	5,091
Gross amount offset in the consolidated balance sheet	(5,102)	(5,091)
Subject to Master Netting [Member] | Commodity Forward Contracts [Member] | Counterparty A [Member]
Offsetting Assets [Line Items]
Derivative assets subject to enforceable master netting arrangements	340	0
Gross amounts not offset in the consolidated balance sheet	0	0
Derivative ssset, amount offset against collateral	$ 340	$ 0

Derivative Instruments Deriva62

Derivative Instruments Derivative Commodity Instruments (Offsetting Liability) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Offsetting Liabilities [Line Items]
Derivative liabilities subject to enforceable master netting arrangements	$ 3,278	$ 5,803
Derivative liabilities not subject to enforceable master netting arrangements	8,487	10,868
Total derivative liabilities	11,765	16,671
Gross amounts not offset in the consolidated balance sheet	0	0
Derivative liability, net amount offset against collateral	3,278	5,803
Commodity Forward Contracts [Member]
Offsetting Liabilities [Line Items]
Derivative liabilities subject to enforceable master netting arrangements	3,278	5,803
Gross amounts of recognized liabilities	8,380	10,894
Gross amounts offset in the consolidated balance sheet	(5,102)	(5,091)
Counterparty A [Member] | Subject to Master Netting [Member] | Commodity Forward Contracts [Member]
Offsetting Liabilities [Line Items]
Derivative liabilities subject to enforceable master netting arrangements	3,149	5,564
Gross amounts not offset in the consolidated balance sheet	0	0
Derivative liability, net amount offset against collateral	3,149	5,564
Counterparty B [Member] | Subject to Master Netting [Member] | Commodity Forward Contracts [Member]
Offsetting Liabilities [Line Items]
Derivative liabilities subject to enforceable master netting arrangements	129	239
Gross amounts not offset in the consolidated balance sheet	0	0
Derivative liability, net amount offset against collateral	$ 129	$ 239

Fair Value Measurements (Summar

Fair Value Measurements (Summary of Assets and Liabilities Accounted at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 600,122	$ 568,225
Commodity Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	5,442	5,091
Risk management liabilities - Commodity forward contracts	(8,380)	(10,894)
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	600,122	568,225
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	75,114	48,081
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	525,008	520,144
Recurring | Commodity Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	5,955	5,553
Risk management liabilities - Commodity forward contracts	(16,867)	(21,762)
Recurring | Commodity Forward Contracts [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	5,896	5,553
Risk management liabilities - Commodity forward contracts	(11,983)	(11,648)
Recurring | Commodity Forward Contracts [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	59	0
Risk management liabilities - Commodity forward contracts	$ (4,884)	$ (10,114)

Fair Value Measurements (Summ64

Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
3.60% Senior Notes Due 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity date	2,022
Stated interest rate	3.60%
3.60% Senior Notes Due 2022 | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 247,853	$ 247,768
3.60% Senior Notes Due 2022 | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 245,500	244,828
6 1/2% Senior Notes Due 2029
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity date	2,029
Stated interest rate	6.50%
6 1/2% Senior Notes Due 2029 | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 99,029	99,011
6 1/2% Senior Notes Due 2029 | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 115,436	117,153
6 3/4% Senior Notes Due 2032
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity date	2,032
Stated interest rate	6.75%
6 3/4% Senior Notes Due 2032 | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 248,028	247,998
6 3/4% Senior Notes Due 2032 | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 267,593	268,490
2035 GO Zone 6 1/2% Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity date	2,035
Stated interest rate	6.50%
2035 GO Zone 6 1/2% Notes | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 88,127	88,116
2035 GO Zone 6 1/2% Notes | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 106,167	106,491
2035 IKE Zone 6 1/2% Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity date	2,035
Stated interest rate	6.50%
2035 IKE Zone 6 1/2% Notes | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 64,374	64,366
2035 IKE Zone 6 1/2% Notes | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 77,538	76,741
Loan related to tax-exempt waste disposal revenue bonds due 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity date	2,027
Loan related to tax-exempt waste disposal revenue bonds due 2027 | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 10,889	10,889
Loan related to tax-exempt waste disposal revenue bonds due 2027 | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 10,889	$ 10,889

Income Taxes (Detail)

Income Taxes (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	35.00%	34.30%
U.S. federal statutory income tax rate	35.00%	35.00%
Anticipated reductions to unrecognized tax benefits within next twelve months	$ 0
Income Tax Examination, Penalties and Interest Accrued	0
Undistributed Earnings of Foreign Subsidiaries	$ 115,000,000

Earnings per Share (Additional

Earnings per Share (Additional Information) (Detail) - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Number of options excluded from computation of diluted earnings per share	555,948	241,312

Earnings per Share (Schedule of

Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 123,128	$ 146,342
Less: Net income attributable to participating securities	(549)	(200)
Net income attributable to common shareholders	$ 122,579	$ 146,142

Earnings per Share (Reconciliat

Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Weighted average common shares—basic	130,189,964	132,714,566
Plus incremental shares from: Assumed exercise of options	410,550	490,740
Weighted average common shares-diluted	130,600,514	133,205,306
Earnings per share: Basic (usd per share)	$ 0.94	$ 1.10
Earnings per share: Diluted (usd per share)	$ 0.94	$ 1.10

Supplemental Information (Detai

Supplemental Information (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accrued Liabilities [Abstract]
Accrued liabilities	$ 248,777	$ 287,313
Accrued capital expenditures	32,037	21,597
Accrued incentive compensation	25,680	41,168
Other Liabilities [Abstract]
Other liabilities	145,786	150,961
Non-current pension obligation	$ 107,413	$ 106,250

Insurance Recovery (Details)

Insurance Recovery (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Insurance Recovery [Abstract]
Insurance recovery	$ 2,670	$ 7,809

Commitments and Contingencies (

Commitments and Contingencies (Additional Information) (Detail) $ in Thousands	3 Months Ended	12 Months Ended	104 Months Ended
	Mar. 31, 2016USD ($)claim	Dec. 31, 2015USD ($)	Mar. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Line Items]
Number of claims settled | claim	2
Settled Litigation [Member]
Commitments and Contingencies Disclosure [Line Items]
Amount of settlement for compliance violations	$ 192
Goodrich And PolyOne [Member]
Commitments and Contingencies Disclosure [Line Items]
Costs incurred for environmental remediation services		$ 2,210
Goodrich And PolyOne [Member] | Settled Litigation [Member]
Commitments and Contingencies Disclosure [Line Items]
Percentage of costs related to environmental issues to be paid by PolyOne			100.00%
Minimum number of years between arbitrations			5 years
Goodrich And PolyOne [Member] | Pending Litigation [Member]
Commitments and Contingencies Disclosure [Line Items]
Reimbursement of remediation costs sought by PolyOne			$ 1,400

Segment Information (Additional

Segment Information (Additional Information) (Detail)	3 Months Ended
	Mar. 31, 2016Segment
Segment Reporting [Abstract]
Number of segments	2

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Net external sales	$ 975,187	$ 1,103,531
Income (loss) from operations	202,276	229,280
Depreciation and amortization	65,714	58,641
Other income (expense), net	2,645	9,096
Provision for (benefit from) income taxes	69,300	78,378
Capital expenditures	136,328	95,822
Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales	431,020	583,077
Income (loss) from operations	149,235	191,103
Depreciation and amortization	28,697	26,939
Other income (expense), net	1,513	2,552
Provision for (benefit from) income taxes	52,533	66,457
Capital expenditures	95,152	55,300
Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales	544,167	520,454
Income (loss) from operations	62,116	47,086
Depreciation and amortization	36,287	31,584
Other income (expense), net	(1,519)	5,503
Provision for (benefit from) income taxes	17,270	12,805
Capital expenditures	40,256	36,855
Corporate and Other
Segment Reporting Information [Line Items]
Income (loss) from operations	(9,075)	(8,909)
Depreciation and amortization	730	118
Other income (expense), net	2,651	1,041
Provision for (benefit from) income taxes	(503)	(884)
Capital expenditures	920	3,667
Polyethylene | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales	346,032	409,432
Ethylene, Styrene And Other | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales	84,988	173,645
PVC, Caustic Soda And Other | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales	430,902	416,988
Building Products | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales	113,265	103,466
Intersegment sales
Segment Reporting Information [Line Items]
Net external sales	28,313	23,832
Intersegment sales | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales	27,949	23,462
Intersegment sales | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales	$ 364	$ 370

Segment Information (Reconcilia

Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting [Abstract]
Income from operations	$ 202,276	$ 229,280
Interest expense	(6,685)	(9,591)
Other income, net	2,645	9,096
Income before income taxes	$ 198,236	$ 228,785

Segment Information (Total Asse

Segment Information (Total Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 5,724,401	$ 5,569,285
Olefins [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,971,395	1,869,888
Vinyls [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,704,560	2,638,833
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,048,446	$ 1,060,564

Guarantor Disclosures (Addition

Guarantor Disclosures (Additional Information) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)
Condensed Financial Statements, Captions [Line Items]
Less than percentage owned in subsidiary	100.00%
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
3.60% Senior Notes Due 2022
Condensed Financial Statements, Captions [Line Items]
Stated interest rate	3.60%
Maturity date	2,022
Minimum debt amount guaranteed by subsidiaries	$ 5,000

Guarantor Disclosures (Condense

Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 614,976	$ 662,525	$ 945,649	$ 880,601
Marketable securities	525,008	520,144
Accounts receivable, net	549,037	508,532
Inventories	478,656	434,060
Prepaid expenses and other current assets	24,057	14,489
Deferred income taxes	0	35,439
Total current assets	2,191,734	2,175,189
Property, plant and equipment, net	3,114,821	3,004,067
Equity investments	9,431	9,208
Other assets, net	408,415	380,821
Total assets	5,724,401	5,569,285
Accounts payable		235,329
Accounts and notes payable	257,384	235,329
Accrued liabilities	248,777	287,313
Total current liabilities	506,161	522,642
Long-term debt, net	758,300	758,148
Deferred income taxes	609,752	575,603
Other liabilities	145,786	150,961
Total liabilities	2,019,999	2,007,354
Total Westlake Chemical Corporation stockholders' equity	3,406,526	3,265,878
Noncontrolling interests	297,876	296,053
Total equity	3,704,402	3,561,931	3,270,742	3,201,888
Total liabilities and equity	5,724,401	5,569,285
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	263,150	303,131	701,622	655,947
Marketable securities	525,008	520,144
Accounts receivable, net	11,705	10,943
Inventories	0	0
Prepaid expenses and other current assets	2,373	2,201
Deferred income taxes		702
Total current assets	802,236	837,121
Property, plant and equipment, net	0	0
Equity investments	5,154,970	4,991,167
Other assets, net	46,836	11,929
Total assets	6,004,042	5,840,217
Accounts payable		1,817,963
Accounts and notes payable	1,834,419
Accrued liabilities	15,686	9,117
Total current liabilities	1,850,105	1,827,080
Long-term debt, net	747,411	747,259
Deferred income taxes	0	0
Other liabilities	0	0
Total liabilities	2,597,516	2,574,339
Total Westlake Chemical Corporation stockholders' equity	3,406,526	3,265,878
Noncontrolling interests	0	0
Total equity	3,406,526	3,265,878
Total liabilities and equity	6,004,042	5,840,217
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	1,164	6,828	2,606	3,057
Marketable securities	0	0
Accounts receivable, net	2,205,593	2,183,276
Inventories	363,470	326,588
Prepaid expenses and other current assets	16,525	12,166
Deferred income taxes		32,787
Total current assets	2,586,752	2,561,645
Property, plant and equipment, net	1,588,966	1,567,897
Equity investments	1,218,592	1,207,679
Other assets, net	499,714	450,428
Total assets	5,894,024	5,787,649
Accounts payable		121,820
Accounts and notes payable	138,467
Accrued liabilities	138,401	195,785
Total current liabilities	276,868	317,605
Long-term debt, net	10,889	10,889
Deferred income taxes	565,865	532,837
Other liabilities	43,015	49,334
Total liabilities	896,637	910,665
Total Westlake Chemical Corporation stockholders' equity	4,997,387	4,876,984
Noncontrolling interests	0	0
Total equity	4,997,387	4,876,984
Total liabilities and equity	5,894,024	5,787,649
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	170,755	163,430	143,005	131,545
Marketable securities	0	0
Accounts receivable, net	62,109	51,582
Inventories	2,590	3,879
Prepaid expenses and other current assets	157	267
Deferred income taxes		0
Total current assets	235,611	219,158
Property, plant and equipment, net	1,096,354	1,020,469
Equity investments	0	0
Other assets, net	44,191	44,157
Total assets	1,376,156	1,283,784
Accounts payable		33,901
Accounts and notes payable	36,118
Accrued liabilities	34,991	21,873
Total current liabilities	71,109	55,774
Long-term debt, net	308,184	248,665
Deferred income taxes	1,571	1,392
Other liabilities	0	0
Total liabilities	380,864	305,831
Total Westlake Chemical Corporation stockholders' equity	995,292	977,953
Noncontrolling interests	0	0
Total equity	995,292	977,953
Total liabilities and equity	1,376,156	1,283,784
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	179,907	189,136	98,416	90,052
Marketable securities	0	0
Accounts receivable, net	133,547	113,321
Inventories	112,596	103,593
Prepaid expenses and other current assets	8,605	2,734
Deferred income taxes		1,950
Total current assets	434,655	410,734
Property, plant and equipment, net	429,501	415,701
Equity investments	472,217	469,915
Other assets, net	133,641	129,539
Total assets	1,470,014	1,425,889
Accounts payable		87,510
Accounts and notes payable	87,489
Accrued liabilities	88,110	88,142
Total current liabilities	175,599	175,652
Long-term debt, net	0	0
Deferred income taxes	50,099	47,941
Other liabilities	102,771	101,627
Total liabilities	328,469	325,220
Total Westlake Chemical Corporation stockholders' equity	843,669	804,616
Noncontrolling interests	297,876	296,053
Total equity	1,141,545	1,100,669
Total liabilities and equity	1,470,014	1,425,889
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	$ 0	$ 0
Marketable securities	0	0
Accounts receivable, net	(1,863,917)	(1,850,590)
Inventories	0	0
Prepaid expenses and other current assets	(3,603)	(2,879)
Deferred income taxes		0
Total current assets	(1,867,520)	(1,853,469)
Property, plant and equipment, net	0	0
Equity investments	(6,836,348)	(6,659,553)
Other assets, net	(315,967)	(255,232)
Total assets	(9,019,835)	(8,768,254)
Accounts payable		(1,825,865)
Accounts and notes payable	(1,839,109)
Accrued liabilities	(28,411)	(27,604)
Total current liabilities	(1,867,520)	(1,853,469)
Long-term debt, net	(308,184)	(248,665)
Deferred income taxes	(7,783)	(6,567)
Other liabilities	0	0
Total liabilities	(2,183,487)	(2,108,701)
Total Westlake Chemical Corporation stockholders' equity	(6,836,348)	(6,659,553)
Noncontrolling interests	0	0
Total equity	(6,836,348)	(6,659,553)
Total liabilities and equity	$ (9,019,835)	$ (8,768,254)

Guarantor Disclosures (Conden78

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 975,187	$ 1,103,531
Cost of sales	719,602	818,985
Gross profit	255,585	284,546
Selling, general and administrative expenses	53,309	55,266
Income from operations	202,276	229,280
Interest expense	(6,685)	(9,591)
Other income, net	2,645	9,096
Income before income taxes	198,236	228,785
Provision for (benefit from) income taxes	69,300	78,378
Equity in net income of subsidiaries	0	0
Net income	128,936	150,407
Net income attributable to noncontrolling interests	5,808	4,065
Net income attributable to Westlake Chemical Corporation	123,128	146,342
Comprehensive income (loss) attributable to Westlake Chemical Corporation	161,757	88,113
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general and administrative expenses	607	413
Income from operations	(607)	(413)
Interest expense	(10,411)	(10,752)
Other income, net	1,815	6,612
Income before income taxes	(9,203)	(4,553)
Provision for (benefit from) income taxes	(3,219)	(1,578)
Equity in net income of subsidiaries	129,112	149,317
Net income	123,128	146,342
Net income attributable to noncontrolling interests	0	0
Net income attributable to Westlake Chemical Corporation	123,128	146,342
Comprehensive income (loss) attributable to Westlake Chemical Corporation	161,757	88,113
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	784,060	903,492
Cost of sales	665,462	727,399
Gross profit	118,598	176,093
Selling, general and administrative expenses	40,628	43,684
Income from operations	77,970	132,409
Interest expense	(3)	(1)
Other income, net	6,445	2,827
Income before income taxes	84,412	135,235
Provision for (benefit from) income taxes	66,580	77,999
Equity in net income of subsidiaries	90,687	79,891
Net income	108,519	137,127
Net income attributable to noncontrolling interests	0	0
Net income attributable to Westlake Chemical Corporation	108,519	137,127
Comprehensive income (loss) attributable to Westlake Chemical Corporation	120,405	137,365
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Net sales	252,604	258,391
Cost of sales	142,190	162,164
Gross profit	110,414	96,227
Selling, general and administrative expenses	5,278	5,046
Income from operations	105,136	91,181
Interest expense	(251)	(1,376)
Other income, net	84	5
Income before income taxes	104,969	89,810
Provision for (benefit from) income taxes	399	467
Equity in net income of subsidiaries	0	0
Net income	104,570	89,343
Net income attributable to noncontrolling interests	0	0
Net income attributable to Westlake Chemical Corporation	104,570	89,343
Comprehensive income (loss) attributable to Westlake Chemical Corporation	104,570	89,343
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	262,915	245,643
Cost of sales	230,874	228,269
Gross profit	32,041	17,374
Selling, general and administrative expenses	12,264	11,271
Income from operations	19,777	6,103
Interest expense	(78)	(42)
Other income, net	(1,641)	2,232
Income before income taxes	18,058	8,293
Provision for (benefit from) income taxes	5,540	1,490
Equity in net income of subsidiaries	13,883	9,452
Net income	26,401	16,255
Net income attributable to noncontrolling interests	5,808	4,065
Net income attributable to Westlake Chemical Corporation	20,593	12,190
Comprehensive income (loss) attributable to Westlake Chemical Corporation	43,398	(47,319)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(324,392)	(303,995)
Cost of sales	(318,924)	(298,847)
Gross profit	(5,468)	(5,148)
Selling, general and administrative expenses	(5,468)	(5,148)
Income from operations	0	0
Interest expense	4,058	2,580
Other income, net	(4,058)	(2,580)
Income before income taxes	0	0
Provision for (benefit from) income taxes	0	0
Equity in net income of subsidiaries	(233,682)	(238,660)
Net income	(233,682)	(238,660)
Net income attributable to noncontrolling interests	0	0
Net income attributable to Westlake Chemical Corporation	(233,682)	(238,660)
Comprehensive income (loss) attributable to Westlake Chemical Corporation	$ (268,373)	$ (179,389)

Guarantor Disclosures (Conden79

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net income	$ 128,936	$ 150,407
Depreciation, Depletion and Amortization	65,934	59,142
Deferred income taxes	58,637	5,331
Net changes in working capital and other	(124,572)	(24,324)
Net cash provided by operating activities	128,935	190,556
Additions to property, plant and equipment	(136,328)	(95,822)
Proceeds from disposition of assets	104	0
Proceeds from sales and maturities of securities	26,859	0
Purchase of securities	(36,637)
Settlements of derivative instruments	(1,219)	(833)
Net cash used for investing activities	(147,221)	(96,655)
Intercompany financing	0	0
Dividends paid	(23,700)	(21,964)
Distributions paid	(3,985)	(3,558)
Proceeds from exercise of stock options	22	157
Proceeds from issuance of notes payable	2,050	0
Repayment of notes payable	(7,095)	0
Repurchase of common stock for treasury	(679)	(2,000)
Windfall tax benefits from share-based payment arrangements	266	1,701
Net cash provided by financing activities	(33,121)	(25,664)
Effect of exchange rate changes on cash and cash equivalents	3,858	(3,189)
Net (decrease) increase in cash and cash equivalents	(47,549)	65,048
Cash and cash equivalents at beginning of period	662,525	880,601
Cash and cash equivalents at end of period	614,976	945,649
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net income	123,128	146,342
Depreciation, Depletion and Amortization	220	501
Deferred income taxes	(2,724)	(124)
Net changes in working capital and other	(120,565)	(151,572)
Net cash provided by operating activities	59	(4,853)
Additions to property, plant and equipment	0	0
Proceeds from disposition of assets	0
Proceeds from sales and maturities of securities	26,859
Purchase of securities	(29,045)
Settlements of derivative instruments	0	0
Net cash used for investing activities	(2,186)	0
Intercompany financing	(13,763)	72,634
Dividends paid	(23,700)	(21,964)
Distributions paid	0	0
Proceeds from exercise of stock options	22	157
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	(679)	(2,000)
Windfall tax benefits from share-based payment arrangements	266	1,701
Net cash provided by financing activities	(37,854)	50,528
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	(39,981)	45,675
Cash and cash equivalents at beginning of period	303,131	655,947
Cash and cash equivalents at end of period	263,150	701,622
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	108,519	137,127
Depreciation, Depletion and Amortization	35,383	29,592
Deferred income taxes	59,139	6,431
Net changes in working capital and other	(188,331)	(114,779)
Net cash provided by operating activities	14,710	58,371
Additions to property, plant and equipment	(50,568)	(47,385)
Proceeds from disposition of assets	6
Proceeds from sales and maturities of securities	0
Purchase of securities	(7,592)
Settlements of derivative instruments	(1,219)	(833)
Net cash used for investing activities	(59,373)	(48,218)
Intercompany financing	(41,000)	(99,765)
Dividends paid	0	0
Distributions paid	79,999	89,161
Proceeds from exercise of stock options	0	0
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	0	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	38,999	(10,604)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	(5,664)	(451)
Cash and cash equivalents at beginning of period	6,828	3,057
Cash and cash equivalents at end of period	1,164	2,606
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Net income	104,570	89,343
Depreciation, Depletion and Amortization	20,396	19,803
Deferred income taxes	179	54
Net changes in working capital and other	(11,115)	6,973
Net cash provided by operating activities	114,030	116,173
Additions to property, plant and equipment	(79,091)	(39,540)
Proceeds from disposition of assets	98
Proceeds from sales and maturities of securities	0
Purchase of securities	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	(78,993)	(39,540)
Intercompany financing	59,519	30,191
Dividends paid	0	0
Distributions paid	(87,231)	(95,364)
Proceeds from exercise of stock options	0	0
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	0	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	(27,712)	(65,173)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	7,325	11,460
Cash and cash equivalents at beginning of period	163,430	131,545
Cash and cash equivalents at end of period	170,755	143,005
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	26,401	16,255
Depreciation, Depletion and Amortization	9,935	9,246
Deferred income taxes	2,043	(1,030)
Net changes in working capital and other	(38,243)	(3,606)
Net cash provided by operating activities	136	20,865
Additions to property, plant and equipment	(6,669)	(8,897)
Proceeds from disposition of assets	0
Proceeds from sales and maturities of securities	0
Purchase of securities	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	(6,669)	(8,897)
Intercompany financing	(4,756)	(3,060)
Dividends paid	0	0
Distributions paid	3,247	2,645
Proceeds from exercise of stock options	0	0
Proceeds from issuance of notes payable	2,050
Repayment of notes payable	(7,095)
Repurchase of common stock for treasury	0	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	(6,554)	(415)
Effect of exchange rate changes on cash and cash equivalents	3,858	(3,189)
Net (decrease) increase in cash and cash equivalents	(9,229)	8,364
Cash and cash equivalents at beginning of period	189,136	90,052
Cash and cash equivalents at end of period	179,907	98,416
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income	(233,682)	(238,660)
Depreciation, Depletion and Amortization	0	0
Deferred income taxes	0	0
Net changes in working capital and other	233,682	238,660
Net cash provided by operating activities	0	0
Additions to property, plant and equipment	0	0
Proceeds from disposition of assets	0
Proceeds from sales and maturities of securities	0
Purchase of securities	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	0	0
Intercompany financing	0	0
Dividends paid	0	0
Distributions paid	0	0
Proceeds from exercise of stock options	0	0
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	0	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$ 0	$ 0