10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-Q

x	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
	For the quarterly period ended September 30, 2015

or

¨	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
	For the Transition Period from                    to

Commission File No. 001-32260

Westlake Chemical Corporation

(Exact name of Registrant as specified in its charter)

Delaware	76-0346924
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

2801 Post Oak Boulevard, Suite 600

Houston, Texas 77056

(Address of principal executive offices, including zip code)

(713) 960-9111

(Registrant's telephone number, including area code)

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.     YesxNo¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).     YesxNo¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a smaller reporting company. See definitions of "large accelerated filer," "accelerated filer" and "smaller reporting company" in Rule 12b-2 of the Exchange Act (Check one):

Large accelerated filer	x	Accelerated filer	¨
Non-accelerated filer	¨  (Do not check if a smaller reporting company)	Smaller reporting company	¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act)     Yes¨Nox

The number of shares outstanding of the registrant's sole class of common stock as of October 28, 2015 was 130,652,184.

INDEX

Item	Page
PART I. FINANCIAL INFORMATION
1) Financial Statements	1
2) Management's Discussion and Analysis of Financial Condition and Results of Operations	31
3) Quantitative and Qualitative Disclosures about Market Risk	41
4) Controls and Procedures	42
PART II. OTHER INFORMATION
1) Legal Proceedings	43
1A) Risk Factors	43
2) Unregistered Sales of Equity Securities and Use of Proceeds	43
6) Exhibits	44

PART I. FINANCIAL INFORMATION

Item 1. Financial Statements

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED BALANCE SHEETS

(Unaudited)

	September 30, 2015			December 31, 2014
	(in thousands of dollars, except par values and share amounts)
ASSETS
Current assets
Cash and cash equivalents	$	961,925		$	880,601
Marketable securities	285,726			—
Accounts receivable, net	520,960			560,666
Inventories	430,006			525,776
Prepaid expenses and other current assets	18,272			11,807
Deferred income taxes	31,541			32,437
Total current assets	2,248,430			2,011,287
Property, plant and equipment, net	2,916,630			2,757,557
Equity investments	9,593			61,305
Other assets, net
Intangible assets, net	218,652			218,431
Deferred charges and other assets, net	131,100			165,410
Total other assets, net	349,752			383,841
Total assets	$	5,524,405		$	5,213,990
LIABILITIES AND EQUITY
Current liabilities
Accounts and notes payable	$	244,772		$	261,062
Accrued liabilities	290,115			276,118
Total current liabilities	534,887			537,180
Long-term debt	764,086			763,997
Deferred income taxes	534,824			536,066
Other liabilities	170,770			174,859
Total liabilities	2,004,567			2,012,102
Commitments and contingencies (Notes 8 and 19)
Stockholders' equity
Preferred stock, $0.01 par value, 50,000,000 shares authorized;    no shares issued and outstanding	—			—
Common stock, $0.01 par value, 300,000,000 shares authorized;    134,663,244 and 134,679,064 shares issued at September 30, 2015    and December 31, 2014, respectively	1,347			1,347
Common stock, held in treasury, at cost; 3,722,899 and 1,787,546 shares    at September 30, 2015 and December 31, 2014, respectively	(217,542		)	(96,372		)
Additional paid-in capital	540,342			530,441
Retained earnings	3,022,717			2,555,528
Accumulated other comprehensive loss	(121,865		)	(79,433		)
Total Westlake Chemical Corporation stockholders' equity	3,224,999			2,911,511
Noncontrolling interests	294,839			290,377
Total equity	3,519,838			3,201,888
Total liabilities and equity	$	5,524,405		$	5,213,990

The accompanying notes are an integral part of these consolidated financial statements.

1

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
	(in thousands of dollars, except per share data and share amounts)
Net sales	$	1,188,037		$	1,253,227		$	3,476,570		$	3,279,479
Cost of sales	876,761			891,707			2,527,567			2,324,978
Gross profit	311,276			361,520			949,003			954,501
Selling, general and administrative expenses	57,248			54,759			170,321			132,897
Income from operations	254,028			306,761			778,682			821,604
Other income (expense)
Interest expense	(8,211		)	(9,486		)	(26,760		)	(28,182		)
Other income (expense), net	2,636			(2,670		)	33,790			4,440
Income before income taxes	248,453			294,605			785,712			797,862
Provision for income taxes	60,033			124,449			236,824			300,231
Net income	188,420			170,156			548,888			497,631
Net income attributable to noncontrolling interests	4,816			2,399			13,847			2,399
Net income attributable to    Westlake Chemical Corporation	$	183,604		$	167,757		$	535,041		$	495,232
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.39		$	1.26		$	4.04		$	3.71
Diluted	$	1.39		$	1.25		$	4.02		$	3.69
Weighted average common shares outstanding:
Basic	131,664,296			133,299,458			132,301,814			133,199,304
Diluted	132,121,235			133,846,059			132,786,534			133,743,145
Dividends per common share	$	0.1815		$	0.1650		$	0.5115		$	0.4170

The accompanying notes are an integral part of these consolidated financial statements.

2

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(Unaudited)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
	(in thousands of dollars)
Net income	$	188,420		$	170,156		$	548,888		$	497,631
Other comprehensive (loss) income, net of income taxes
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves    adjustment (excluding amortization)	(22		)	(31		)	(208		)	(62		)
Amortization of benefits liability	692			240			2,019			685
Income tax provision on pension and other    post-retirement benefits liability	(232		)	(81		)	(621		)	(240		)
Foreign currency translation adjustments	(1,920		)	(37,792		)	(43,746		)	(37,882		)
Available-for-sale investments
Unrealized holding (losses) gains on    investments	(716		)	2,129			3,987			6,960
Reclassification of net realized gain to    net income	—			—			(3,795		)	(1,212		)
Income tax benefit (provision) on available-    for-sale investments	257			(766		)	(68		)	(2,066		)
Other comprehensive loss	(1,941		)	(36,301		)	(42,432		)	(33,817		)
Comprehensive income	186,479			133,855			506,456			463,814
Comprehensive income attributable to    noncontrolling interests, net of tax	4,816			2,399			13,847			2,399
Comprehensive income attributable to    Westlake Chemical Corporation	$	181,663		$	131,456		$	492,609		$	461,415

The accompanying notes are an integral part of these consolidated financial statements.

3

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

	Nine Months Ended September 30,
	2015			2014
	(in thousands of dollars)
Cash flows from operating activities
Net income	$	548,888		$	497,631
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	180,229			148,394
Provision for doubtful accounts	778			295
Amortization of debt issuance costs	1,504			1,172
Stock-based compensation expense	7,544			6,856
Loss from disposition of fixed assets	2,590			2,635
Gain from sales of securities	(3,795		)	—
Gain on acquisition, net of loss on the fair value remeasurement    of preexisting equity interest	(21,045		)	—
Impairment of equity method investment	4,925			—
Deferred income taxes	7,585			34,459
Windfall tax benefits from share-based payment arrangements	(2,452		)	(6,670		)
Income from equity method investments, net of dividends	(1,016		)	(3,199		)
Other losses (gains), net	3,584			(495		)
Changes in operating assets and liabilities
Accounts receivable	54,937			6,055
Inventories	105,899			80,492
Prepaid expenses and other current assets	(5,496		)	458
Accounts payable	(30,511		)	(98,769		)
Accrued liabilities	(10,893		)	111,965
Other, net	(1,955		)	(5,155		)
Net cash provided by operating activities	841,300			776,124
Cash flows from investing activities
Acquisition of business, net of cash acquired	15,782			(611,087		)
Additions to property, plant and equipment	(329,236		)	(311,183		)
Proceeds from disposition of assets	17			145
Proceeds from disposition of equity method investment	27,865			—
Proceeds from repayment of loan acquired	—			45,923
Proceeds from sales and maturities of securities	16,056			342,045
Purchase of securities	(282,542		)	(117,332		)
Settlements of derivative instruments	(1,535		)	(689		)
Net cash used for investing activities	(553,593		)	(652,178		)
Cash flows from financing activities
Capitalized debt issuance costs	—			(1,167		)
Dividends paid	(67,852		)	(55,690		)
Distributions to noncontrolling interests	(10,982		)	—
Net proceeds from issuance of Westlake Chemical Partners LP common units	—			286,088
Proceeds from exercise of stock options	984			5,502
Proceeds from issuance of notes payable	19,483			—
Repayment of notes payable	(32,954		)	—
Repurchase of common stock for treasury	(114,254		)	(9,495		)
Windfall tax benefits from share-based payment arrangements	2,452			6,670
Net cash (used for) provided by financing activities	(203,123		)	231,908
Effect of exchange rate changes on cash and cash equivalents	(3,260		)	(3,687		)
Net increase in cash and cash equivalents	81,324			352,167
Cash and cash equivalents at beginning of period	880,601			461,301
Cash and cash equivalents at end of period	$	961,925		$	813,468

The accompanying notes are an integral part of these consolidated financial statements.

4

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

1. Basis of Financial Statements

The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2014 financial statements and notes thereto of Westlake Chemical Corporation (the "Company") included in the annual report on Form 10-K for the fiscal year ended December 31, 2014 (the "2014 Form 10-K"), filed with the SEC on February 25, 2015. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Company for the fiscal year ended December 31, 2014.

In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of September 30, 2015, its results of operations for the three and nine months ended September 30, 2015 and 2014 and the changes in its cash position for the nine months ended September 30, 2015 and 2014.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2015 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Recent Accounting Pronouncements

Revenue from Contracts with Customers

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that will supersede the existing revenue recognition guidance. The new accounting guidance creates a framework by which an entity will allocate the transaction price to separate performance obligations and recognize revenue when each performance obligation is satisfied. Under the new standard, entities will be required to use judgment and make estimates, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price, allocating the transaction price to each separate performance obligation and determining when an entity satisfies its performance obligations. The standard allows for either "full retrospective" adoption, meaning that the standard is applied to all of the periods presented with a cumulative catch-up as of the earliest period presented, or "modified retrospective" adoption, meaning the standard is applied only to the most current period presented in the financial statements with a cumulative catch-up as of the current period. In July 2015, the FASB deferred the effective date for the revenue recognition standard. The accounting standard will now be effective for reporting periods beginning after December 15, 2017. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows.

Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items

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

5

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Amendments to the Consolidation Analysis

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

Simplifying the Presentation of Debt Issuance Costs

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

Simplifying the Measurement of Inventory

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

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

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

Simplifying the Accounting for Measurement-Period Adjustments

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

6

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

2. Financial Instruments

Cash Equivalents

The Company had $530,806 and $509,811 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at September 30, 2015 and December 31, 2014, 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:

	September 30, 2015		December 31, 2014
Current	$	285,726	$	—
Non-current	4,098		15,414
Total available-for-sale securities	$	289,824	$	15,414

The cost, gross unrealized gains, gross unrealized losses and fair value of the Company's available-for-sale securities were as follows:

	September 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Debt securities
Corporate bonds	$	194,310	$	306	$	(171	)	$	194,445
U.S. government debt	55,073		80		(2		)	55,151
Asset-backed securities	36,081		66		(17		)	36,130
Equity securities	3,804		294		—			4,098
Total available-for-sale securities	$	289,268	$	746	$	(190	)	$	289,824

	December 31, 2014
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	15,050	$	364	$	—	$	15,414
Total available-for-sale securities	$	15,050	$	364	$	—	$	15,414

As of September 30, 2015 and December 31, 2014, net unrealized gains on the Company's available-for-sale securities of $357 and $233, respectively, net of income tax expense of $199 and $131, respectively, were recorded in accumulated other comprehensive income. See Note 13 for the fair value hierarchy of the Company's available-for-sale securities.

As of September 30, 2015, the corporate bond securities held by the Company had maturities ranging between two months to three years, the U.S. government debt securities held by the Company, excluding U.S. government agency mortgage-backed securities, had maturities ranging between four months to three years, the U.S. government agency mortgage-backed securities held by the Company had maturities ranging between five to six years and the asset-backed securities held by the Company had maturities ranging between one to 26 years.

7

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

The proceeds from sales and maturities of available-for-sale securities and the gross realized gains and losses included in the consolidated statements of operations are reflected in the table below. The cost of securities sold was determined using the specific identification method.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Proceeds from sales and maturities of securities	$	1,019	$	—	$	16,056	$	342,045
Gross realized gains	—		—		3,795		1,311
Gross realized losses	—		—		—		(99		)

3. Accounts Receivable

Accounts receivable consist of the following:

	September 30, 2015			December 31, 2014
Trade customers	$	495,318		$	525,546
Affiliates	—			437
Allowance for doubtful accounts	(13,967		)	(13,468		)
	481,351			512,515
Federal and state taxes	19,819			8,919
Other	19,790			39,232
Accounts receivable, net	$	520,960		$	560,666

4. Inventories

Inventories consist of the following:

	September 30, 2015		December 31, 2014
Finished products	$	238,671	$	300,909
Feedstock, additives and chemicals	118,498		158,635
Materials and supplies	72,837		66,232
Inventories	$	430,006	$	525,776

5. Property, Plant and Equipment

As of September 30, 2015, the Company had property, plant and equipment, net totaling $2,916,630. 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 $52,208 and $45,080 is included in cost of sales in the consolidated statements of operations for the three months ended September 30, 2015 and 2014, respectively. Depreciation expense on property, plant and equipment of $153,129 and $123,000 is included in cost of sales in the consolidated statements of operations for the nine months ended September 30, 2015 and 2014, respectively.

8

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

6. Other Assets

Amortization expense on intangible and other assets of $9,542 and $9,283 is included in the consolidated statements of operations for the three months ended September 30, 2015 and 2014, respectively. Amortization expense on intangible and other assets of $28,604 and $26,566 is included in the consolidated statements of operations for the nine months ended September 30, 2015 and 2014, respectively.

Goodwill

Goodwill for the Olefins segment was $29,990 at September 30, 2015 and December 31, 2014. Goodwill for the Vinyls segment was $32,026 at September 30, 2015 and December 31, 2014. There were no changes in the carrying amount of goodwill by operating segments for the nine months ended September 30, 2015.

7. Accounts and Notes Payable

Accounts and notes payable consist of the following:

	September 30, 2015		December 31, 2014
Accounts payable	$	237,622	$	261,062
Notes payable to banks	7,150		—
Accounts and notes payable	$	244,772	$	261,062

8. Long-Term Debt

Long-term debt consists of the following:

	September 30, 2015		December 31, 2014
3.60% senior notes due 2022	$	249,197	$	249,108
6 ½% senior notes due 2029	100,000		100,000
6 ¾% senior notes due 2032	250,000		250,000
6 ½% senior notes due 2035 (the "6 ½% GO Zone Senior Notes Due 2035")	89,000		89,000
6 ½% senior notes due 2035 (the "6 ½% IKE Zone Senior Notes Due 2035")	65,000		65,000
Loan related to tax-exempt waste disposal revenue bonds due 2027	10,889		10,889
Long-term debt, net	$	764,086	$	763,997

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 September 30, 2015, 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 September 30, 2015, the Company had outstanding letters of credit totaling $29,953 and borrowing availability of $346,374 under the revolving credit facility.

9

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

9. Stockholders' Equity

Changes in stockholders' equity for the nine months ended September 30, 2015 and 2014 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, 2014	$	1,347	$	(96,372	)	$	530,441		$	2,555,528		$	(79,433	)	$	290,377		$	3,201,888
Net income	—		—			—			535,041			—			13,847			548,888
Other comprehensive income    (loss), net of income taxes:
Pension and other post-    retirement benefits    liability	—		—			—			—			1,190			—			1,190
Foreign currency    translation adjustments	—		—			—			—			(43,746		)	—			(43,746		)
Net unrealized holding    gains on investments	—		—			—			—			124			—			124
Common stock repurchased	—		(122,249		)	—			—			—			—			(122,249		)
Shares issued—stock-    based compensation	—		1,079			(95		)	—			—			—			984
Stock-based compensation,    net of tax on stock options    exercised	—		—			9,996			—			—			—			9,996
Dividends paid	—		—			—			(67,852		)	—			—			(67,852		)
Distributions to noncontrolling    interests	—		—			—			—			—			(10,982		)	(10,982		)
Noncontrolling interest in    acquired business	—		—			—			—			—			1,597			1,597
Balances at September 30, 2015	$	1,347	$	(217,542	)	$	540,342		$	3,022,717		$	(121,865	)	$	294,839		$	3,519,838

	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, 2013	$	1,346	$	(46,220	)	$	511,432	$	1,954,661		$	(2,616	)	$	—	$	2,418,603
Net income	—		—			—		495,232			—			2,399		497,631
Other comprehensive income    (loss), net of income taxes
Pension and other post-    retirement benefits    liability	—		—			—		—			383			—		383
Foreign currency    translation adjustments	—		—			—		—			(37,882		)	—		(37,882		)
Net unrealized holding    gains on investments	—		—			—		—			3,682			—		3,682
Common stock repurchased	—		(9,495		)	—		—			—			—		(9,495		)
Shares issued—stock-    based compensation	1		2,467			3,034		—			—			—		5,502
Stock-based compensation,    net of tax on stock options    exercised	—		—			13,526		—			—			—		13,526
Dividends paid	—		—			—		(55,690		)	—			—		(55,690		)
Issuance of Westlake Chemical    Partners LP common units	—		—			—		—			—			286,088		286,088
Balances at September 30, 2014	$	1,347	$	(53,248	)	$	527,992	$	2,394,203		$	(36,433	)	$	288,487	$	3,122,348

10

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive income (loss) by component for the nine months ended September 30, 2015 and 2014 were as follows:

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2014	$	(23,442	)	$	(56,224	)	$	233		$	(79,433	)
Other comprehensive (loss) income before    reclassifications	(128		)	(43,746		)	2,556			(41,318		)
Amounts reclassified from accumulated other    comprehensive loss (income)	1,318			—			(2,432		)	(1,114		)
Net other comprehensive income (loss) for the period	1,190			(43,746		)	124			(42,432		)
Balances at September 30, 2015	$	(22,252	)	$	(99,970	)	$	357		$	(121,865	)

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2013	$	(6,696	)	$	3,904		$	176		$	(2,616	)
Other comprehensive (loss) income before    reclassifications	(39		)	(37,882		)	4,459			(33,462		)
Amounts reclassified from accumulated other    comprehensive loss (income)	422			—			(777		)	(355		)
Net other comprehensive income (loss) for the period	383			(37,882		)	3,682			(33,817		)
Balances at September 30, 2014	$	(6,313	)	$	(33,978	)	$	3,858		$	(36,433	)

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 and nine months ended September 30, 2015 and 2014:

Details about Accumulated    Other Comprehensive    Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Three Months Ended September 30,						Nine Months Ended September 30,
		2015			2014			2015			2014
Amortization of pension and    other post-retirement items
Prior service costs	(1)	$	—		$	(87	)	$	—		$	(261	)
Net loss	(1)	(692		)	(153		)	(2,019		)	(424		)
		(692		)	(240		)	(2,019		)	(685		)
	Provision for income    taxes	241			92			701			263
		(451		)	(148		)	(1,318		)	(422		)
Net unrealized gains on    available-for-sale    investments
Realized gain on    available-for-sale    investments	Other income    (expense), net	—			—			3,795			1,212
	Provision for income    taxes	—			—			(1,363		)	(435		)
		—			—			2,432			777
Total reclassifications for    the period		$	(451	)	$	(148	)	$	1,114		$	355

11

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

_____________

(1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 10 (Employee Benefits) to the financial statements included in the 2014 Form 10-K.

10. 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 September 30,										Nine Months Ended September 30,
	2015					2014					2015					2014
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Service cost	$	—		$	416	$	83		$	248	$	29		$	1,248	$	250		$	248
Interest cost	487			528		576			562		1,519			1,585		1,747			562
Expected return on plan assets	(712		)	—		(777		)	—		(2,237		)	—		(2,363		)	—
Amortization of prior    service cost	—			—		74			—		—			—		223			—
Amortization of net loss	333			263		71			—		942			789		204			—
Net periodic benefit cost	$	108		$	1,207	$	27		$	810	$	253		$	3,622	$	61		$	810

The Company made no contribution to the U.S. salaried pension plan in the first nine months of 2015. The Company contributed $2,447 to the U.S. salaried pension plan in the first nine months of 2014. The Company contributed $349 and $916 to the U.S. wage pension plan in the first nine months of 2015 and 2014, respectively. 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 no contribution for the salaried pension plan and no further contribution to the wage pension plan for the fiscal year ending December 31, 2015.

Other Post-retirement Benefits

Components of net periodic benefit cost for the Company's other post-retirement benefits are as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
	U.S. Plans		U.S. Plans		U.S. Plans		U.S. Plans
Service cost	$	6	$	6	$	17	$	16
Interest cost	149		185		448		548
Amortization of prior service cost	—		13		—		38
Amortization of net loss	96		82		288		220
Net periodic benefit cost	$	251	$	286	$	753	$	822

11. 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 $2,639 and $2,346 for the three months ended September 30, 2015 and 2014,respectively, and $7,544 and $6,856 for the nine months ended September 30, 2015 and 2014, respectively.

12

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

12. 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.

For derivative instruments that are designated and qualify as fair value hedges, the gains or losses on the derivative instruments, as well as the offsetting losses or gains on the hedged items attributable to the hedged risk, are included in cost of sales in the consolidated statement of operations. The Company had no derivative instruments that were designated as fair value hedges for the nine months ended September 30, 2015 and 2014.

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 and nine months ended September 30, 2015 and 2014.

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).

Disclosures related to the Company's derivative assets and derivative liabilities subject to enforceable master netting arrangements have not been presented as they are not material to the Company's consolidated balance sheets at September 30, 2015 and December 31, 2014.

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
		September 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	2,722	$	3,145
Commodity forward contracts	Deferred charges and    other assets, net	2,017		—
Total derivative assets		$	4,739	$	3,145

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		September 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	5,421	$	6,549
Commodity forward contracts	Other liabilities	9,846		3,559
Total derivative liabilities		$	15,267	$	10,108

13

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

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 September 30,						Nine Months Ended September 30,
		2015			2014			2015			2014
Commodity forward contracts	Gross profit	$	(9,314	)	$	(6,937	)	$	(4,478	)	$	(7,308	)

See Note 13 for the fair value of the Company's derivative instruments.

13. 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:

	September 30, 2015
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	4,700		$	39		$	4,739
Risk management liabilities—Commodity forward contracts	(8,395		)	(6,872		)	(15,267		)
Marketable securities
Available-for-sale securities	57,733			232,091			289,824
	December 31, 2014
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	3,143		$	2		$	3,145
Risk management liabilities—Commodity forward contracts	—			(10,108		)	(10,108		)
Marketable securities
Available-for-sale securities	15,414			—			15,414

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 nine months ended September 30, 2015 and 2014.

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

14

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

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.

	September 30, 2015				December 31, 2014
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	249,197	$	246,843	$	249,108	$	248,630
6 ½% senior notes due 2029	100,000		116,663		100,000		116,384
6 ¾% senior notes due 2032	250,000		273,655		250,000		285,545
6 ½% GO Zone Senior Notes Due 2035	89,000		103,740		89,000		106,504
6 ½% IKE Zone Senior Notes Due 2035	65,000		74,719		65,000		77,784
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

14. Income Taxes

The effective income tax rate was 24.2% for the three months ended September 30, 2015. The effective income tax rate for the three months ended September 30, 2015 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, the foreign earnings rate differential, the increased benefit in certain prior years' deductions due to a change in the calculation methodology of the domestic manufacturing deduction and adjustments related to prior years' tax returns as filed, partially offset by state income taxes. The effective income tax rate was 42.2% for the three months ended September 30, 2014. The effective income tax rate for the three months ended September 30, 2014 was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.

The effective income tax rate was 30.1% for the nine months ended September 30, 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, the non-recognition of tax related to the bargain purchase of a controlling interest in Suzhou Huasu Plastics Co., Ltd., the increased benefit in certain prior years' deductions due to a change in the calculation methodology of the domestic manufacturing deduction and adjustments related to prior years' tax returns as filed and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 37.6% for the nine months ended September 30, 2014. The effective income tax rate for the 2014 period was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.

There were no unrecognized tax benefits for the nine months ended September 30, 2015. The Company recognizes penalties and interest accrued related to unrecognized tax benefits in income tax expense. As of September 30, 2015, 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.

15. 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 September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Net income attributable to    Westlake Chemical Corporation	$	183,604		$	167,757		$	535,041		$	495,232
Less:
Net income attributable to participating securities	(195		)	(353		)	(653		)	(1,099		)
Net income attributable to common shareholders	$	183,409		$	167,404		$	534,388		$	494,133

15

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

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 September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Weighted average common shares—basic	131,664,296		133,299,458		132,301,814		133,199,304
Plus incremental shares from:
Assumed exercise of options	456,939		546,601		484,720		543,841
Weighted average common shares—diluted	132,121,235		133,846,059		132,786,534		133,743,145
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.39	$	1.26	$	4.04	$	3.71
Diluted	$	1.39	$	1.25	$	4.02	$	3.69

Excluded from the computation of diluted earnings per share are options to purchase 315,285 and 295,825 shares of common stock for the three and nine months ended September 30, 2015, respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive. There were no options excluded from the computation of diluted earnings per share for the three and nine months ended September 30, 2014.

16. Supplemental Information

Accrued Liabilities

Accrued liabilities were $290,115 and $276,118 at September 30, 2015 and December 31, 2014, respectively. Accrued rebates and accrued incentive compensation, which are components of accrued liabilities, were $39,046 and $43,151 at September 30, 2015, respectively, and $49,900 and $37,626 at December 31, 2014, respectively. No other component of accrued liabilities was more than five percent of total current liabilities.

Other Liabilities

Other liabilities were $170,770 and $174,859 at September 30, 2015 and December 31, 2014, respectively. Non-current pension obligation, which is a component of other liabilities, was $127,235 and $136,296 at September 30, 2015 and December 31, 2014, respectively. No other component of other liabilities was more than five percent of total liabilities.

Other Income (Expense), Net

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Interest income	$	1,631		$	341		$	3,383		$	2,669
Dividend income	—			—			3,328			—
Foreign exchange currency (losses) gains, net	(731		)	(6,450		)	1,140			(6,695		)
Income from equity method investments	664			3,304			5,278			7,244
Impairment of equity method investment	—			—			(4,925		)	—
Gain on acquisition and related expenses, net	—			—			20,430			—
Gain from sales of equity securities	—			—			3,795			—
Other	1,072			135			1,361			1,222
Other income (expense), net	$	2,636		$	(2,670	)	$	33,790		$	4,440

16

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

17. Acquisition

On June 1, 2015, the Company acquired an additional 35.7% equity interest in Suzhou Huasu Plastics Co., Ltd. ("Huasu") from INEOS Chlor Vinyls Holdings B.V., increasing its interest in Huasu to 95.0%. Huasu is a polyvinyl chloride ("PVC") joint venture based near Shanghai, People's Republic of China and has a combined annual capacity of 300 million pounds of PVC resin, 145 million pounds of PVC film and sheet and 33 million pounds of building products.

Prior to the acquisition of this 35.7% interest, the Company owned a 59.3% interest in Huasu. The Company accounted for the investment using the equity method of accounting because Huasu did not meet the definition of a variable interest entity and because contractual arrangements giving certain substantive participatory rights to minority shareholders prevented the Company from exercising a controlling financial interest over Huasu. As a result of the Company obtaining control over Huasu, the Company's 59.3% interest was remeasured to fair value, resulting in a loss of $1,505, which is included in other income (expense), net in the consolidated statements of operations.

The closing date purchase price of $5,518 was paid with available cash on hand. The acquisition is being accounted for under the acquisition method of accounting. The transaction resulted in a bargain purchase acquisition-date gain of $22,550 and is recognized in other income (expense), net in the consolidated statements of operations. The Company believes there are several factors that contributed to this transaction resulting in a bargain purchase acquisition-date gain, including the slowdown in the growth of, and current weakness in, the Chinese economy. The assets acquired and liabilities assumed and the results of operations of this acquired business are included in the Vinyls segment. Huasu's net sales and earnings included in the consolidated statements of operations since the acquisition date have not been presented separately as they are not material to the Company's consolidated statements of operations for the three and nine months ended September 30, 2015. The acquisition-related costs recognized in the consolidated statements of operations for the three and nine months ended September 30, 2015 are not material. The pro forma impact of this business combination has not been presented as it is not material to the Company's consolidated statements of operations for the nine months ended September 30, 2015 and 2014.

The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition. The final determination of fair value for certain assets and liabilities will be completed as soon as the information necessary to complete the analysis is obtained. These amounts will be finalized as soon as possible, but no later than one year from the acquisition date.

Fair value of consideration transferred—cash	$	5,518
Preexisting balances between the Company and Huasu, net	(8,538		)
Fair value of the Company's investment in Huasu before the business combination (1)	18,890
Fair value of the noncontrolling interest in Huasu (1)	1,597
	$	17,467
Preliminary allocation of consideration transferred to net assets acquired:
Cash	$	21,300
Working capital, excluding inventory and cash (2)	(5,461		)
Inventories	17,717
Property, plant and equipment	19,786
Other assets	7,760
Notes payable to banks	(21,085		)
Total identifiable net assets	40,017
Bargain purchase gain on acquisition	$	22,550

_____________

(1) The fair values of the Company's 59.3% equity interest and the noncontrolling interest were estimated using internally developed, unobservable inputs (Level 3 inputs in the fair value hierarchy of fair value accounting) based on a cost approach.

(2) The fair value of accounts receivable acquired is $2,515, with the gross contractual amount being $3,006. The Company expects $491 to be uncollectible.

17

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

18. 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. For the three and nine months ended September 30, 2015, the Company recognized approximately $3,347 and $7,809, respectively, as a partial insurance recovery related to business interruption costs, primarily for additional costs incurred to procure the necessary feedstock and other costs as a result of the fire at the third-party facility. The partial insurance recovery is included in cost of sales in the consolidated statements of operations.

19. 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 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 $2,805 in 2014. 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 seeks to readjust the percentage allocation of costs and to recover approximately $1,400 from the Company in reimbursement of previously paid remediation costs. The arbitration is currently stayed.

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

18

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

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. Such global settlement may result in a total civil penalty of approximately $200.

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.

19

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

20. 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 September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Net external sales
Olefins
Polyethylene	$	423,631		$	498,450		$	1,283,545		$	1,461,097
Styrene, feedstock and other	164,466			204,647			508,507			663,851
Total Olefins	588,097			703,097			1,792,052			2,124,948
Vinyls
PVC, caustic soda and other	468,235			416,771			1,315,101			776,060
Building products	131,705			133,359			369,417			378,471
Total Vinyls	599,940			550,130			1,684,518			1,154,531
	$	1,188,037		$	1,253,227		$	3,476,570		$	3,279,479
Intersegment sales
Olefins	$	28,551		$	26,518		$	78,654		$	118,153
Vinyls	341			355			1,098			1,029
	$	28,892		$	26,873		$	79,752		$	119,182
Income (loss) from operations
Olefins	$	196,703		$	259,277		$	608,744		$	770,267
Vinyls	67,779			59,445			202,831			76,460
Corporate and other	(10,454		)	(11,961		)	(32,893		)	(25,123		)
	$	254,028		$	306,761		$	778,682		$	821,604
Depreciation and amortization
Olefins	$	27,678		$	26,443		$	82,240		$	79,811
Vinyls	33,432			27,336			97,615			68,127
Corporate and other	138			141			374			456
	$	61,248		$	53,920		$	180,229		$	148,394
Other income (expense), net
Olefins	$	1,323		$	1,609		$	3,770		$	4,262
Vinyls	10			1,189			6,927			942
Corporate and other	1,303			(5,468		)	23,093			(764		)
	$	2,636		$	(2,670	)	$	33,790		$	4,440
Provision for (benefit from) income taxes
Olefins	$	45,865		$	105,030		$	186,534		$	282,082
Vinyls	15,812			21,761			55,270			22,121
Corporate and other	(1,644		)	(2,342		)	(4,980		)	(3,972		)
	$	60,033		$	124,449		$	236,824		$	300,231
Capital expenditures
Olefins	$	69,885		$	48,519		$	206,719		$	121,041
Vinyls	53,510			44,067			114,935			187,449
Corporate and other	1,909			1,685			7,582			2,693
	$	125,304		$	94,271		$	329,236		$	311,183

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Income from operations	$	254,028		$	306,761		$	778,682		$	821,604
Interest expense	(8,211		)	(9,486		)	(26,760		)	(28,182		)
Other income (expense), net	2,636			(2,670		)	33,790			4,440
Income before income taxes	$	248,453		$	294,605		$	785,712		$	797,862

	September 30, 2015		December 31, 2014
Total assets
Olefins	$	1,817,303	$	1,785,895
Vinyls	2,601,263		2,618,646
Corporate and other	1,105,839		809,449
	$	5,524,405	$	5,213,990

21. Subsequent Events

Subsequent events were evaluated through the date on which the financial statements were issued.

22. 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. OpCo has been presented as a less than 100% owned guarantor subsidiary in each of the tables below, including for periods prior to the initial public offering of Westlake Partners. 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.

20

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information as of September 30, 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	$	647,646	$	5,445	$	149,482	$	159,352	$	—		$	961,925
Marketable securities	285,726		—		—		—		—			285,726
Accounts receivable, net	9,371		2,165,248		58,514		135,837		(1,848,010		)	520,960
Inventories	—		333,553		3,272		93,181		—			430,006
Prepaid expenses and other current assets	1,355		15,244		382		3,576		(2,285		)	18,272
Deferred income taxes	441		30,529		—		647		(76		)	31,541
Total current assets	944,539		2,550,019		211,650		392,593		(1,850,371		)	2,248,430
Property, plant and equipment, net	—		1,533,456		962,221		420,953		—			2,916,630
Equity investments	4,879,268		1,204,734		—		468,760		(6,543,169		)	9,593
Other assets, net	17,541		353,506		46,542		133,196		(201,033		)	349,752
Total assets	$	5,841,348	$	5,641,715	$	1,220,413	$	1,415,502	$	(8,594,573	)	$	5,524,405
Current liabilities
Accounts and notes payable	$	1,847,047	$	131,438	$	33,476	$	80,685	$	(1,847,874	)	$	244,772
Accrued liabilities	16,105		168,569		21,055		86,883		(2,497		)	290,115
Total current liabilities	1,863,152		300,007		54,531		167,568		(1,850,371		)	534,887
Long-term debt	753,197		10,889		195,154		—		(195,154		)	764,086
Deferred income taxes	—		503,102		1,489		36,112		(5,879		)	534,824
Other liabilities	—		49,174		—		121,596		—			170,770
Total liabilities	2,616,349		863,172		251,174		325,276		(2,051,404		)	2,004,567
Total Westlake Chemical Corporation stockholders' equity	3,224,999		4,778,543		969,239		795,387		(6,543,169		)	3,224,999
Noncontrolling interests	—		—		—		294,839		—			294,839
Total equity	3,224,999		4,778,543		969,239		1,090,226		(6,543,169		)	3,519,838
Total liabilities and equity	$	5,841,348	$	5,641,715	$	1,220,413	$	1,415,502	$	(8,594,573	)	$	5,524,405

21

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information as of December 31, 2014

	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	$	655,947	$	3,057	$	131,545	$	90,052	$	—		$	880,601
Accounts receivable, net	8,451		1,454,709		56,049		135,133		(1,093,676		)	560,666
Inventories	—		414,975		6,634		104,167		—			525,776
Prepaid expenses and other current assets	172		9,485		212		1,938		—			11,807
Deferred income taxes	409		29,832		—		2,196		—			32,437
Total current assets	664,979		1,912,058		194,440		333,486		(1,093,676		)	2,011,287
Property, plant and equipment, net	—		1,477,515		842,057		437,985		—			2,757,557
Equity investments	4,033,378		1,237,080		—		352,550		(5,561,703		)	61,305
Other assets, net	30,543		387,325		57,733		141,948		(233,708		)	383,841
Total assets	$	4,728,900	$	5,013,978	$	1,094,230	$	1,265,969	$	(6,889,087	)	$	5,213,990
Current liabilities
Accounts payable	$	1,055,527	$	160,834	$	17,680	$	95,856	$	(1,068,835	)	$	261,062
Accrued liabilities	8,754		203,608		11,225		77,372		(24,841		)	276,118
Total current liabilities	1,064,281		364,442		28,905		173,228		(1,093,676		)	537,180
Long-term debt	753,108		10,889		227,638		—		(227,638		)	763,997
Deferred income taxes	—		497,919		1,848		42,369		(6,070		)	536,066
Other liabilities	—		43,452		—		131,407		—			174,859
Total liabilities	1,817,389		916,702		258,391		347,004		(1,327,384		)	2,012,102
Total Westlake Chemical Corporation stockholders' equity	2,911,511		4,097,276		835,839		628,588		(5,561,703		)	2,911,511
Noncontrolling interests	—		—		—		290,377		—			290,377
Total equity	2,911,511		4,097,276		835,839		918,965		(5,561,703		)	3,201,888
Total liabilities and equity	$	4,728,900	$	5,013,978	$	1,094,230	$	1,265,969	$	(6,889,087	)	$	5,213,990

22

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information for the Three Months Ended September 30, 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	$	—		$	961,036		$	248,619		$	288,211		$	(309,829	)	$	1,188,037
Cost of sales	—			774,726			154,474			252,618			(305,057		)	876,761
Gross profit	—			186,310			94,145			35,593			(4,772		)	311,276
Selling, general and administrative expenses	804			41,429			4,941			14,846			(4,772		)	57,248
(Loss) income from operations	(804		)	144,881			89,204			20,747			—			254,028
Interest expense	(10,405		)	(3		)	(217		)	(95		)	2,509			(8,211		)
Other income (expense), net	1,239			3,971			(124		)	59			(2,509		)	2,636
(Loss) income before income taxes	(9,970		)	148,849			88,863			20,711			—			248,453
(Benefit from) provision for income taxes	(3,249		)	56,372			141			6,769			—			60,033
Equity in net income of subsidiaries	190,325			76,945			—			11,777			(279,047		)	—
Net income	183,604			169,422			88,722			25,719			(279,047		)	188,420
Net income attributable to noncontrolling interests	—			—			—			4,816			—			4,816
Net income attributable to Westlake Chemical Corporation	$	183,604		$	169,422		$	88,722		$	20,903		$	(279,047	)	$	183,604
Comprehensive income attributable to    Westlake Chemical Corporation	$	181,663		$	169,673		$	88,722		$	19,170		$	(277,565	)	$	181,663

23

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information for the Three Months Ended September 30, 2014

	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			OpCo (Less Than 100% Owned Guarantor Subsidiary)			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	1,026,282		$	392,008		$	208,313		$	(373,376	)	$	1,253,227
Cost of sales	—			831,675			227,015			202,110			(369,093		)	891,707
Gross profit	—			194,607			164,993			6,203			(4,283		)	361,520
Selling, general and administrative expenses	399			36,445			8,014			14,184			(4,283		)	54,759
(Loss) income from operations	(399		)	158,162			156,979			(7,981		)	—			306,761
Interest expense	(10,343		)	(2		)	(2,137		)	(39		)	3,035			(9,486		)
Other income (expense), net	2,138			(2,942		)	486			683			(3,035		)	(2,670		)
(Loss) income before income taxes	(8,604		)	155,218			155,328			(7,337		)	—			294,605
(Benefit from) provision for income taxes	(3,088		)	93,366			36,309			(2,138		)	—			124,449
Equity in net income of subsidiaries	173,273			113,157			—			5,862			(292,292		)	—
Net income	167,757			175,009			119,019			663			(292,292		)	170,156
Net income attributable to noncontrolling interests	—			—			—			2,399			—			2,399
Net income (loss) attributable to Westlake Chemical Corporation	$	167,757		$	175,009		$	119,019		$	(1,736	)	$	(292,292	)	$	167,757
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	131,456		$	175,137		$	119,019		$	(39,528	)	$	(254,628	)	$	131,456

24

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 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	$	—		$	2,862,400		$	758,715		$	784,219		$	(928,764	)	$	3,476,570
Cost of sales	—			2,260,454			473,815			707,171			(913,873		)	2,527,567
Gross profit	—			601,946			284,900			77,048			(14,891		)	949,003
Selling, general and administrative expenses	1,617			127,794			15,178			40,623			(14,891		)	170,321
(Loss) income from operations	(1,617		)	474,152			269,722			36,425			—			778,682
Interest expense	(31,726		)	(8		)	(2,449		)	(190		)	7,613			(26,760		)
Other income (expense), net	17,627			(2,574		)	(85		)	26,435			(7,613		)	33,790
(Loss) income before income taxes	(15,716		)	471,570			267,188			62,670			—			785,712
(Benefit from) provision for income taxes	(5,226		)	231,542			567			9,941			—			236,824
Equity in net income of subsidiaries	545,531			233,635			—			32,986			(812,152		)	—
Net income	535,041			473,663			266,621			85,715			(812,152		)	548,888
Net income attributable to noncontrolling interests	—			—			—			13,847			—			13,847
Net income attributable to Westlake Chemical Corporation	$	535,041		$	473,663		$	266,621		$	71,868		$	(812,152	)	$	535,041
Comprehensive income attributable to    Westlake Chemical Corporation	$	492,609		$	474,292		$	266,621		$	28,683		$	(769,596	)	$	492,609

25

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2014

	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			OpCo (Less Than 100% Owned Guarantor Subsidiary)			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	2,809,844		$	1,476,157		$	229,183		$	(1,235,705	)	$	3,279,479
Cost of sales	—			2,476,608			832,304			221,233			(1,205,167		)	2,324,978
Gross profit	—			333,236			643,853			7,950			(30,538		)	954,501
Selling, general and administrative expenses	1,474			123,050			21,957			16,954			(30,538		)	132,897
(Loss) income from operations	(1,474		)	210,186			621,896			(9,004		)	—			821,604
Interest expense	(29,032		)	(8		)	(9,833		)	(39		)	10,730			(28,182		)
Other income (expense), net	14,488			(1,729		)	3,135			(724		)	(10,730		)	4,440
(Loss) income before income taxes	(16,018		)	208,449			615,198			(9,767		)	—			797,862
(Benefit from) provision for income taxes	(5,686		)	109,920			198,461			(2,464		)	—			300,231
Equity in net income of subsidiaries	505,564			410,875			—			5,862			(922,301		)	—
Net income (loss)	495,232			509,404			416,737			(1,441		)	(922,301		)	497,631
Net income attributable to noncontrolling interests	—			—			—			2,399			—			2,399
Net income (loss) attributable to Westlake Chemical Corporation	$	495,232		$	509,404		$	416,737		$	(3,840	)	$	(922,301	)	$	495,232
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	461,415		$	509,787		$	416,737		$	(41,722	)	$	(884,802	)	$	461,415

26

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 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	$	535,041		$	473,663		$	266,621		$	85,715		$	(812,152	)	$	548,888
Adjustments to reconcile net income to net cash (used for)    provided by operating activities
Depreciation and amortization	1,504			90,247			60,637			29,345			—			181,733
Deferred income taxes	87			4,184			(359		)	3,673			—			7,585
Net changes in working capital and other	(567,137		)	(251,423		)	9,315			100,187			812,152			103,094
Net cash (used for) provided by operating activities	(30,505		)	316,671			336,214			218,920			—			841,300
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			—			—			15,782			—			15,782
Additions to property, plant and equipment	—			(148,055		)	(152,572		)	(28,609		)	—			(329,236		)
Proceeds from disposition of assets	—			—			—			17			—			17
Proceeds from disposition of equity method investment	—			27,865			—			—			—			27,865
Proceeds from sales and maturities of securities	16,056			—			—			—			—			16,056
Purchase of securities	(282,542		)	—			—			—			—			(282,542		)
Settlements of derivative instruments	—			(1,535		)	—			—			—			(1,535		)
Net cash used for investing activities	(266,486		)	(121,725		)	(152,572		)	(12,810		)	—			(553,593		)
Cash flows from financing activities
Intercompany financing	467,360			(577,898		)	102,857			7,681			—			—
Intercompany financing—OpCo	—			135,341			(135,341		)	—			—			—
Dividends paid	(67,852		)	—			—			—			—			(67,852		)
Distributions paid	—			249,999			(268,562		)	7,581			—			(10,982		)
Purchase of limited partner interests	—			—			135,341			(135,341		)	—			—
Proceeds from exercise of stock options	984			—			—			—			—			984
Proceeds from issuance of notes payable	—			—			—			19,483			—			19,483
Repayment of notes payable	—			—			—			(32,954		)	—			(32,954		)
Repurchase of common stock for treasury	(114,254		)	—			—			—			—			(114,254		)
Windfall tax benefits from share-based payment arrangements	2,452			—			—			—			—			2,452
Net cash provided by (used for) financing activities	$	288,690		$	(192,558	)	$	(165,705	)	$	(133,550	)	$	—		$	(203,123	)

27

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries		OpCo (Less Than 100% Owned Guarantor Subsidiary)		Non- Guarantor Subsidiaries			Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	$	—		$	—	$	—	$	(3,260	)	$	—	$	(3,260	)
Net (decrease) increase in cash and cash equivalents	(8,301		)	2,388		17,937		69,300			—		81,324
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	$	647,646		$	5,445	$	149,482	$	159,352		$	—	$	961,925

28

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2014

	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 (loss)	$	495,232		$	509,404		$	416,737		$	(1,441	)	$	(922,301	)	$	497,631
Adjustments to reconcile net income (loss) to net cash (used for)    provided by operating activities
Depreciation and amortization	1,172			82,597			58,501			7,296			—			149,566
Deferred income taxes	(418		)	26,991			8,267			(381		)	—			34,459
Net changes in working capital and other	(509,862		)	(919,521		)	1,641			599,909			922,301			94,468
Net cash (used for) provided by operating activities	(13,876		)	(300,529		)	485,146			605,383			—			776,124
Cash flows from investing activities
Acquisition of business	—			—			—			(611,087		)	—			(611,087		)
Additions to property, plant and equipment	—			(160,147		)	(144,348		)	(6,688		)	—			(311,183		)
Proceeds from disposition of assets	—			144			—			1			—			145
Proceeds from repayment of loan acquired	—			—			—			45,923			—			45,923
Proceeds from sales and maturities of securities	342,045			—			—			—			—			342,045
Purchase of securities	(117,332		)	—			—			—			—			(117,332		)
Settlements of derivative instruments	—			(556		)	(133		)	—			—			(689		)
Net cash provided by (used for) investing activities	224,713			(160,559		)	(144,481		)	(571,851		)	—			(652,178		)
Cash flows from financing activities
Intercompany financing	75,104			(143,325		)	62,221			6,000			—			—
Net distributions prior to Westlake Partners initial public offering	—			448,101			(448,101		)	—			—			—
Capitalized debt issuance costs	(1,167		)	—			—			—			—			(1,167		)
Dividends paid	(55,690		)	151,729			(151,729		)	—			—			(55,690		)
Net proceeds from issuance of Westlake Partners common units	—			—			—			286,088			—			286,088
Purchase of limited partner interests	—			—			286,088			(286,088		)	—			—
Proceeds from exercise of stock options	5,502			—			—			—			—			5,502
Repurchase of common stock for treasury	(9,495		)	—			—			—			—			(9,495		)
Windfall tax benefits from share-based payment arrangements	6,670			—			—			—			—			6,670
Net cash provided by (used for) financing activities	$	20,924		$	456,505		$	(251,521	)	$	6,000		$	—		$	231,908

29

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars, except share amounts and per share data)

	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries			OpCo (Less Than 100% Owned Guarantor Subsidiary)		Non- Guarantor Subsidiaries			Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	$	—	$	—		$	—	$	(3,687	)	$	—	$	(3,687	)
Net increase (decrease) in cash and cash equivalents	231,761		(4,583		)	89,144		35,845			—		352,167
Cash and cash equivalents at beginning of period	420,948		6,227			—		34,126			—		461,301
Cash and cash equivalents at end of period	$	652,709	$	1,644		$	89,144	$	69,971		$	—	$	813,468

30

Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations

This discussion and analysis should be read in conjunction with information contained in the accompanying unaudited consolidated interim financial statements of Westlake Chemical Corporation and the notes thereto and the consolidated financial statements and notes thereto of Westlake Chemical Corporation included in Westlake Chemical Corporation's Annual Report on Form 10-K for the fiscal year ended December 31, 2014 (the "2014 Form 10-K"). The following discussion contains forward-looking statements. Please read "Forward-Looking Statements" for a discussion of limitations inherent in such statements.

We are a vertically integrated global manufacturer and marketer of basic chemicals, vinyls, polymers and building products. Our two principal operating segments are Olefins and Vinyls. We are highly integrated along our olefins product chain with significant downstream integration into polyethylene and styrene monomer. We are also an integrated global producer of vinyls with substantial downstream integration into polyvinyl chloride ("PVC") building products.

Since 2009 and continuing through the third quarter of 2015, a cost advantage for ethane-based ethylene producers over naphtha-based ethylene producers has allowed a strong export market for polyethylene, ethylene derivatives and higher margins for North American chemical producers, including Westlake. Continued strong global demand for polyethylene has resulted in improved operating margins and cash flow for our Olefins segment in recent years. However, with the significant drop in crude oil prices beginning in the third quarter of 2014 and the resulting lower crude oil prices through the third quarter of 2015, we have seen a reduction in the cost advantage enjoyed by North American ethane-based ethylene producers. Further, crude oil price volatility in the North American and global markets has already resulted in reduced prices and margins in 2015 and may continue to do so. On the other hand, our European operations rely primarily on feedstock derived from naphtha-based ethylene crackers and may benefit from lower crude oil prices.

Continued slow recovery in the U.S. construction markets and budgetary constraints in municipal spending have contributed to lower North American demand for our vinyls products, which may continue to negatively impact our Vinyls segment operating rates and margins. Likewise, European industry production capacities currently exceed demand in the region, largely due to the weak economic environment in Europe. However, since late 2010, the PVC industry in North America has experienced an increase in PVC resin export demand, driven largely by more competitive feedstock and energy cost positions in North America. As a consequence, North American PVC resin industry operating rates have improved since 2010, largely due to higher PVC resin export shipments. In addition, the completion of our new world-scale Geismar, Louisiana chlor-alkali plant and the ethane feedstock conversion and ethylene expansion project at Westlake Chemical OpCo LP's ("OpCo") Calvert City, Kentucky ethylene plant in the fourth quarter of 2013 and in the second quarter of 2014, respectively, as well as the acquisition of Vinnolit, an integrated global leader in specialty PVC resins, in July 2014, have contributed to improved operating margins and cash flow for our Vinyls segment.

The economic environment in the United States and globally appears to be slowly improving. However, depending on the performance of the global economy in the remainder of 2015 and beyond, our financial condition, results of operations or cash flows may still be negatively impacted. In addition, the European economy has been slower to recover than the U.S. economy.

Recent Developments

On June 1, 2015, we acquired an additional 35.7% controlling interest in Suzhou Huasu Plastics Co., Ltd. ("Huasu"), a PVC joint venture based near Shanghai, People's Republic of China, from INEOS Chlor Vinyls Holdings B.V., increasing our interest in Huasu to 95.0%. Prior to the acquisition of this 35.7% interest, we owned a 59.3% interest in Huasu. Huasu has a combined annual capacity of 300 million pounds of PVC resin, 145 million pounds of PVC film and sheet and 33 million pounds of building products.

31

Results of Operations

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
	(dollars in thousands, except per share data)
Net external sales
Olefins
Polyethylene	$	423,631		$	498,450		$	1,283,545		$	1,461,097
Styrene, feedstock and other	164,466			204,647			508,507			663,851
Total Olefins	588,097			703,097			1,792,052			2,124,948
Vinyls
PVC, caustic soda and other	468,235			416,771			1,315,101			776,060
Building products	131,705			133,359			369,417			378,471
Total Vinyls	599,940			550,130			1,684,518			1,154,531
Total	$	1,188,037		$	1,253,227		$	3,476,570		$	3,279,479
Income (loss) from operations
Olefins	$	196,703		$	259,277		$	608,744		$	770,267
Vinyls	67,779			59,445			202,831			76,460
Corporate and other	(10,454		)	(11,961		)	(32,893		)	(25,123		)
Total income from operations	254,028			306,761			778,682			821,604
Interest expense	(8,211		)	(9,486		)	(26,760		)	(28,182		)
Other income (expense), net	2,636			(2,670		)	33,790			4,440
Provision for income taxes	60,033			124,449			236,824			300,231
Net income	188,420			170,156			548,888			497,631
Net income attributable to noncontrolling interests	4,816			2,399			13,847			2,399
Net income attributable to    Westlake Chemical Corporation	$	183,604		$	167,757		$	535,041		$	495,232
Diluted earnings per share	$	1.39		$	1.25		$	4.02		$	3.69
	Three Months Ended September 30, 2015						Nine Months Ended September 30, 2015
	Average Sales Price			Volume			Average Sales Price			Volume
Product sales price and volume percentage change    from prior-year period
Olefins	-31.3		%	+14.9		%	-29.2		%	+13.5		%
Vinyls	-19.8		%	+28.9		%	-25.4		%	+71.3		%
Company average	-26.3		%	+21.0		%	-27.9		%	+33.9		%
	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Average industry prices (1)
Ethane (cents/lb)	6.4			7.9			6.3			9.7
Propane (cents/lb)	9.6			24.6			11.0			26.9
Ethylene (cents/lb) (2)	28.2			66.6			33.6			59.1
Polyethylene (cents/lb) (3)	75.3			89.0			76.8			87.9
Styrene (cents/lb) (4)	64.2			85.8			61.4			85.0
Caustic soda ($/short ton) (5)	563.3			588.3			576.1			587.5
Chlorine ($/short ton) (6)	275.0			232.5			260.8			233.9
PVC (cents/lb) (7)	66.5			70.2			66.5			68.7

32

_____________

(1) Industry pricing data was obtained from IHS Chemical. We have not independently verified the data.

(2) Represents average North American spot prices of ethylene over the period as reported by IHS Chemical.

(3) Represents average North American contract prices of polyethylene low density GP-Film grade over the period as reported by IHS Chemical. Effective January 1, 2015, IHS Chemical made a non-market downward adjustment of 21 cents per pound to polyethylene low density GP-Film grade prices. For comparability, we adjusted each prior-year period's polyethylene low density GP-Film grade price downward by 21 cents per pound consistent with the IHS Chemical non-market adjustment.

(4) Represents average North American contract prices of styrene over the period as reported by IHS Chemical.

(5) Represents average North American undiscounted contract prices of caustic soda over the period as reported by IHS Chemical.

(6) Represents average North American contract prices of chlorine (into chemicals) over the period as reported by IHS Chemical.

(7) Represents average North American contract prices of PVC over the period as reported by IHS Chemical.

Summary

For the quarter ended September 30, 2015, net income attributable to Westlake Chemical Corporation was $183.6 million, or $1.39 per diluted share, on net sales of $1.2 billion. This represents an increase in net income attributable to Westlake Chemical Corporation of $15.8 million, or $0.14 per diluted share, compared to the quarter ended September 30, 2014 net income attributable to Westlake Chemical Corporation of $167.8 million, or $1.25 per diluted share, on net sales of $1.3 billion. Net income for the third quarter of 2015 was impacted by a lower effective tax rate and several plant outages as a result of maintenance turnaround activity. The lower effective tax rate was primarily due to several discrete tax items and return to provision and other adjustments which lowered the third quarter 2015 effective tax rate to 24.2%. We estimate the 2015 annual effective tax rate on ordinary income will be approximately 33.5%. Net sales for the third quarter of 2015decreased by $65.2 million compared to net sales for the third quarter of 2014, mainly due to lower sales prices for all our major products, partially offset by higher sales volumes for most of our major products and sales contributed by our specialty PVC resin business, Vinnolit, which we acquired on July 31, 2014. Income from operations was $254.0 million for the third quarter of 2015 as compared to $306.8 million for the third quarter of 2014. The decrease in income from operations for the third quarter of 2015 was mainly attributable to lower integrated product margins primarily as a result of lower sales prices in the third quarter of 2015, as compared to the prior-year period, and the lost sales, lower production rates, unabsorbed fixed manufacturing costs and other costs related to several maintenance turnarounds completed during the third quarter of 2015, partially offset by lower feedstock and energy costs, higher production rates at our Geismar chlor-alkali plant and the contribution from Vinnolit as compared to the third quarter of 2014.

For the nine months ended September 30, 2015, net income attributable to Westlake Chemical Corporation was $535.0 million, or $4.02 per diluted share, on net sales of $3.5 billion. This represents an increase in net income attributable to Westlake Chemical Corporation of $39.8 million, or $0.33 per diluted share, from the nine months ended September 30, 2014 net income attributable to Westlake Chemical Corporation of $495.2 million, or $3.69 per diluted share, on net sales of $3.3 billion. Net income for the nine months ended September 30, 2015 included: (1) a lower effective tax rate primarily due to several discrete tax items and return to provision and other adjustments; (2) plant outages as a result of maintenance turnaround activity; and (3) a net pre-tax gain of $16.0 million, or $0.13 per diluted share, related to the bargain purchase gain from the acquisition of a controlling interest in Huasu, net of related expenses, and the impairment of an equity method investment. The bargain purchase gain on acquisition was non-taxable and, in combination with the benefit from the discrete tax items and return to provision and other adjustments during the period, lowered our effective tax rate for the nine months ended September 30, 2015 to 30.1%. Net sales for the nine months ended September 30, 2015increased by $197.1 million compared to the prior-year period, primarily due to sales contributed by Vinnolit and higher sales volumes for most of our major products, partially offset by lower sales prices for all our major products. Income from operations was $778.7 million for the nine months ended September 30, 2015 as compared to $821.6 million for the nine months ended September 30, 2014, a decrease mainly attributable to lower olefins integrated product margins, primarily caused by lower sales prices, as compared to the prior-year period, and costs related to several maintenance turnarounds, partially offset by increased production at our Calvert City facilities following the completion of OpCo's feedstock conversion and ethylene expansion project, higher production rates at our Geismar chlor-alkali plant, lower feedstock and energy costs and the contribution from Vinnolit, as compared to the prior-year period. Sales prices in the first nine months of 2015 were negatively impacted by the significant decline in crude oil prices.

33

RESULTS OF OPERATIONS

Third Quarter 2015 Compared with Third Quarter 2014

Net Sales. Net sales decreased by $65.2 million, or 5.2%, to $1.2 billion in the third quarter of 2015 from $1.3 billion in the third quarter of 2014, primarily attributable to lower sales prices for all our major products, partially offset by higher sales volumes for most of our major products and sales contributed by Vinnolit and Huasu. Average sales prices for the third quarter of 2015 decreased by 26.3% as compared to the third quarter of 2014. Sales prices in the third quarter of 2015 were negatively impacted by the lower crude oil prices as compared to the prior-year period. Overall sales volumes increased by 21.0% as compared to the third quarter of 2014.

Gross Profit. Gross profit margin percentage decreased to 26.2% for the third quarter of 2015 from 28.8% for the third quarter of 2014. The third quarter 2015 gross profit benefited from lower average feedstock and energy costs. However, this increase was more than offset by lower sales prices for our major products as sales prices decreased an average of 26.3% for the third quarter of 2015 as compared to the third quarter of 2014. In addition, third quarter 2015 gross profit was negatively impacted by the lost sales, lower production rates, unabsorbed fixed manufacturing costs and other costs associated with several maintenance turnarounds at our facilities.

Selling, General and Administrative Expenses. Selling, general and administrative expenses for the third quarter of 2015 of $57.2 millionincreased by $2.4 million as compared to the third quarter of 2014, mainly due to the general and administrative costs incurred by Huasu for the third quarter of 2015 and an increase in payroll and related labor costs, including incentive compensation, partially offset by a decrease in consulting and professional fees, as compared to the prior-year period.

Interest Expense. Interest expense decreased by $1.3 million to $8.2 million in the third quarter of 2015 from $9.5 million in the third quarter of 2014 largely as a result of increased capitalized interest on major capital projects as compared to the prior-year period. Debt balances remained relatively unchanged from the prior-year period.

Other Income (Expense), Net. Other income (expense), net was net income of $2.6 million in the third quarter of 2015 compared to net expense of $2.7 million in the third quarter of 2014, mainly due to lower losses on foreign exchange, partially offset by lower income from our equity method investments.

Income Taxes. The effective income tax rate was 24.2% for the third quarter of 2015. The effective income tax rate for the third quarter of 2015 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, the foreign earnings rate differential, the increased benefit in certain prior years' deductions due to a change in the calculation methodology of the domestic manufacturing deduction and adjustments related to prior years' tax returns as filed, partially offset by state income taxes. The effective income tax rate was 42.2% for the third quarter of 2014. The effective income tax rate for the third quarter of 2014 was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.

Olefins Segment

Net Sales. Net sales decreased by $115.0 million, or 16.4%, to $588.1 million in the third quarter of 2015 from $703.1 million in the third quarter of 2014, primarily due to lower sales prices for our major products, partially offset by higher sales volumes for most of our major products, as compared to the prior-year period. Average sales prices for the Olefins segment decreased by 31.3% in the third quarter of 2015 as compared to the third quarter of 2014. Average sales volumes for the Olefins segment increased by 14.9% in the third quarter of 2015 as compared to the third quarter of 2014.

Income from Operations. Income from operations decreased by $62.6 million, or 24.1%, to $196.7 million in the third quarter of 2015 from $259.3 million in the third quarter of 2014. This decrease was mainly attributable to lower olefins integrated product margins primarily as a result of lower sales prices, partially offset by higher sales volumes for most of our major products and lower feedstock and energy costs as compared to the prior-year period. Trading activity in the third quarter of 2015 resulted in a loss of $9.3 million as compared to a loss of $6.9 million in the third quarter of 2014.

Vinyls Segment

Net Sales. Net sales increased by $49.8 million, or 9.1%, to $599.9 million in the third quarter of 2015 from $550.1 million in the third quarter of 2014. This increase was mainly attributable to sales contributed by Vinnolit and Huasu, as compared to the prior-year period, and higher sales volumes for caustic soda and PVC resin, partially offset by lower sales prices for our major products. Average sales prices for the Vinyls segment decreased by 19.8% in the third quarter of 2015 as compared to the third quarter of 2014. Average sales volumes for the Vinyls segment increased by 28.9% in the third quarter of

34

2015 as compared to the third quarter of 2014, primarily attributable to sales contributed by Vinnolit and Huasu, as compared to the prior-year period.

Income (Loss) from Operations. Income from operations increased by $8.4 million to $67.8 million in the third quarter of 2015 from $59.4 million in the third quarter of 2014, mainly attributable to higher caustic soda sales volume, primarily as a result of higher production rates at our Geismar chlor-alkali plant, and the contribution from Vinnolit, as compared to the prior-year period. The increase in third quarter 2015 income from operations was partially offset by the lost sales, lower production rates, unabsorbed fixed manufacturing costs and other costs associated with the maintenance turnarounds at our Calvert City, Gendorf, Germany and Burghausen, Germany facilities and lower sales prices for our major products, as compared to the third quarter of 2014. Third quarter 2014 income from operations was negatively impacted by the lost sales, lower production rates and other costs associated with the unplanned outages at our Calvert City and Geismar facilities and the effect of selling higher cost Vinnolit inventory recorded at fair value as a result of the acquisition.

Nine Months Ended September 30, 2015 Compared with Nine Months Ended September 30, 2014

Net Sales. Net sales increased by $197.1 million, or 6.0%, to $3.5 billion for the nine months ended September 30, 2015 from $3.3 billion for the nine months ended September 30, 2014, primarily attributable to sales contributed by Vinnolit and Huasu, as compared to the prior-year period, and higher sales volumes for most of our major products, partially offset by lower sales prices for all our major products. Average sales prices for the nine months ended September 30, 2015 decreased by 27.9% as compared to the nine months ended September 30, 2014. Sales prices in the first nine months of 2015 were negatively impacted by the significant decline in crude oil prices. Overall sales volumes for the nine months ended September 30, 2015 increased by 33.9% as compared to the nine months ended September 30, 2014.

Gross Profit. Gross profit margin percentage of 27.3% for the nine months ended September 30, 2015decreased from the 29.1% gross profit margin percentage for the nine months ended September 30, 2014. The decrease was mainly the result of lower olefins integrated product margins primarily due to lower sales prices. Sales prices decreased an average of 27.9% for the nine months ended September 30, 2015 as compared to the prior-year period. In addition, gross profit for the nine months ended September 30, 2015 was negatively impacted by lost sales, lower production rates, unabsorbed fixed manufacturing costs and other costs associated with maintenance turnarounds at our various facilities. The decrease in gross profit for the nine months ended September 30, 2015 was partially offset by lower average feedstock and energy costs and higher vinyls integrated product margins, primarily attributable to lower feedstock costs, increased production at our Calvert City facilities following the completion of OpCo's feedstock conversion and ethylene expansion project and higher production rates at our Geismar chlor-alkali plant, as compared to the prior-year period.

Selling, General and Administrative Expenses. Selling, general and administrative expenses for the nine months ended September 30, 2015increased by $37.4 million as compared to the nine months ended September 30, 2014, mainly attributable to general and administrative costs incurred by Vinnolit and Huasu for the nine months ended September 30, 2015, an increase in payroll and related labor costs, including incentive compensation, and an increase in consulting and professional fees, as compared to the prior-year period.

Interest Expense. Interest expense decreased by $1.4 million to $26.8 million for the nine months ended September 30, 2015, largely as a result of increased capitalized interest on major capital projects as compared to the prior-year period. Debt balances remained relatively unchanged from the prior-year period.

Other Income, Net. Other income, net increased by $29.4 million to $33.8 million for the nine months ended September 30, 2015 from $4.4 million for the nine months ended September 30, 2014. The increase from the prior-year period was principally due to the bargain purchase gain from the acquisition of a controlling interest in Huasu, net of related expenses, of approximately $20.4 million, gains on foreign exchange, the gain from the sales of equity securities and dividends received from cost method investments, partially offset by the impairment and loss from the disposition of an equity method investment.

Income Taxes. The effective income tax rate was 30.1% for the nine months ended September 30, 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, the non-recognition of tax related to the bargain purchase of a controlling interest in Huasu, the increased benefit in certain prior years' deductions due to a change in the calculation methodology of the domestic manufacturing deduction and adjustments related to prior years' tax returns as filed and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 37.6% for the nine months ended September 30, 2014. The effective income tax rate for the 2014 period was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.

35

Olefins Segment

Net Sales. Net sales decreased by $332.8 million, or 15.7%, to $1.8 billion for the nine months ended September 30, 2015 from $2.1 billion for the nine months ended September 30, 2014, mainly due to lower sales prices for our major products, partially offset by higher sales volumes for our major products as compared to the prior-year period. Average sales prices for the Olefins segment decreased by 29.2% for the nine months ended September 30, 2015 as compared to the nine months ended September 30, 2014. Average sales volumes for the Olefins segment increased by 13.5% for the nine months ended September 30, 2015 as compared to the nine months ended September 30, 2014.

Income from Operations. Income from operations decreased by $161.6 million, or 21.0%, to $608.7 million for the nine months ended September 30, 2015 from $770.3 million for the nine months ended September 30, 2014. This decrease was mainly attributable to lower olefins integrated product margins, primarily as a result of lower sales prices, partially offset by higher sales volumes and lower feedstock and energy costs for the nine months ended September 30, 2015 as compared to the prior-year period.

Vinyls Segment

Net Sales. Net sales increased by $530.0 million, or 45.9%, to $1.7 billion for the nine months ended September 30, 2015 from $1.2 billion for the nine months ended September 30, 2014. This increase was primarily attributable to sales contributed by Vinnolit and Huasu and higher sales volumes for caustic soda and PVC resin, partially offset by lower sales prices for our major products. Average sales prices for the Vinyls segment decreased by 25.4% for the nine months ended September 30, 2015 as compared to the nine months ended September 30, 2014. Average sales volumes for the Vinyls segment increased by 71.3% for the nine months ended September 30, 2015 as compared to the nine months ended September 30, 2014, primarily related to sales contributed by Vinnolit and Huasu, as compared to the prior-year period.

Income from Operations. Income from operations increased by $126.3 million to $202.8 million for the nine months ended September 30, 2015 from $76.5 million for the nine months ended September 30, 2014. This increase was primarily driven by higher vinyls integrated product margins for the nine months ended September 30, 2015, mainly attributable to lower feedstock costs and increased production at our Calvert City facilities following the completion of OpCo's feedstock conversion and ethylene expansion project, higher caustic soda sales volume primarily attributable to higher production rates at our Geismar chlor-alkali plant and the contribution from Vinnolit, as compared to the prior-year period. The increase in income from operations for the nine months ended September 30, 2015 was partially offset by lost sales, lower production rates and other costs associated with the maintenance turnarounds at our various North American and European facilities, lower sales prices for our major products and reduced sales volume in Europe related to an ethylene shortage. Income from operations for the nine months ended September 30, 2014 was negatively impacted by the effect of selling higher cost Vinnolit inventory recorded at fair value as a result of the acquisition, the lost sales, lower production rates and other costs associated with the maintenance turnaround at our Calvert City facilities and OpCo's Calvert City ethylene plant's feedstock conversion and expansion project and, prior to the completion of OpCo's Calvert City ethylene plant's feedstock conversion project, lower vinyls integrated product margins attributable to significantly higher propane costs.

CASH FLOW DISCUSSION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2015 AND 2014

Cash Flows

Operating Activities

Operating activities provided cash of $841.3 million in the first nine months of 2015 compared to cash provided of $776.1 million in the first nine months of 2014. The $65.2 millionincrease in cash flows from operating activities was mainly due to an increase in net income and a decrease in working capital requirements, as compared to the prior-year period. Cash flows from operating activities for the first nine months of 2014 were negatively impacted by costs related to the formation and initial public offering of Westlake Chemical Partners LP ("Westlake Partners") and costs associated with the acquisition of Vinnolit, our specialty PVC resin business, including the effect of selling higher cost inventory recorded at fair value. Changes in components of working capital, which we define for purposes of this cash flow discussion as accounts receivable, net, inventories, prepaid expenses and other current assets, less accounts payable and accrued liabilities, provided cash of $113.9 million in the first nine months of 2015, compared to $100.3 million of cash provided in the first nine months of 2014, a favorable change of $13.6 million. The change was mainly due to lower accounts receivable and inventory balances mainly as a result of lower product prices during the 2015 period, partially offset by a decrease in current liabilities (accounts payable and accrued liabilities), as compared to the prior-year period.

36

Investing Activities

Net cash used for investing activities during the first nine months of 2015 was $553.6 million as compared to net cash used for investing activities of $652.2 million in the first nine months of 2014. Capital expenditures were $329.2 million in the first nine months of 2015 compared to $311.2 million in the first nine months of 2014. Capital expenditures in the first nine months of 2015 were primarily incurred on the planned upgrade and expansion of OpCo's Petro 1 ethylene unit at our Lake Charles, Louisiana site. Capital expenditures in the first nine months of 2014 were mainly incurred on OpCo's feedstock conversion and ethylene expansion project and our PVC plant expansion project at our Calvert City site and the planned upgrade and expansion of OpCo's Petro 1 ethylene unit at our Lake Charles site. The remaining capital expenditures in the first nine months of 2015 and 2014 primarily related to projects to improve production capacity or reduce costs, maintenance and safety projects and environmental projects at our various facilities. We acquired cash of $15.8 million, net of cash paid, in connection with the acquisition of Huasu. Purchases of securities in the first nine months of 2015 totaled $282.5 million and were comprised of corporate and U.S. government debt securities. We also received aggregate proceeds of $16.1 million from the sales and maturities of our investments in the first nine months of 2015. The activity during the first nine months of 2014 was primarily related to the acquisition of Vinnolit, the purchase of securities and the receipt of proceeds from the sales and maturities of our investments.

Financing Activities

Net cash used by financing activities during the first nine months of 2015 was $203.1 million as compared to net cash provided of $231.9 million in the first nine months of 2014. The activity during the first nine months of 2015 was primarily related to the $67.9 million payment of cash dividends, the $11.0 million payment of cash distributions to noncontrolling interests and the $114.3 million of cash used for repurchases of shares of our common stock, partially offset by the receipt of proceeds of $1.0 million from the exercise of stock options. In addition, we repaid $33.0 million of our joint venture's short-term notes payable to banks, partially offset by $19.5 million of proceeds received by our joint venture from the issuance of the notes payable. The activity during the first nine months of 2014 was mainly related to the $286.1 million net proceeds from the initial public offering of Westlake Partners common units and the proceeds from the exercise of stock options, partially offset by the payment of cash dividends and the repurchase of shares of our common stock.

LIQUIDITY AND CAPITAL RESOURCES

Liquidity and Financing Arrangements

Our principal sources of liquidity are from cash and cash equivalents, investments in current marketable securities, cash from operations, short-term borrowings under our revolving credit facility and our long-term financing.

In April 2011, we announced an expansion program to increase the ethane-based ethylene capacity of both of OpCo's ethylene units at our Lake Charles site. We completed the expansion of the Petro 2 ethylene unit in the first quarter of 2013. OpCo currently plans to begin the upgrade and capacity expansion of its Petro 1 ethylene unit at our Lake Charles site in the second quarter of 2016. This project is currently estimated to cost in the range of $275.0 million to $335.0 million and is expected to add approximately 250 million pounds of ethylene capacity. The additional capacity from this expansion is expected to provide ethylene for sales to us and may also be sold in the merchant market. This capital project is expected to be funded with cash on hand, cash flow from operations, and, if necessary, borrowings under each of our revolving credit facility and OpCo's revolving credit facility with another subsidiary of ours and other financing. As of September 30, 2015, OpCo had incurred a total cost of approximately $150.8 million on this capital project.

In August 2011, our Board of Directors authorized a stock repurchase program totaling $100.0 million (the "2011 Program"). As of March 31, 2015, we had repurchased the full amount of the 2011 Program. In November 2014, our Board of Directors approved an additional $250.0 million share repurchase program (the "2014 Program"). During the three months ended September 30, 2015, we repurchased 1,090,837 shares of our common stock for an aggregate purchase price of approximately $59.4 million under the 2014 Program. As of September 30, 2015, we had repurchased 1,955,871 shares of our common stock for an aggregate purchase price of approximately $121.1 million under the 2014 Program. Purchases under the 2014 Program may be made either through the open market or in privately negotiated transactions. Decisions regarding the amount and the timing of purchases under the 2014 Program will be influenced by our cash on hand, our cash flow from operations, general market conditions and other factors. The 2014 Program may be discontinued by our Board of Directors at any time.

We believe that our sources of liquidity as described above will be adequate to fund our normal operations and ongoing capital expenditures. Funding of any potential large expansions or any potential acquisitions would likely necessitate and therefore depend on our ability to obtain additional financing in the future. We may not be able to access additional liquidity at cost effective interest rates due to the volatility of the commercial credit markets. Our management believes that borrowing

37

under our revolving credit facility should be available up to our borrowing base, if needed. At September 30, 2015, the borrowing base of our credit facility was $376.3 million, which is below the maximum borrowing capacity of $400.0 million due to our low carrying amount of accounts receivable and inventory, which make up the borrowing base.

Cash and Cash Equivalents

As of September 30, 2015, our cash, cash equivalents and current marketable securities totaled $1.2 billion. In addition, we have a revolving credit facility available to supplement cash if needed, as described under "Debt" below.

Debt

As of September 30, 2015, our long-term debt, including current maturities, totaled $764.1 million, consisting of $250.0 million principal amount of 3.60% senior notes due 2022 (less the unamortized discount of $0.8 million), $100.0 million of 6 ½% senior notes due 2029, $250.0 million of 6 ¾% senior notes due 2032, $89.0 million of 6 ½% senior notes due 2035 (the "6 ½% GO Zone Senior Notes Due 2035"), $65.0 million of 6 ½% senior notes due 2035 (the "6 ½% IKE Zone Senior Notes Due 2035") (collectively, but excluding the 3.60% senior notes due 2022, the "Senior Notes") and a $10.9 million loan from the proceeds of tax-exempt waste disposal revenue bonds (supported by an $11.3 million letter of credit). The 6 ½% senior notes due 2029, the 6 ¾% senior notes due 2032, the 6 ½% GO Zone Senior Notes Due 2035 and the 6 ½% IKE Zone Senior Notes Due 2035 evidence and secure our obligations to the Louisiana Local Government Environmental Facility and Development Authority (the "Authority"), a political subdivision of the State of Louisiana, under four loan agreements relating to the issuance of $100.0 million, $250.0 million, $89.0 million and $65.0 million aggregate principal amount of the Authority's tax-exempt revenue bonds, respectively. As of September 30, 2015, debt outstanding under the tax-exempt waste disposal revenue bonds bore interest at a variable rate. As of September 30, 2015, we were in compliance with all of the covenants with respect to the 3.60% senior notes due 2022, the Senior Notes, our waste disposal revenue bonds and our revolving credit facility.

Our ability to make payments on our indebtedness and to fund planned capital expenditures will depend on our ability to generate cash in the future, which is subject to general economic, financial, competitive, legislative, regulatory and other factors that are beyond our control. Based on our current level of operations and unless we were to undertake a new expansion or large acquisition, we believe our cash flow from operations, available cash and available borrowings under our revolving credit facility will be adequate to meet our normal operating needs for the foreseeable future.

Revolving Credit Facility

We have a $400.0 million senior secured revolving credit facility. The facility includes a provision permitting us to increase the size of the facility, up to four times, in increments of at least $25.0 million each (up to a maximum of $200.0 million) under certain circumstances if certain lenders agree to commit to such an increase.

At September 30, 2015, we 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 we are rated investment grade, the margin for LIBOR loans will not exceed 1.50%, or a base rate plus a spread ranging from 0.0% 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 September 30, 2015, we had outstanding letters of credit totaling $30.0 million and borrowing availability of $346.4 million under the revolving credit facility.

Our revolving credit facility generally restricts our ability to make distributions unless, on a pro forma basis after giving effect to the distribution, the borrowing availability under the facility equals or exceeds the greater of (1) 20% of the commitments under the facility and (2) $80.0 million; or the borrowing availability under the facility equals or exceeds the greater of (1) 15% of the commitments under the facility and (2) $60.0 million, and our fixed charge coverage ratio is at least 1.0:1. However, we may make specified distributions up to an aggregate of $78.8 million in 2015, to be increased by 5% in each fiscal year thereafter, on an aggregate basis, for each fiscal year.

In order to make acquisitions or investments, our revolving credit facility provides that (1) we must maintain a minimum borrowing availability of at least the greater of $60.0 million or 15% of the total bank commitments under our revolving credit facility or (2) we must maintain a minimum borrowing availability of at least the greater of $50.0 million or 12.5% of the total bank commitments under our revolving credit facility and meet a minimum fixed charge coverage ratio of 1.0:1 under our revolving credit facility. Notwithstanding the foregoing, we may make investments in the aggregate up to the greater of $50.0 million and 1.25% of tangible assets and acquisitions in the aggregate up to the greater of $100.0 million and 2.5% of tangible assets, if, on a pro forma basis after giving effect to the acquisition or investment, either (X) the borrowing availability under the facility equals or exceeds the greater of (A) 12.5% of the total bank commitments under the facility and (B) $50.0 million,

38

but is less than the greater of (A) 15% of the total bank commitments and (B) $60.0 million, or (Y) our fixed charge coverage ratio is at least 1.0:1.

The revolving credit facility contains other customary covenants and events of default that impose significant operating and financial restrictions on us. These restrictions, among other things, provide limitations on the occurrence of additional indebtedness and our ability to create liens, to engage in certain affiliate transactions and to engage in sale-leaseback transactions. See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Debt" in the 2014 Form 10-K for more information on the revolving credit facility.

GO Zone and IKE Zone Bonds

As of September 30, 2015, we had drawn all the proceeds from the issuance of the 6 ½% senior notes due 2029, 6 ¾% senior notes due 2032, 6 ½% GO Zone Senior Notes Due 2035 and 6 ½% IKE Zone Senior Notes Due 2035. See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Debt" in the 2014 Form 10-K for more information on the 6 ½% senior notes due 2029, the 6 ¾% senior notes due 2032, the 6 ½% GO Zone Senior Notes Due 2035 and the 6 ½% IKE Zone Senior Notes Due 2035. All domestic restricted subsidiaries that guarantee other debt of ours or of another guarantor of the Senior Notes in excess of $5.0 million are guarantors of these notes.

The indentures governing the Senior Notes contain customary covenants and events of default. Accordingly, these agreements generally impose significant operating and financial restrictions on us. These restrictions, among other things, provide limitations on incurrence of additional indebtedness, the payment of dividends, certain investments and acquisitions and sales of assets. However, the effectiveness of certain of these restrictions is currently suspended because the Senior Notes are currently rated investment grade by at least two nationally recognized credit rating agencies. The most significant of these provisions, if it were currently effective, would restrict us from incurring additional debt, except specified permitted debt (including borrowings under our credit facility), when our fixed charge coverage ratio is below 2.0:1. These limitations are subject to a number of important qualifications and exceptions, including, without limitation, an exception for the payment of our regular quarterly dividend of up to $0.10 per share. If the restrictions were currently effective, distributions in excess of $100.0 million would not be allowed unless, after giving pro forma effect to the distribution, our fixed charge coverage ratio is at least 2.0:1 and such payment, together with the aggregate amount of all other distributions after January 13, 2006, is less than the sum of 50% of our consolidated net income for the period from October 1, 2003 to the end of the most recent quarter for which financial statements have been filed, plus 100% of net cash proceeds received after October 1, 2003 as a contribution to our common equity capital or from the issuance or sale of certain securities, plus several other adjustments.

3.60% Senior Notes due 2022

The 3.60% senior notes due 2022 are unsecured and were issued with an original issue discount of $1.2 million. There is no sinking fund and no scheduled amortization of the 3.60% senior notes due 2022 prior to maturity. See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Debt" in the 2014 Form 10-K for more information on the 3.60% senior notes due 2022. All of our domestic subsidiaries that guarantee other indebtedness of ours or of another guarantor of the 3.60% senior notes due 2022 in excess of $5.0 million are guarantors of the 3.60% senior notes due 2022.

The indenture governing the 3.60% senior notes due 2022 contains customary events of default and covenants that will restrict our and certain of our subsidiaries' ability to (1) incur certain secured indebtedness, (2) engage in certain sale-leaseback transactions and (3) consolidate, merge or transfer all or substantially all of our assets.

Revenue Bonds

In December 1997, we entered into a loan agreement with a public trust established for public purposes for the benefit of the Parish of Calcasieu, Louisiana. The public trust issued $10.9 million principal amount of tax-exempt waste disposal revenue bonds in order to finance our construction of waste disposal facilities for an ethylene plant. The waste disposal revenue bonds expire in December 2027 and are subject to redemption and mandatory tender for purchase prior to maturity under certain conditions. Interest on the waste disposal revenue bonds accrues at a rate determined by a remarketing agent and is payable quarterly.

Westlake Partners Credit Arrangements

Our subsidiary, Westlake Chemical Finance Corporation, is the lender party to a $300.0 million revolving credit facility with Westlake Partners, entered into on April 29, 2015. The revolving credit facility matures on April 29, 2018. Borrowings under the revolver bear interest at LIBOR plus a spread ranging from 2.0% to 3.0% (depending on Westlake Partners'

39

consolidated leverage ratio), payable quarterly. Westlake Partners may pay all or a portion of the interest on any borrowings in kind, in which case any such amounts would be added to the principal amount of the loan. As of September 30, 2015, outstanding borrowings under the credit facility totaled $135.3 million and bore interest at the LIBOR rate plus 2.0%.

Our subsidiary, Westlake Development Corporation, is the lender party to a $600.0 million revolving credit facility with OpCo. The revolving credit facility matures in 2019. As of September 30, 2015, outstanding borrowings under the credit facility totaled $163.4 million and bore interest at the LIBOR rate plus 3.0%, which is accrued in arrears quarterly.

We consolidate Westlake Partners and OpCo for financial reporting purposes as we have a controlling financial interest. As such, the revolving credit facilities described above between our subsidiaries and Westlake Partners and OpCo are eliminated upon consolidation.

Off-Balance Sheet Arrangements

None.

FORWARD-LOOKING STATEMENTS

The Private Securities Litigation Reform Act of 1995 provides safe harbor provisions for forward-looking information. Certain of the statements contained in this report are forward-looking statements. All statements, other than statements of historical facts, included in this report that address activities, events or developments that we expect, project, believe or anticipate will or may occur in the future are forward-looking statements. Forward-looking statements can be identified by the use of words such as "believes," "intends," "may," "should," "could," "anticipates," "expected" or comparable terminology, or by discussions of strategies or trends. Although we believe that the expectations reflected in such forward-looking statements are reasonable, we cannot give any assurances that these expectations will prove to be correct. Forward-looking statements relate to matters such as:

• future operating rates, margins, cash flow and demand for our products;

• industry market outlook, including the price of crude oil;

• production capacities;

• currency devaluation;

• our ability to borrow additional funds under our credit facility;

• availability of our revolving credit facility and our ability to meet our liquidity needs;

• our intended quarterly dividends;

• our effective tax rate;

• future capacity additions and expansions in the industry;

• timing, funding and results of capital projects, such as the expansion program at our Lake Charles facility;

• results of acquisitions;

• pension plan obligations, funding requirements and investment policies;

• compliance with present and future environmental regulations and costs associated with environmentally related penalties, capital expenditures, remedial actions and proceedings, including any new laws, regulations or treaties that may come into force to limit or control carbon dioxide and other greenhouse gases emissions or to address other issues of climate change;

• effects of pending legal proceedings; and

• timing of and amount of capital expenditures.

We have based these statements on assumptions and analyses in light of our experience and perception of historical trends, current conditions, expected future developments and other factors we believe were appropriate in the circumstances when the statements were made. Forward-looking statements by their nature involve substantial risks and uncertainties that could significantly impact expected results, and actual future results could differ materially from those described in such statements. These statements are subject to a number of assumptions, risks and uncertainties, including those described in "Risk Factors" in the 2014 Form 10-K and the following:

• general economic and business conditions;

• the cyclical nature of the chemical industry;

40

• the availability, cost and volatility of raw materials and energy;

• uncertainties associated with the United States, European and worldwide economies, including those due to political tensions and unrest in the Middle East, the Commonwealth of Independent States (including Ukraine) and elsewhere;

• current and potential governmental regulatory actions in the United States and Europe and regulatory actions and political unrest in other countries;

• industry production capacity and operating rates;

• the supply/demand balance for our products;

• competitive products and pricing pressures;

• instability in the credit and financial markets;

• access to capital markets;

• terrorist acts;

• operating interruptions (including leaks, explosions, fires, weather-related incidents, mechanical failure, unscheduled downtime, labor difficulties, transportation interruptions, spills and releases and other environmental risks);

• changes in laws or regulations;

• technological developments;

• our ability to integrate acquired businesses;

• foreign currency exchange risks;

• our ability to implement our business strategies; and

• creditworthiness of our customers.

Many of these factors are beyond our ability to control or predict. Any of the factors, or a combination of these factors, could materially affect our future results of operations and the ultimate accuracy of the forward-looking statements. These forward-looking statements are not guarantees of our future performance, and our actual results and future developments may differ materially from those projected in the forward-looking statements. Management cautions against putting undue reliance on forward-looking statements or projecting any future results based on such statements or present or prior earnings levels. Every forward-looking statement speaks only as of the date of the particular statement, and we undertake no obligation to publicly update or revise any forward-looking statements.

Item 3. Quantitative and Qualitative Disclosures about Market Risk

Commodity Price Risk

A substantial portion of our products and raw materials are commodities whose prices fluctuate as market supply and demand fundamentals change. Accordingly, product margins and the level of our profitability tend to fluctuate with changes in the business cycle. We try to protect against such instability through various business strategies. Our strategies include ethylene feedstock flexibility and moving downstream into the olefins and vinyls products where pricing is more stable. We use derivative instruments in certain instances to reduce price volatility risk on feedstocks and products. Based on our open derivative positions at September 30, 2015, a hypothetical $0.10 increase in the price of a gallon of ethane would have increased our income before taxes by $18.7 million and a hypothetical $0.10 increase in the price of a MMbtu of natural gas would have increased our income before taxes by $1.3 million. Additional information concerning derivative commodity instruments appears in Notes 12 and 13 to the unaudited consolidated financial statements within this Quarterly Report on Form 10-Q.

Interest Rate Risk

We are exposed to interest rate risk with respect to fixed and variable rate debt. At September 30, 2015, we had variable rate debt of $10.9 million outstanding. All of the debt outstanding under our revolving credit facility (none was outstanding at September 30, 2015) and our loan relating to the tax-exempt waste disposal revenue bonds are at variable rates. We do not currently hedge our variable interest rate debt, but we may do so in the future. The average variable interest rate for our variable rate debt of $10.9 million as of September 30, 2015 was 0.09%. A hypothetical 100 basis point increase in the average interest rate on our variable rate debt would increase our annual interest expense by approximately $0.1 million. Also, at September 30, 2015, we had $754.0 million aggregate principal amount of fixed rate debt. We are subject to the risk of higher interest cost if

41

and when this debt is refinanced. If interest rates are 1% higher at the time of refinancing, our annual interest expense would increase by approximately $7.5 million.

Foreign Currency Exchange Rate Risk

We are exposed to foreign currency exchange rate risk associated with our international operations. However, the effect of fluctuations in foreign currency exchange rates caused by our international operations has not had a material impact on our overall operating results. We may engage in activities to mitigate our exposure to foreign currency exchange risk in certain instances through the use of currency exchange derivative instruments, including forward exchange contracts, or spot purchases. A forward exchange contract obligates us to exchange predetermined amounts of specified currencies at a stated exchange rate on a stated date.

Item 4. Controls and Procedures

We carried out an evaluation, under the supervision and with the participation of our management, including our President and Chief Executive Officer and our Senior Vice President, Chief Financial Officer and Treasurer, of the effectiveness of our disclosure controls and procedures pursuant to Rules 13a-15 or 15d-15 under the Securities Exchange Act of 1934 as of the end of the period covered by this report. Based upon that evaluation, our President and Chief Executive Officer and our Senior Vice President, Chief Financial Officer and Treasurer concluded that our disclosure controls and procedures are effective with respect to (i) the accumulation and communication to our management, including our Chief Executive Officer and our Chief Financial Officer, of information required to be disclosed by us in the reports that we submit under the Exchange Act, and (ii) the recording, processing, summarizing and reporting of such information within the time periods specified in the SEC's rules and forms.

There were no changes in our internal control over financial reporting that occurred during the three months ended September 30, 2015 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

42

PART II. OTHER INFORMATION

Item 1. Legal Proceedings

The 2014 Form 10-K, filed on February 25, 2015, contained a description of various legal proceedings in which we are involved, including environmental proceedings at our facilities in Calvert City. See Note 19 to the unaudited consolidated financial statements within this Quarterly Report on Form 10-Q for a description of certain of those proceedings, which information is incorporated by reference herein.

Item 1A. Risk Factors

For a discussion of risk factors, please read Item 1A, "Risk Factors" in the 2014 Form 10-K and in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2015. There have been no material changes from those risk factors.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

The following table provides information on our purchase of equity securities during the quarter ended September 30, 2015.

Period	Total Number of Shares Purchased (1) (2)	Average Price Paid Per Share		Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs (2)	Maximum Number (or Approximate Dollar Value) of Shares that May Yet Be Purchased Under the Plans or Programs (2)
July 2015	95,082	$	68.66	95,019	$	181,822,000
August 2015	190,989	$	57.44	190,989	$	170,851,000
September 2015	804,829	$	52.12	804,829	$	128,901,000
	1,090,900	$	53.14	1,090,837

_____________

(1) Represents shares withheld in satisfaction of withholding taxes due upon the vesting of restricted stock and restricted stock units granted to our employees under the 2013 Plan.

(2) On August 22, 2011, we announced the authorization by our Board of Directors of a $100.0 million stock repurchase program (the "2011 Program"). As of March 31, 2015, we had repurchased the full amount of the 2011 Program. On November 21, 2014, our Board of Directors approved an additional $250.0 million share repurchase program (the "2014 Program"). As of September 30, 2015, 1,955,871 shares of common stock had been acquired at an aggregate purchase price of $121.1 million under the 2014 Program. Decisions regarding the amount and the timing of purchases under the 2014 Program will be influenced by our cash on hand, our cash flow from operations, general market conditions and other factors. The 2014 Program may be discontinued by our Board of Directors at any time.

43

Item 6. Exhibits

Exhibit No.
31.1†	Rule 13a – 14(a) / 15d – 14(a) Certification (Principal Executive Officer)
31.2†	Rule 13a – 14(a) / 15d – 14(a) Certification (Principal Financial Officer)
32.1#	Section 1350 Certification (Principal Executive Officer and Principal Financial Officer)
99.1#	Unaudited Financial Statements of Non Wholly-Owned Subsidiary Guarantor (Westlake Chemical OpCo LP)
101.INS†	XBRL Instance Document
101.SCH†	XBRL Taxonomy Extension Schema Document
101.CAL†	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF†	XBRL Taxonomy Extension Definition Linkbase Document
101.LAB†	XBRL Taxonomy Extension Label Linkbase Document
101.PRE†	XBRL Taxonomy Extension Presentation Linkbase Document

______________________________

† Filed herewith.

# Furnished herewith.

44

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		WESTLAKE CHEMICAL CORPORATION
Date:	November 4, 2015	By:	/S/    ALBERT CHAO
			Albert Chao
			President and Chief Executive Officer (Principal Executive Officer)
Date:	November 4, 2015	By:	/S/    M. STEVEN BENDER
			M. Steven Bender
			Senior Vice President, Chief Financial Officer and Treasurer (Principal Financial Officer)

45

EXHIBIT INDEX

Exhibit No.	Exhibit
31.1†	Rule 13a – 14(a) / 15d – 14(a) Certification (Principal Executive Officer)
31.2†	Rule 13a – 14(a) / 15d – 14(a) Certification (Principal Financial Officer)
32.1#	Section 1350 Certification (Principal Executive Officer and Principal Financial Officer)
99.1#	Unaudited Financial Statements of Non Wholly-Owned Subsidiary Guarantor (Westlake Chemical OpCo LP)
101.INS†	XBRL Instance Document
101.SCH†	XBRL Taxonomy Extension Schema Document
101.CAL†	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF†	XBRL Taxonomy Extension Definition Linkbase Document
101.LAB†	XBRL Taxonomy Extension Label Linkbase Document
101.PRE†	XBRL Taxonomy Extension Presentation Linkbase Document

______________________________

† Filed herewith.

# Furnished herewith.

46

EX-31.1

Exhibit 31.1

CERTIFICATIONS

I, Albert Chao, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Westlake Chemical Corporation;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	November 4, 2015	/S/    ALBERT CHAO
		Albert Chao
		President and Chief Executive Officer (Principal Executive Officer)

EX-31.2

Exhibit 31.2

CERTIFICATIONS

I, M. Steven Bender, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Westlake Chemical Corporation;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	November 4, 2015	/S/ M. STEVEN BENDER
		M. Steven Bender
		Senior Vice President, Chief Financial Officer and Treasurer (Principal Financial Officer)

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Westlake Chemical Corporation (the "Company") on Form 10-Q for the fiscal quarter ended September 30, 2015 as filed with the Securities and Exchange Commission on the date hereof (the "Report"), I, Albert Chao, President and Chief Executive Officer of the Company, and I, M. Steven Bender, Senior Vice President, Chief Financial Officer and Treasurer of the Company, certify, to the best of our knowledge, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that:

(1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material aspects, the financial condition and results of operations of the Company.

Date:	November 4, 2015	/S/    ALBERT CHAO
		Albert Chao
		President and Chief Executive Officer (Principal Executive Officer)
Date:	November 4, 2015	/S/    M. STEVEN BENDER
		M. Steven Bender
		Senior Vice President, Chief Financial Officer and Treasurer (Principal Financial Officer)

EX-99.1

Exhibit 99.1

Westlake Chemical OpCo LP

Combined Financial Statements for the quarterly period ended September 30, 2015

FINANCIAL STATEMENTS

WESTLAKE CHEMICAL OPCO LP

BALANCE SHEETS

(Unaudited)

	September 30, 2015		December 31, 2014
	(in thousands of dollars)
ASSETS
Current assets
Cash and cash equivalents	$	149,482	$	131,545
Accounts receivable, net—Westlake Chemical Corporation ("Westlake")	44,035		18,529
Accounts receivable, net—third parties	14,479		37,520
Inventories	3,272		6,634
Prepaid expenses and other current assets	382		212
Total current assets	211,650		194,440
Property, plant and equipment, net	962,221		842,057
Other assets, net
Goodwill	5,814		5,814
Deferred charges and other assets, net	40,728		51,919
Total other assets, net	46,542		57,733
Total assets	$	1,220,413	$	1,094,230
LIABILITIES
Current liabilities
Accounts payable—Westlake	$	8,605	$	5,332
Accounts payable—third parties	24,871		12,348
Accrued liabilities	21,055		11,225
Total current liabilities	54,531		28,905
Long-term debt payable to Westlake	195,154		227,638
Deferred income taxes	1,489		1,848
Total liabilities	251,174		258,391
Commitments and contingencies (Notes 8 and 13)
EQUITY
Limited partners interest—Westlake	500,479		504,854
Limited partner interest—Westlake Chemical Partners LP	468,760		330,985
Total equity	969,239		835,839
Total liabilities and equity	$	1,220,413	$	1,094,230

The accompanying notes are an integral part of the combined financial statements.

1

WESTLAKE CHEMICAL OPCO LP

COMBINED STATEMENTS OF OPERATIONS

(Unaudited)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
	(in thousands of dollars)
Revenue
Net sales—Westlake	$	207,856		$	289,601		$	621,438		$	1,088,561
Net co-product, ethylene and feedstock sales—third   parties	40,763			102,407			137,277			387,596
Total net sales	248,619			392,008			758,715			1,476,157
Cost of sales	154,474			227,015			473,815			832,304
Gross profit	94,145			164,993			284,900			643,853
Selling, general and administrative expenses	4,941			8,014			15,178			21,957
Income from operations	89,204			156,979			269,722			621,896
Other income (expense)
Interest expense—Westlake	(217		)	(2,137		)	(2,449		)	(9,833		)
Other (expense) income, net	(124		)	486			(85		)	3,135
Income before income taxes	88,863			155,328			267,188			615,198
Provision for income taxes	141			36,309			567			198,461
Net income	88,722			119,019			266,621			416,737
Less: Predecessor net income prior to initial public   offering on August 4, 2014	—			63,616			—			361,334
Net income subsequent to initial public offering	$	88,722		$	55,403		$	266,621		$	55,403

The accompanying notes are an integral part of the combined financial statements.

2

WESTLAKE CHEMICAL OPCO LP

COMBINED STATEMENTS OF CHANGES IN EQUITY

(Unaudited)

	Predecessor			Westlake Chemical OpCo LP
	Net Investment			Limited Partners Interest—Westlake			Limited Partner Interest— Westlake Chemical Partners LP			Total
	(in thousands of dollars)
Balances at December 31, 2013	$	455,432		$	—		$	—		$	455,432
Net income from January 1, 2014 through August 3,   2014	361,334			—			—			361,334
Net distributions to Westlake prior to initial public   offering	(448,101		)	—			—			(448,101		)
Predecessor net liabilities not assumed by OpCo	239,706			—			—			239,706
Balance as of August 4, 2014 (prior to initial public   offering)	608,371			—			—			608,371
Allocation of net investment to partners' capital	(608,371		)	573,329			35,042			—
Capital contribution from Westlake Chemical Partners   LP	—			—			286,088			286,088
Proceeds from capital contribution from Westlake   Chemical Partners LP distributed to Westlake	—			(151,729		)	—			(151,729		)
Net income from August 4, 2014 through September 30,   2014	—			49,542			5,861			55,403
Balances at September 30, 2014	$	—		$	471,142		$	326,991		$	798,133
Balances at December 31, 2014	$	—		$	504,854		$	330,985		$	835,839
Net income	—			233,634			32,987			266,621
Capital contribution from Westlake Chemical Partner   LP for additional interest	—			—			135,341			135,341
Quarterly distributions	—			(238,009		)	(30,553		)	(268,562		)
Balances at September 30, 2015	$	—		$	500,479		$	468,760		$	969,239

The accompanying notes are an integral part of the combined financial statements.

3

WESTLAKE CHEMICAL OPCO LP

COMBINED STATEMENTS OF CASH FLOWS

(Unaudited)

	Nine Months Ended September 30,
	2015			2014
	(in thousands of dollars)
Cash flows from operating activities
Net income	$	266,621		$	416,737
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	60,637			58,501
Provision for doubtful accounts	170			65
Loss from disposition of fixed assets	278			1,244
Deferred income taxes	(359		)	8,267
Income from equity method investment, net of dividends	—			1,073
Changes in operating assets and liabilities
Accounts receivable—third parties	22,871			(23,637		)
Net accounts receivable—Westlake	(22,233		)	(11,471		)
Inventories	3,362			25,769
Prepaid expenses and other current assets	(170		)	(715		)
Accounts payable	5,117			(8,226		)
Accrued and other liabilities	1,386			7,041
Other, net	(1,466		)	10,498
Net cash provided by operating activities	336,214			485,146
Cash flows from investing activities
Additions to property, plant and equipment	(152,572		)	(144,348		)
Settlements of derivative instruments	—			(133		)
Net cash used for investing activities	(152,572		)	(144,481		)
Cash flows from financing activities
Proceeds from debt payable to Westlake	102,857			141,161
Repayment of debt payable to Westlake	(135,341		)	—
Repayment of debt payable to Westlake with proceeds from the capital contribution from   Westlake Chemical Partners LP	—			(78,940		)
Capital contribution from Westlake Chemical Partners LP for additional interest	135,341			—
Capital contribution from Westlake Chemical Partners LP	—			286,088
Proceeds from capital contribution from Westlake Chemical Partners LP distributed to   Westlake	—			(151,729		)
Net distributions to Westlake prior to initial public offering	—			(448,101		)
Quarterly distributions	(268,562		)	—
Net cash used for financing activities	(165,705		)	(251,521		)
Net increase in cash and cash equivalents	17,937			89,144
Cash and cash equivalents at beginning of period	131,545			—
Cash and cash equivalents at end of period	$	149,482		$	89,144

The accompanying notes are an integral part of the combined financial statements.

4

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS

(Unaudited)

(in thousands of dollars)

1. Description of Business and Basis of Presentation

Description of Business

Westlake Chemical OpCo LP ("OpCo") was formed on May 6, 2014 by Westlake. On August 4, 2014, Westlake Chemical Partners LP (the "Partnership"), a Delaware limited partnership formed in March 2014 completed its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests in OpCo. In connection with the IPO, the Partnership acquired a 10.6% interest in OpCo and a 100% interest in Westlake Chemical OpCo GP LLC ("OpCo GP"), the general partner of OpCo. On April 29, 2015, the Partnership purchased an additional 2.7% newly-issued limited partner interest in OpCo for approximately $135,341, resulting in an aggregate 13.3% limited partner interest in OpCo. OpCo owns three natural gas liquids processing facilities and a common carrier ethylene pipeline. Westlake retains 86.7% noncontrolling interest in OpCo.

Basis of Presentation

The accompanying unaudited combined 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 combined financial statements should be read in conjunction with the December 31, 2014 combined financial statements and notes thereto of OpCo included in the Westlake Chemical Corporation annual report on Form 10-K for the fiscal year ended December 31, 2014 (the "2014 Form 10-K"), filed with the SEC on February 25, 2015. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the combined financial statements of OpCo for the fiscal year ended December 31, 2014.

Unless the context otherwise requires, references in this report to the "Predecessor" refer to Westlake Chemical Partners LP Predecessor, the Partnership's and OpCo's predecessor for accounting purposes and refer to the time periods prior to the IPO. References in this report to OpCo used in the present tense or prospectively refer to the periods subsequent to the IPO. References to "Westlake" refer collectively to Westlake Chemical Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.

Financial information of the Predecessor is derived from the financial statements and accounting records of Westlake. Subsequent to the IPO, OpCo's financial position, results of operations, changes in equity and cash flows consist of the activities and balances of OpCo. The combined financial statements for the three and nine months ended September 30, 2014 were prepared as follows:

• The combined statement of operations for the three months ended September 30, 2014 consists of the results of OpCo for the period from August 4, 2014 through September 30, 2014 and the combined results of the Predecessor for the period from July 1, 2014 through August 3, 2014. The combined statement of operations for the nine months ended September 30, 2014 consists of the results of OpCo for the period from August 4, 2014 through September 30, 2014 and the combined results of the Predecessor for the period from January 1, 2014 through August 3, 2014.

• The combined statement of changes in equity for the nine months ended September 30, 2014 consists of the combined activity for the Predecessor prior to August 4, 2014, and the activity for OpCo completed at and subsequent to the IPO on August 4, 2014.

• The combined statement of cash flows for the nine months ended September 30, 2014 consists of the results of OpCo for the period from August 4, 2014 through September 30, 2014 and the combined results of the Predecessor for the period from January 1, 2014 through August 3, 2014.

In the opinion of management, the accompanying unaudited combined interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of OpCo's financial position as of September 30, 2015, its results of operations for the three and nine months ended September 30, 2015 and 2014 and the changes in its cash position for the nine months ended September 30, 2015 and 2014.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2015 or any other period. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported

5

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ materially 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 July 2015, the FASB deferred the effective date for the revenue recognition standard. The accounting standard will now be effective for reporting periods beginning after December 15, 2017. OpCo is in the process of evaluating the impact that the new accounting guidance will have on its financial position, results of operations and cash flows.

Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items

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

Simplifying the Measurement of Inventory

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

2. Financial Instruments

Cash Equivalents

OpCo had $75,025 and $40,003 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at September 30, 2015 and December 31, 2014, respectively. OpCo's investments in held-to-maturity securities are held at amortized cost, which approximates fair value.

6

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

3. Accounts Receivable—Third Parties

Accounts receivable—third parties consist of the following:

	September 30, 2015			December 31, 2014
Trade customers	$	14,649		$	37,514
Allowance for doubtful accounts	(170		)	—
	14,479			37,514
Other	—			6
Accounts receivable, net—third parties	$	14,479		$	37,520

4. Inventories

Inventories consist of the following:

	September 30, 2015		December 31, 2014
Finished products	$	2,895	$	6,257
Feedstock, additives and chemicals	377		377
Inventories	$	3,272	$	6,634

5. Property, Plant and Equipment

As of September 30, 2015, OpCo had property, plant and equipment, net totaling $962,221. OpCo 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 OpCo 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 $16,231 and $14,900 is included in cost of sales in the combined statements of operations for the three months ended September 30, 2015 and 2014, respectively. Depreciation expense on property, plant and equipment of $48,006 and $45,104 is included in cost of sales in the combined statements of operations for the nine months ended September 30, 2015 and 2014, respectively.

6. Other Assets

Amortization expense on other assets of $4,211 and $4,319 is included in the combined statements of operations for the three months ended September 30, 2015 and 2014, respectively. Amortization expense on other assets of $12,631 and $13,397 is included in the combined statements of operations for the nine months ended September 30, 2015 and 2014, respectively.

7.Related Party Transactions

OpCo regularly enters into related party transactions with Westlake. See below for a description of transactions with related parties.

Sales to Related Parties

OpCo sells ethylene to Westlake under the Ethylene Sales Agreement. Additionally, OpCo from time to time provides other services or products for which it charges Westlake a fee. Prior to the IPO, the Predecessor sold the majority of its ethylene to Westlake for use in Westlake's downstream operations.

7

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

Sales to related parties were as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Net sales—Westlake	$	207,856	$	289,601	$	621,438	$	1,088,561

Cost of Sales from Related Parties

Charges for goods and services purchased by OpCo from Westlake and included in cost of sales relate primarily to feedstock purchased under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement. Prior to the IPO, services provided by Westlake and included in cost of sales related primarily to services provided by employees of Westlake Management Services, Inc., a subsidiary of Westlake. The cost of services provided by employees of Westlake Management Services, Inc. was allocated to the Predecessor's operations primarily on the basis of direct usage.

Charges from related parties in cost of sales were as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Feedstock purchased from Westlake and included in cost   of sales	$	75,752	$	63,108	$	232,584	$	63,108
Other charges from Westlake and included in cost of   sales	20,457		13,879		53,948		47,000
Total	$	96,209	$	76,987	$	286,532	$	110,108

Services from Related Parties Included in Selling, General and Administrative Expenses

Charges for services purchased by OpCo from Westlake and included in selling, general and administrative expenses primarily relate to services Westlake performs on behalf of OpCo under the Omnibus Agreement, including OpCo finance, legal, information technology, human resources, communication, ethics and compliance, and other administrative functions. Prior to the IPO, the Predecessor was allocated costs incurred by Westlake on its behalf for similar functions. These allocations were based primarily on the basis of direct usage when identifiable, with the remainder allocated on the basis of fixed assets, headcount or other measure. Management believes the allocations of expenses incurred by Westlake on the Predecessor's behalf are reasonable and reflect all costs related to the operations of the Predecessor. Nevertheless, the financial information of the Predecessor may not have included all of the expenses that would have been incurred had the Predecessor been a stand-alone company during the periods prior to the IPO.

Charges from related parties included within selling, general and administrative expenses were as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Services received from Westlake and included in selling,   general and administrative expenses	$	4,772	$	3,955	$	14,891	$	15,573

Goods and Services from Related Parties Capitalized as Assets

Charges for goods and services purchased by OpCo from Westlake which were capitalized as assets relate primarily to the services of Westlake employees under the Services and Secondment Agreement. Prior to the IPO, salaries and benefits of Westlake Management Services, Inc. were allocated to the Predecessor primarily on the basis of direct usage.

Charges from related parties for goods and services capitalized as assets were as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Goods and services purchased from Westlake and   capitalized as assets	$	1,304	$	830	$	3,241	$	2,074

8

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

Accounts Receivable from and Accounts Payable to Related Parties

OpCo's accounts receivable from Westlake result primarily from ethylene sales to Westlake under the Ethylene Sales Agreement. OpCo's accounts payable to Westlake result primarily from feedstock purchases under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement and the Omnibus Agreement.

The related party accounts receivable and accounts payable balances were as follows:

	September 30, 2015			December 31, 2014
Accounts receivable, net—Westlake	$	44,035		$	18,529
Accounts payable—Westlake	(8,605		)	(5,332		)

Debt Payable to Related Parties

OpCo assumed promissory notes payable to Westlake and entered into a senior unsecured revolving credit facility with Westlake in connection with the IPO. Prior to the IPO, the Predecessor funded certain capital expenditures through promissory notes payable to Westlake, a portion of which were assumed by OpCo in connection with the IPO. See Note 8 for description of related party debt payable balances. Interest on related party debt payable balances for the three months ended September 30, 2015 and 2014 were $217 and $2,137, respectively, and for the nine months ended September 30, 2015 and 2014 were $2,449 and $9,833, respectively, and are reflected as a component of other income (expense) in the combined statements of operations. Interest capitalized as a component of property, plant and equipment on related party debt was $1,284 for the three months ended September 30, 2015 and $3,394 for the nine months ended September 30, 2015. At September 30, 2015 and December 31, 2014, accrued interest on related party debt was $1,499 and $2,403, respectively, and is reflected as a component of accrued liabilities in the balance sheets.

Debt payable to related parties was as follows:

	September 30, 2015		December 31, 2014
Long-term debt payable to Westlake	$	195,154	$	227,638

General

OpCo, together with other subsidiaries of Westlake not included in these combined financial statements, is a guarantor under Westlake's revolving credit facility and the indentures governing its senior notes. As of September 30, 2015 and December 31, 2014, Westlake had outstanding letters of credit totaling $29,953 and $31,392 under its revolving credit facility and $754,000 and $754,000 outstanding under its senior notes (less the unamortized discount of $803 and $892), respectively.

The indentures governing Westlake's senior notes prevent OpCo from making distributions to the Partnership if any default or event of default (as defined in the indentures) exists. However, Westlake's credit facility does not prevent OpCo from making distributions to the Partnership.

OpCo has entered into two site lease agreements with Westlake in connection with the IPO, and each has a term of 50 years. Pursuant to the site lease agreements, OpCo pays Westlake one dollar per site per year.

8. Long-term Debt Payable to Westlake

Long-term debt payable to Westlake consists of the following:

	September 30, 2015		December 31, 2014
August 2013 Promissory Notes (variable interest rate of prime plus 1.5%, original   scheduled maturity of August 1, 2023)	$	31,775	$	167,116
OpCo Revolver (variable interest rate of London Interbank Offered Rate ("LIBOR") plus   3.0%, original scheduled maturity of August 4, 2019)	163,379		60,522
	$	195,154	$	227,638

9

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

In 2013, three intercompany promissory notes were issued for capital expenditures incurred by Westlake on behalf of the Predecessor's operations (together, the "August 2013 Promissory Notes"). In connection with the IPO, OpCo assumed a portion of the August 2013 Promissory Notes. Proceeds drawn under the August 2013 Promissory Notes during the nine months ended September 30, 2014 were used to fund capital expenditures at the Predecessor's ethylene plants.

In connection with the IPO on August 4, 2014, OpCo entered into a $600,000 senior unsecured revolving credit facility agreement with Westlake (the "OpCo Revolver"). The OpCo Revolver accrues interest quarterly at a rate of LIBOR plus 3.0%, which may be paid-in-kind as an addition to the principal at OpCo's option. Proceeds drawn under the OpCo Revolver during the nine months ended September 30, 2015 were used to fund capital expenditures at OpCo's ethylene plants.

As of September 30, 2015, OpCo was in compliance with all of the covenants under the August 2013 Promissory Note and the OpCo Revolver.

9. Fair Value Measurements

OpCo 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.

There were no assets or liabilities accounted for at fair value on a recurring basis as of September 30, 2015 and December 31, 2014. There were no transfers in or out of Levels 1 and 2 of the fair value hierarchy for the nine months ended September 30, 2015 and 2014.

OpCo has other financial assets and liabilities subject to fair value measures. These financial assets and liabilities include accounts receivable, net, accounts payable and long-term debt payable to Westlake, all of which are recorded at carrying value. The amounts reported in the balance sheets for accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of OpCo's long-term debt at September 30, 2015 and December 31, 2014 are summarized in the table below. OpCo's long-term debt includes the August 2013 Promissory Notes and the OpCo Revolver. The fair value of debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because OpCo's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the OpCo's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the OpCo's long-term debt include the selection of an appropriate discount rate.

	September 30, 2015				December 31, 2014
	Carrying Value		Fair Value		Carrying Value		Fair Value
August 2013 Promissory Notes	$	31,775	$	31,775	$	167,116	$	167,116
OpCo Revolver	163,379		170,613		60,522		60,522

10. Income Taxes

OpCo is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. OpCo is, however, subject to state and local income taxes. The Predecessor's operating results were included in Westlake's U.S. federal and state income tax returns. Amounts presented in the combined financial statements pertaining to the period prior to the IPO relate to income taxes that have been determined on a separate tax return basis and the Predecessor's contribution to Westlake Chemical Corporation's net operating losses and tax credits have been included in the Predecessor's combined financial statements.

The effective income tax rates were 0.2% and 0.2% for the three and nine months ended September 30, 2015, respectively. The effective income tax rates for the three and nine months ended September 30, 2015 are not comparable to the effective income

10

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

tax rate for the prior-year comparative periods as OpCo is not subject to federal income taxes subsequent to the IPO. The effective income tax rate of the Predecessor was 35.4% for the period from January 1, 2014 through August 3, 2014. The effective income tax rate for the 2014 period prior to the IPO was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, mostly offset by the domestic manufacturing deduction and state income tax credits. The OpCo's effective tax rate was less than one percent for the 2014 period subsequent to the IPO.

11.Supplemental Information

Accrued Liabilities

Accrued liabilities were $21,055 and $11,225 at September 30, 2015 and December 31, 2014, respectively. The accrual related to capital expenditures and accrued maintenance, which are components of accrued liabilities, were $14,452 and $2,740, at September 30, 2015, respectively. Accrued taxes, interest on long-term debt and the accrual related to capital expenditures, which are components of accrued liabilities, were $1,622, $2,403, and $5,026 at December 31, 2014, respectively. No other component of accrued liabilities was more than five percent of total current liabilities.

Non-cash Operating Activity

The Predecessor settled $2,089 and $9,530 of its total interest expense incurred on long-term debt payable to Westlake as an addition to principal on debt outstanding for the three and nine months ended September 30, 2014, respectively.

Non-cash Investing Activity

The change in capital expenditure accrual reducing additions to property, plant and equipment was $15,850 for the nine months ended September 30, 2015. The change in capital expenditure accrual reducing additions to property, plant and equipment was $8,564 for the nine months ended September 30, 2014.

12. Major Customer and Concentration of Credit Risk

During the three months ended September 30, 2015 and 2014, Westlake accounted for approximately 83.6% and 73.9%, respectively, of OpCo's and the Predecessor's net sales. During the nine months ended September 30, 2015 and 2014, Westlake accounted for approximately 81.9% and 73.7%, respectively, of OpCo's and the Predecessor's net sales.

13. Commitments and Contingencies

OpCo 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. Because several of OpCo's processing sites have a history of industrial use, it is impossible to predict precisely what effect these legal requirements will have on OpCo. Westlake has agreed to indemnify OpCo for liabilities that occurred or existed prior to August 4, 2014.

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, which is a portion of the B.F. Goodrich superfund site, Goodrich agreed to indemnify Westlake for any liabilities related to preexisting contamination at the site. Westlake agreed to indemnify Goodrich for post-closing contamination caused by Westlake's operations. The soil and groundwater at the site 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 Westlake, 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 100.0% 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 Westlake 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) Westlake and PolyOne would negotiate a new environmental remediation utilities and services agreement to cover Westlake'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 Westlake that have

11

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

been invoiced to PolyOne to provide the environmental remediation services were $2,805 in 2014. By letter dated March 16, 2010, PolyOne notified Westlake that it was initiating an arbitration proceeding under the settlement agreement. In this proceeding, PolyOne seeks to readjust the percentage allocation of costs and to recover approximately $1,400 from Westlake in reimbursement of previously paid remediation costs. The arbitration is currently stayed pending the outcome of discussions between other parties and their insurance carriers.

State Administrative Proceedings. There are several administrative proceedings in Kentucky involving Westlake, Goodrich and PolyOne related to the same manufacturing site in Calvert City, which includes OpCo's processing facility 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 Westlake. Westlake 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. 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 the Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"). In its response to the Cabinet, 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 OpCo'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 Calvert City site. In June 2009, the EPA notified Westlake that Westlake 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. Westlake negotiated, in conjunction with the other potentially responsible parties, an AOC and an order to conduct an RIFS. Due to OpCo's ownership and current operation of the property, OpCo may be subject to additional requirements and liabilities under CERCLA.

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, Westlake received a Clean Air Act Section 114 Information Request from the EPA which sought information regarding flares at the Calvert City and Lake Charles facilities. Westlake submitted information pursuant to such request, including information regarding three flares that OpCo owns. The EPA has informed Westlake 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 Westlake conduct additional flare sampling and provide supplemental information. Westlake is currently in negotiations with the EPA regarding these demands, some of which are applicable to OpCo's flares. The EPA has indicated that it is seeking a consent decree with that would obligate Westlake to take corrective actions relating to the alleged noncompliance. Westlake has not agreed that any flares are out of compliance or that any corrective actions are warranted. Depending on the outcome of Westlake's negotiations with the EPA, additional controls on emissions from OpCo's 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 regarding OpCo's assets, and those of Westlake, for various air compliance issues. OpCo and Westlake are working with LDEQ to settle these claims, and a global settlement of all claims is being discussed. While settlement may result in a total civil penalty of approximately $200, such a settlement will likely cover assets owned by OpCo and Westlake, and to the extent it covers OpCo's assets, Westlake has agreed to indemnify OpCo for liabilities to the extent such liabilities occurred or existed prior to August 4, 2014.

In addition to the matters described above, OpCo is involved in various routine legal proceedings incidental to the conduct of its business. OpCo does not believe that any of these routine legal proceedings will have a material adverse effect on its financial condition, results of operations or cash flows.

12

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

14. Subsequent Events

Subsequent events were evaluated through the date on which the financial statements were issued.

13

XML

Earnings per Share (Tables)

9 Months Ended

Sep. 30, 2015

Earnings Per Share [Abstract]

Schedule Of Net Income Attributable To Common Stockholders

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Net income attributable to    Westlake Chemical Corporation	$	183,604		$	167,757		$	535,041		$	495,232
Less:
Net income attributable to participating securities	(195		)	(353		)	(653		)	(1,099		)
Net income attributable to common shareholders	$	183,409		$	167,404		$	534,388		$	494,133

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 September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Weighted average common shares—basic	131,664,296		133,299,458		132,301,814		133,199,304
Plus incremental shares from:
Assumed exercise of options	456,939		546,601		484,720		543,841
Weighted average common shares—diluted	132,121,235		133,846,059		132,786,534		133,743,145
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.39	$	1.26	$	4.04	$	3.71
Diluted	$	1.39	$	1.25	$	4.02	$	3.69

XML

Long-Term Debt (Revolving Credit Facility) (Details) - Line of Credit	9 Months Ended
	Sep. 30, 2015 USD ($)
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	$ 29,953,000
Remaining borrowing capacity	$ 346,374,000
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%

XML

Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts Receivable, Net [Abstract]
Trade customers	$ 495,318	$ 525,546
Affiliates	0	437
Allowance for doubtful accounts	(13,967)	(13,468)
Receivables from trade customers and affiliates, net	481,351	512,515
Federal and state taxes	19,819	8,919
Other	19,790	39,232
Accounts receivable, net	$ 520,960	$ 560,666

XML

Supplemental Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Accrued Liabilities [Abstract]
Accrued liabilities	$ 290,115		$ 290,115		$ 276,118
Accrued rebates	39,046		39,046		49,900
Accrued incentive compensation	43,151		43,151		37,626
Other Liabilities [Abstract]
Other liabilities	170,770		170,770		174,859
Non-current pension obligation	127,235		127,235		$ 136,296
Other Income and Expenses [Abstract]
Interest income	1,631	$ 341	3,383	$ 2,669
Dividend income	0	0	3,328	0
Foreign exchange currency (losses) gains, net	(731)	(6,450)	1,140	(6,695)
Income from equity method investments	664	3,304	5,278	7,244
Impairment of equity method investment	0	0	(4,925)	0
Gain on acquisition and related expenses, net	0	0	20,430	0
Gain from sales of equity securities	0	0	3,795	0
Other	1,072	135	1,361	1,222
Other income (expense), net	$ 2,636	$ (2,670)	$ 33,790	$ 4,440

XML

Stockholders' Equity (Changes in Stockholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			$ 3,201,888	$ 2,418,603
Net income	$ 188,420	$ 170,156	548,888	497,631
Pension and other post- retirement benefits liability			1,190	383
Foreign currency translation adjustments			(43,746)	(37,882)
Net unrealized holding gains on investments			124	3,682
Common stock repurchased			(122,249)	(9,495)
Shares issued—stock- based compensation			984	5,502
Stock-based compensation, net of tax on stock options exercised			9,996	13,526
Dividends paid			(67,852)	(55,690)
Distributions to noncontrolling interests			(10,982)
Noncontrolling interest in acquired business			1,597
Issuance of Westlake Chemical Partners LP common units				286,088
Amount, ending balance	3,519,838	3,122,348	3,519,838	3,122,348
Common Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			1,347	1,346
Shares issued—stock- based compensation			0	1
Amount, ending balance	1,347	1,347	1,347	1,347
Treasury Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			(96,372)	(46,220)
Common stock repurchased			(122,249)	(9,495)
Shares issued—stock- based compensation			1,079	2,467
Amount, ending balance	(217,542)	(53,248)	(217,542)	(53,248)
Additional Paid-in Capital [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			530,441	511,432
Shares issued—stock- based compensation			(95)	3,034
Stock-based compensation, net of tax on stock options exercised			9,996	13,526
Amount, ending balance	540,342	527,992	540,342	527,992
Retained Earnings [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			2,555,528	1,954,661
Net income			535,041	495,232
Dividends paid			(67,852)	(55,690)
Amount, ending balance	3,022,717	2,394,203	3,022,717	2,394,203
AOCI Attributable to Parent [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			(79,433)	(2,616)
Pension and other post- retirement benefits liability			1,190	383
Foreign currency translation adjustments			(43,746)	(37,882)
Net unrealized holding gains on investments			124	3,682
Amount, ending balance	(121,865)	(36,433)	(121,865)	(36,433)
Noncontrolling Interest [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			290,377	0
Net income			13,847	2,399
Distributions to noncontrolling interests			(10,982)	0
Noncontrolling interest in acquired business			1,597
Issuance of Westlake Chemical Partners LP common units				286,088
Amount, ending balance	$ 294,839	$ 288,487	$ 294,839	$ 288,487

XML

Segment Information (Total Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 5,524,405	$ 5,213,990
Olefins
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,817,303	1,785,895
Vinyls
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,601,263	2,618,646
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,105,839	$ 809,449

XML

Financial Instruments (Available-for-sale Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Current	$ 285,726		$ 285,726		$ 0
Cost	289,268		289,268		15,050
Gross Unrealized Gains	746		746		364
Gross Unrealized Losses	(190)		(190)		0
Fair Value	289,824		289,824		15,414
Net unrealized gains on available-for-sale securities	357		357		233
Income tax on gains from available-for-sale securities	199		199		131
Proceeds from sales and maturities of securities	1,019	$ 0	16,056	$ 342,045
Gross realized gains	0	0	3,795	1,311
Gross realized losses	0	$ 0	0	$ (99)
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	3,804		3,804		15,050
Gross Unrealized Gains	294		294		364
Gross Unrealized Losses	0		0		0
Fair Value	4,098		4,098		$ 15,414
Corporate bond securities
Schedule of Available-for-sale Securities [Line Items]
Cost	194,310		194,310
Gross Unrealized Gains	306		306
Gross Unrealized Losses	(171)		(171)
Fair Value	194,445		194,445
US Treasury and Government
Schedule of Available-for-sale Securities [Line Items]
Cost	55,073		55,073
Gross Unrealized Gains	80		80
Gross Unrealized Losses	(2)		(2)
Fair Value	55,151		55,151
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Cost	36,081		36,081
Gross Unrealized Gains	66		66
Gross Unrealized Losses	(17)		(17)
Fair Value	$ 36,130		$ 36,130

XML

Accounts and Notes Payable (Tables)

9 Months Ended

Sep. 30, 2015

Accounts and Notes Payable [Abstract]

Schedule of Accounts Payable and Accrued Liabilities

	September 30, 2015		December 31, 2014
Accounts payable	$	237,622	$	261,062
Notes payable to banks	7,150		—
Accounts and notes payable	$	244,772	$	261,062

XML

Guarantor Disclosures (Additional Information) (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Condensed Financial Statements, Captions [Line Items]
Less than percentage owned in subsidiary	100.00%
3.60% Senior Notes Due 2022
Condensed Financial Statements, Captions [Line Items]
Stated interest rate	3.60%
Maturity	2022
Minimum debt amount guaranteed by subsidiaries	$ 5,000

XML

Insurance Recovery (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Insurance Recovery [Abstract]
Insurance recovery	$ 3,347	$ 7,809

XML

Stockholders' Equity (Reclassifications in AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of benefits liability	$ 692		$ 240		$ 2,019		$ 685
Realized gain on available-for-sale investments	2,636		(2,670)		33,790		4,440
Provision for income taxes	(60,033)		(124,449)		(236,824)		(300,231)
Net income attributable to Westlake Chemical Corporation	183,604		167,757		535,041		495,232
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income attributable to Westlake Chemical Corporation	(451)		(148)		1,114		355
Accumulated Defined Benefit Plans Adjustment | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service costs	0	[1]	(87)	[1]	0	[1]	(261)
Amortization of benefits liability	(692)	[1]	(153)	[1]	(2,019)	[1]	(424)
(Loss) income before income taxes	(692)		(240)		(2,019)		(685)
Provision for income taxes	241		92		701		263
Net income attributable to Westlake Chemical Corporation	(451)		(148)		(1,318)		(422)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Realized gain on available-for-sale investments	0		0		3,795		1,212
Provision for income taxes	0		0		(1,363)		(435)
Net income attributable to Westlake Chemical Corporation	$ 0		$ 0		$ 2,432		$ 777

[1] These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 10 (Employee Benefits) to the financial statements included in the 2014 Form 10-K.

XML

Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Net external sales	$ 1,188,037	$ 1,253,227	$ 3,476,570	$ 3,279,479
Income (loss) from operations	254,028	306,761	778,682	821,604
Depreciation and amortization	61,248	53,920	180,229	148,394
Other income (expense), net	2,636	(2,670)	33,790	4,440
Provision for (benefit from) income taxes	60,033	124,449	236,824	300,231
Capital expenditures	125,304	94,271	329,236	311,183
Olefins
Segment Reporting Information [Line Items]
Net external sales	588,097	703,097	1,792,052	2,124,948
Income (loss) from operations	196,703	259,277	608,744	770,267
Depreciation and amortization	27,678	26,443	82,240	79,811
Other income (expense), net	1,323	1,609	3,770	4,262
Provision for (benefit from) income taxes	45,865	105,030	186,534	282,082
Capital expenditures	69,885	48,519	206,719	121,041
Vinyls
Segment Reporting Information [Line Items]
Net external sales	599,940	550,130	1,684,518	1,154,531
Income (loss) from operations	67,779	59,445	202,831	76,460
Depreciation and amortization	33,432	27,336	97,615	68,127
Other income (expense), net	10	1,189	6,927	942
Provision for (benefit from) income taxes	15,812	21,761	55,270	22,121
Capital expenditures	53,510	44,067	114,935	187,449
Corporate and Other
Segment Reporting Information [Line Items]
Income (loss) from operations	(10,454)	(11,961)	(32,893)	(25,123)
Depreciation and amortization	138	141	374	456
Other income (expense), net	1,303	(5,468)	23,093	(764)
Provision for (benefit from) income taxes	(1,644)	(2,342)	(4,980)	(3,972)
Capital expenditures	1,909	1,685	7,582	2,693
Polyethylene | Olefins
Segment Reporting Information [Line Items]
Net external sales	423,631	498,450	1,283,545	1,461,097
Ethylene, Styrene And Other | Olefins
Segment Reporting Information [Line Items]
Net external sales	164,466	204,647	508,507	663,851
PVC, Caustic Soda And Other | Vinyls
Segment Reporting Information [Line Items]
Net external sales	468,235	416,771	1,315,101	776,060
Building Products | Vinyls
Segment Reporting Information [Line Items]
Net external sales	131,705	133,359	369,417	378,471
Intersegment sales
Segment Reporting Information [Line Items]
Net external sales	28,892	26,873	79,752	119,182
Intersegment sales | Olefins
Segment Reporting Information [Line Items]
Net external sales	28,551	26,518	78,654	118,153
Intersegment sales | Vinyls
Segment Reporting Information [Line Items]
Net external sales	$ 341	$ 355	$ 1,098	$ 1,029

XML

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,188,037	$ 1,253,227	$ 3,476,570	$ 3,279,479
Cost of sales	876,761	891,707	2,527,567	2,324,978
Gross profit	311,276	361,520	949,003	954,501
Selling, general and administrative expenses	57,248	54,759	170,321	132,897
Income from operations	254,028	306,761	778,682	821,604
Interest expense	(8,211)	(9,486)	(26,760)	(28,182)
Other income, net	2,636	(2,670)	33,790	4,440
Income before income taxes	248,453	294,605	785,712	797,862
Provision for (benefit from) income taxes	60,033	124,449	236,824	300,231
Equity in net income of subsidiaries	0	0	0	0
Net income	188,420	170,156	548,888	497,631
Net income attributable to noncontrolling interests	4,816	2,399	13,847	2,399
Net income attributable to Westlake Chemical Corporation	183,604	167,757	535,041	495,232
Comprehensive income (loss) attributable to Westlake Chemical Corporation	181,663	131,456	492,609	461,415
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	804	399	1,617	1,474
Income from operations	(804)	(399)	(1,617)	(1,474)
Interest expense	(10,405)	(10,343)	(31,726)	(29,032)
Other income, net	1,239	2,138	17,627	14,488
Income before income taxes	(9,970)	(8,604)	(15,716)	(16,018)
Provision for (benefit from) income taxes	(3,249)	(3,088)	(5,226)	(5,686)
Equity in net income of subsidiaries	190,325	173,273	545,531	505,564
Net income	183,604	167,757	535,041	495,232
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Westlake Chemical Corporation	183,604	167,757	535,041	495,232
Comprehensive income (loss) attributable to Westlake Chemical Corporation	181,663	131,456	492,609	461,415
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	961,036	1,026,282	2,862,400	2,809,844
Cost of sales	774,726	831,675	2,260,454	2,476,608
Gross profit	186,310	194,607	601,946	333,236
Selling, general and administrative expenses	41,429	36,445	127,794	123,050
Income from operations	144,881	158,162	474,152	210,186
Interest expense	(3)	(2)	(8)	(8)
Other income, net	3,971	(2,942)	(2,574)	(1,729)
Income before income taxes	148,849	155,218	471,570	208,449
Provision for (benefit from) income taxes	56,372	93,366	231,542	109,920
Equity in net income of subsidiaries	76,945	113,157	233,635	410,875
Net income	169,422	175,009	473,663	509,404
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Westlake Chemical Corporation	169,422	175,009	473,663	509,404
Comprehensive income (loss) attributable to Westlake Chemical Corporation	169,673	175,137	474,292	509,787
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Net sales	248,619	392,008	758,715	1,476,157
Cost of sales	154,474	227,015	473,815	832,304
Gross profit	94,145	164,993	284,900	643,853
Selling, general and administrative expenses	4,941	8,014	15,178	21,957
Income from operations	89,204	156,979	269,722	621,896
Interest expense	(217)	(2,137)	(2,449)	(9,833)
Other income, net	(124)	486	(85)	3,135
Income before income taxes	88,863	155,328	267,188	615,198
Provision for (benefit from) income taxes	141	36,309	567	198,461
Equity in net income of subsidiaries	0	0	0	0
Net income	88,722	119,019	266,621	416,737
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Westlake Chemical Corporation	88,722	119,019	266,621	416,737
Comprehensive income (loss) attributable to Westlake Chemical Corporation	88,722	119,019	266,621	416,737
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	288,211	208,313	784,219	229,183
Cost of sales	252,618	202,110	707,171	221,233
Gross profit	35,593	6,203	77,048	7,950
Selling, general and administrative expenses	14,846	14,184	40,623	16,954
Income from operations	20,747	(7,981)	36,425	(9,004)
Interest expense	(95)	(39)	(190)	(39)
Other income, net	59	683	26,435	(724)
Income before income taxes	20,711	(7,337)	62,670	(9,767)
Provision for (benefit from) income taxes	6,769	(2,138)	9,941	(2,464)
Equity in net income of subsidiaries	11,777	5,862	32,986	5,862
Net income	25,719	663	85,715	(1,441)
Net income attributable to noncontrolling interests	4,816	2,399	13,847	2,399
Net income attributable to Westlake Chemical Corporation	20,903	(1,736)	71,868	(3,840)
Comprehensive income (loss) attributable to Westlake Chemical Corporation	19,170	(39,528)	28,683	(41,722)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(309,829)	(373,376)	(928,764)	(1,235,705)
Cost of sales	(305,057)	(369,093)	(913,873)	(1,205,167)
Gross profit	(4,772)	(4,283)	(14,891)	(30,538)
Selling, general and administrative expenses	(4,772)	(4,283)	(14,891)	(30,538)
Income from operations	0	0	0	0
Interest expense	2,509	3,035	7,613	10,730
Other income, net	(2,509)	(3,035)	(7,613)	(10,730)
Income before income taxes	0	0	0	0
Provision for (benefit from) income taxes	0	0	0	0
Equity in net income of subsidiaries	(279,047)	(292,292)	(812,152)	(922,301)
Net income	(279,047)	(292,292)	(812,152)	(922,301)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Westlake Chemical Corporation	(279,047)	(292,292)	(812,152)	(922,301)
Comprehensive income (loss) attributable to Westlake Chemical Corporation	$ (277,565)	$ (254,628)	$ (769,596)	$ (884,802)

XML

Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting [Abstract]
Income from operations	$ 254,028	$ 306,761	$ 778,682	$ 821,604
Interest expense	(8,211)	(9,486)	(26,760)	(28,182)
Other income, net	2,636	(2,670)	33,790	4,440
Income before income taxes	$ 248,453	$ 294,605	$ 785,712	$ 797,862

XML

Acquisition (Narrative) (Details) $ in Thousands, lb in Millions	Jun. 01, 2015 USD ($) lb
Suzhou Huasu Plastics Company Ltd [Member]
Business Acquisition [Line Items]
Net gains (loss) on fair value remeasurement	$ (1,505)
Fair value of consideration transferred-cash	5,518
Bargain purchase gain on acquisition	22,550
Fair value of accounts receivable	2,515
Gross contractual amount of accounts receivable	3,006
Uncollectible accounts receivable	$ (491)
PVC Resin Member [Member] | Suzhou Huasu Plastics Company Ltd [Member]
Business Acquisition [Line Items]
Combined annual capacity | lb	300
PVC Film [Member] | Suzhou Huasu Plastics Company Ltd [Member]
Business Acquisition [Line Items]
Combined annual capacity | lb	145
Building Products [Member] | Suzhou Huasu Plastics Company Ltd [Member]
Business Acquisition [Line Items]
Combined annual capacity | lb	33
Affiliated Entity [Member] | Suzhou Huasu Plastics Company Ltd [Member]
Business Acquisition [Line Items]
Percentage of interest acquired	35.70%
Percentage of interest	95.00%
Ownership interest	59.30%

XML

Commitments and Contingencies

9 Months Ended

Sep. 30, 2015

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 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 $2,805 in 2014. 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 seeks to readjust the percentage allocation of costs and to recover approximately $1,400 from the Company in reimbursement of previously paid remediation costs. The arbitration is currently stayed.

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. Such global settlement may result in a total civil penalty of approximately $200.

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.

XML

Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, plant and equipment	$ 2,916,630		$ 2,916,630		$ 2,757,557
Depreciation expense on property, plant and equipment	$ 52,208	$ 45,080	$ 153,129	$ 123,000

XML

Segment Information (Tables)

9 Months Ended

Sep. 30, 2015

Segment Reporting [Abstract]

Segment Reporting Information

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Net external sales
Olefins
Polyethylene	$	423,631		$	498,450		$	1,283,545		$	1,461,097
Styrene, feedstock and other	164,466			204,647			508,507			663,851
Total Olefins	588,097			703,097			1,792,052			2,124,948
Vinyls
PVC, caustic soda and other	468,235			416,771			1,315,101			776,060
Building products	131,705			133,359			369,417			378,471
Total Vinyls	599,940			550,130			1,684,518			1,154,531
	$	1,188,037		$	1,253,227		$	3,476,570		$	3,279,479
Intersegment sales
Olefins	$	28,551		$	26,518		$	78,654		$	118,153
Vinyls	341			355			1,098			1,029
	$	28,892		$	26,873		$	79,752		$	119,182
Income (loss) from operations
Olefins	$	196,703		$	259,277		$	608,744		$	770,267
Vinyls	67,779			59,445			202,831			76,460
Corporate and other	(10,454		)	(11,961		)	(32,893		)	(25,123		)
	$	254,028		$	306,761		$	778,682		$	821,604
Depreciation and amortization
Olefins	$	27,678		$	26,443		$	82,240		$	79,811
Vinyls	33,432			27,336			97,615			68,127
Corporate and other	138			141			374			456
	$	61,248		$	53,920		$	180,229		$	148,394
Other income (expense), net
Olefins	$	1,323		$	1,609		$	3,770		$	4,262
Vinyls	10			1,189			6,927			942
Corporate and other	1,303			(5,468		)	23,093			(764		)
	$	2,636		$	(2,670	)	$	33,790		$	4,440
Provision for (benefit from) income taxes
Olefins	$	45,865		$	105,030		$	186,534		$	282,082
Vinyls	15,812			21,761			55,270			22,121
Corporate and other	(1,644		)	(2,342		)	(4,980		)	(3,972		)
	$	60,033		$	124,449		$	236,824		$	300,231
Capital expenditures
Olefins	$	69,885		$	48,519		$	206,719		$	121,041
Vinyls	53,510			44,067			114,935			187,449
Corporate and other	1,909			1,685			7,582			2,693
	$	125,304		$	94,271		$	329,236		$	311,183

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 September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Income from operations	$	254,028		$	306,761		$	778,682		$	821,604
Interest expense	(8,211		)	(9,486		)	(26,760		)	(28,182		)
Other income (expense), net	2,636			(2,670		)	33,790			4,440
Income before income taxes	$	248,453		$	294,605		$	785,712		$	797,862

Total Assets

	September 30, 2015		December 31, 2014
Total assets
Olefins	$	1,817,303	$	1,785,895
Vinyls	2,601,263		2,618,646
Corporate and other	1,105,839		809,449
	$	5,524,405	$	5,213,990

XML

Segment Information (Additional Information) (Detail)	9 Months Ended
	Sep. 30, 2015 Segment
Segment Reporting [Abstract]
Number of segments	2

XML

Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2015

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
		September 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	2,722	$	3,145
Commodity forward contracts	Deferred charges and    other assets, net	2,017		—
Total derivative assets		$	4,739	$	3,145

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		September 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	5,421	$	6,549
Commodity forward contracts	Other liabilities	9,846		3,559
Total derivative liabilities		$	15,267	$	10,108

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 September 30,						Nine Months Ended September 30,
		2015			2014			2015			2014
Commodity forward contracts	Gross profit	$	(9,314	)	$	(6,937	)	$	(4,478	)	$	(7,308	)

XML

Accounts and Notes Payable (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts and Notes Payable [Abstract]
Accounts payable	$ 237,622	$ 261,062
Notes payable to banks	7,150	0
Accounts and notes payable	$ 244,772	$ 261,062

XML

Earnings per Share (Additional Information) (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Number of options excluded from computation of diluted earnings per share	315,285	0	295,825	0

XML

Derivative Instruments (Textual) (Detail) - instrument	Sep. 30, 2015	Sep. 30, 2014
Commodity Forward Contracts [Member] | Designated As Fair Value Hedges
Derivative [Line Items]
Number of derivative instruments	0	0

XML

Financial Instruments (Maturity Periods for Investments) (Details)	9 Months Ended
	Sep. 30, 2015
Corporate bond securities | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	2 months
Corporate bond securities | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	3 years
US Government Agencies Debt Securities | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	4 months
US Government Agencies Debt Securities | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	3 years
Mortgage backed securities | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	5 years
Mortgage backed securities | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	6 years
Asset-backed securities | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	1 year
Asset-backed securities | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	26 years

XML

Accounts Receivable

9 Months Ended

Sep. 30, 2015

Accounts Receivable, Net [Abstract]

Accounts Receivable

Accounts Receivable

Accounts receivable consist of the following:

	September 30, 2015			December 31, 2014
Trade customers	$	495,318		$	525,546
Affiliates	—			437
Allowance for doubtful accounts	(13,967		)	(13,468		)
	481,351			512,515
Federal and state taxes	19,819			8,919
Other	19,790			39,232
Accounts receivable, net	$	520,960		$	560,666

XML

Derivative Instruments (Fair Values of Derivative Instruments in Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accrued liabilities
Derivatives, Fair Value [Line Items]
Total derivative liabilities	$ 15,267	$ 10,108
Accounts receivable, net
Derivatives, Fair Value [Line Items]
Total derivative assets	4,739	3,145
Forward Contracts [Member] | Accrued liabilities
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Liabilities	5,421	6,549
Forward Contracts [Member] | Accounts receivable, net
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Assets	2,722	3,145
Forward Contracts [Member] | Deferred charges and other assets, net
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Assets	2,017	0
Commodity Forward Contracts [Member] | Other liabilities
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Liabilities	$ 9,846	$ 3,559

XML

Guarantor Disclosures (Tables)

9 Months Ended

Sep. 30, 2015

Guarantees [Abstract]

Condensed Consolidating Financial Information Balance Sheet

Condensed Consolidating Financial Information as of September 30, 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	$	647,646	$	5,445	$	149,482	$	159,352	$	—		$	961,925
Marketable securities	285,726		—		—		—		—			285,726
Accounts receivable, net	9,371		2,165,248		58,514		135,837		(1,848,010		)	520,960
Inventories	—		333,553		3,272		93,181		—			430,006
Prepaid expenses and other current assets	1,355		15,244		382		3,576		(2,285		)	18,272
Deferred income taxes	441		30,529		—		647		(76		)	31,541
Total current assets	944,539		2,550,019		211,650		392,593		(1,850,371		)	2,248,430
Property, plant and equipment, net	—		1,533,456		962,221		420,953		—			2,916,630
Equity investments	4,879,268		1,204,734		—		468,760		(6,543,169		)	9,593
Other assets, net	17,541		353,506		46,542		133,196		(201,033		)	349,752
Total assets	$	5,841,348	$	5,641,715	$	1,220,413	$	1,415,502	$	(8,594,573	)	$	5,524,405
Current liabilities
Accounts and notes payable	$	1,847,047	$	131,438	$	33,476	$	80,685	$	(1,847,874	)	$	244,772
Accrued liabilities	16,105		168,569		21,055		86,883		(2,497		)	290,115
Total current liabilities	1,863,152		300,007		54,531		167,568		(1,850,371		)	534,887
Long-term debt	753,197		10,889		195,154		—		(195,154		)	764,086
Deferred income taxes	—		503,102		1,489		36,112		(5,879		)	534,824
Other liabilities	—		49,174		—		121,596		—			170,770
Total liabilities	2,616,349		863,172		251,174		325,276		(2,051,404		)	2,004,567
Total Westlake Chemical Corporation stockholders' equity	3,224,999		4,778,543		969,239		795,387		(6,543,169		)	3,224,999
Noncontrolling interests	—		—		—		294,839		—			294,839
Total equity	3,224,999		4,778,543		969,239		1,090,226		(6,543,169		)	3,519,838
Total liabilities and equity	$	5,841,348	$	5,641,715	$	1,220,413	$	1,415,502	$	(8,594,573	)	$	5,524,405

Condensed Consolidating Financial Information as of December 31, 2014

	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	$	655,947	$	3,057	$	131,545	$	90,052	$	—		$	880,601
Accounts receivable, net	8,451		1,454,709		56,049		135,133		(1,093,676		)	560,666
Inventories	—		414,975		6,634		104,167		—			525,776
Prepaid expenses and other current assets	172		9,485		212		1,938		—			11,807
Deferred income taxes	409		29,832		—		2,196		—			32,437
Total current assets	664,979		1,912,058		194,440		333,486		(1,093,676		)	2,011,287
Property, plant and equipment, net	—		1,477,515		842,057		437,985		—			2,757,557
Equity investments	4,033,378		1,237,080		—		352,550		(5,561,703		)	61,305
Other assets, net	30,543		387,325		57,733		141,948		(233,708		)	383,841
Total assets	$	4,728,900	$	5,013,978	$	1,094,230	$	1,265,969	$	(6,889,087	)	$	5,213,990
Current liabilities
Accounts payable	$	1,055,527	$	160,834	$	17,680	$	95,856	$	(1,068,835	)	$	261,062
Accrued liabilities	8,754		203,608		11,225		77,372		(24,841		)	276,118
Total current liabilities	1,064,281		364,442		28,905		173,228		(1,093,676		)	537,180
Long-term debt	753,108		10,889		227,638		—		(227,638		)	763,997
Deferred income taxes	—		497,919		1,848		42,369		(6,070		)	536,066
Other liabilities	—		43,452		—		131,407		—			174,859
Total liabilities	1,817,389		916,702		258,391		347,004		(1,327,384		)	2,012,102
Total Westlake Chemical Corporation stockholders' equity	2,911,511		4,097,276		835,839		628,588		(5,561,703		)	2,911,511
Noncontrolling interests	—		—		—		290,377		—			290,377
Total equity	2,911,511		4,097,276		835,839		918,965		(5,561,703		)	3,201,888
Total liabilities and equity	$	4,728,900	$	5,013,978	$	1,094,230	$	1,265,969	$	(6,889,087	)	$	5,213,990

Condensed Consolidating Financial Information Statement Of Operations

Condensed Consolidating Financial Information for the Three Months Ended September 30, 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	$	—		$	961,036		$	248,619		$	288,211		$	(309,829	)	$	1,188,037
Cost of sales	—			774,726			154,474			252,618			(305,057		)	876,761
Gross profit	—			186,310			94,145			35,593			(4,772		)	311,276
Selling, general and administrative expenses	804			41,429			4,941			14,846			(4,772		)	57,248
(Loss) income from operations	(804		)	144,881			89,204			20,747			—			254,028
Interest expense	(10,405		)	(3		)	(217		)	(95		)	2,509			(8,211		)
Other income (expense), net	1,239			3,971			(124		)	59			(2,509		)	2,636
(Loss) income before income taxes	(9,970		)	148,849			88,863			20,711			—			248,453
(Benefit from) provision for income taxes	(3,249		)	56,372			141			6,769			—			60,033
Equity in net income of subsidiaries	190,325			76,945			—			11,777			(279,047		)	—
Net income	183,604			169,422			88,722			25,719			(279,047		)	188,420
Net income attributable to noncontrolling interests	—			—			—			4,816			—			4,816
Net income attributable to Westlake Chemical Corporation	$	183,604		$	169,422		$	88,722		$	20,903		$	(279,047	)	$	183,604
Comprehensive income attributable to    Westlake Chemical Corporation	$	181,663		$	169,673		$	88,722		$	19,170		$	(277,565	)	$	181,663

Condensed Consolidating Financial Information for the Three Months Ended September 30, 2014

	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			OpCo (Less Than 100% Owned Guarantor Subsidiary)			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	1,026,282		$	392,008		$	208,313		$	(373,376	)	$	1,253,227
Cost of sales	—			831,675			227,015			202,110			(369,093		)	891,707
Gross profit	—			194,607			164,993			6,203			(4,283		)	361,520
Selling, general and administrative expenses	399			36,445			8,014			14,184			(4,283		)	54,759
(Loss) income from operations	(399		)	158,162			156,979			(7,981		)	—			306,761
Interest expense	(10,343		)	(2		)	(2,137		)	(39		)	3,035			(9,486		)
Other income (expense), net	2,138			(2,942		)	486			683			(3,035		)	(2,670		)
(Loss) income before income taxes	(8,604		)	155,218			155,328			(7,337		)	—			294,605
(Benefit from) provision for income taxes	(3,088		)	93,366			36,309			(2,138		)	—			124,449
Equity in net income of subsidiaries	173,273			113,157			—			5,862			(292,292		)	—
Net income	167,757			175,009			119,019			663			(292,292		)	170,156
Net income attributable to noncontrolling interests	—			—			—			2,399			—			2,399
Net income (loss) attributable to Westlake Chemical Corporation	$	167,757		$	175,009		$	119,019		$	(1,736	)	$	(292,292	)	$	167,757
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	131,456		$	175,137		$	119,019		$	(39,528	)	$	(254,628	)	$	131,456

Condensed Consolidating Financial Information Statement Of Cash Flows

Condensed Consolidating Financial Information as of September 30, 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	$	647,646	$	5,445	$	149,482	$	159,352	$	—		$	961,925
Marketable securities	285,726		—		—		—		—			285,726
Accounts receivable, net	9,371		2,165,248		58,514		135,837		(1,848,010		)	520,960
Inventories	—		333,553		3,272		93,181		—			430,006
Prepaid expenses and other current assets	1,355		15,244		382		3,576		(2,285		)	18,272
Deferred income taxes	441		30,529		—		647		(76		)	31,541
Total current assets	944,539		2,550,019		211,650		392,593		(1,850,371		)	2,248,430
Property, plant and equipment, net	—		1,533,456		962,221		420,953		—			2,916,630
Equity investments	4,879,268		1,204,734		—		468,760		(6,543,169		)	9,593
Other assets, net	17,541		353,506		46,542		133,196		(201,033		)	349,752
Total assets	$	5,841,348	$	5,641,715	$	1,220,413	$	1,415,502	$	(8,594,573	)	$	5,524,405
Current liabilities
Accounts and notes payable	$	1,847,047	$	131,438	$	33,476	$	80,685	$	(1,847,874	)	$	244,772
Accrued liabilities	16,105		168,569		21,055		86,883		(2,497		)	290,115
Total current liabilities	1,863,152		300,007		54,531		167,568		(1,850,371		)	534,887
Long-term debt	753,197		10,889		195,154		—		(195,154		)	764,086
Deferred income taxes	—		503,102		1,489		36,112		(5,879		)	534,824
Other liabilities	—		49,174		—		121,596		—			170,770
Total liabilities	2,616,349		863,172		251,174		325,276		(2,051,404		)	2,004,567
Total Westlake Chemical Corporation stockholders' equity	3,224,999		4,778,543		969,239		795,387		(6,543,169		)	3,224,999
Noncontrolling interests	—		—		—		294,839		—			294,839
Total equity	3,224,999		4,778,543		969,239		1,090,226		(6,543,169		)	3,519,838
Total liabilities and equity	$	5,841,348	$	5,641,715	$	1,220,413	$	1,415,502	$	(8,594,573	)	$	5,524,405

Condensed Consolidating Financial Information as of December 31, 2014

	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	$	655,947	$	3,057	$	131,545	$	90,052	$	—		$	880,601
Accounts receivable, net	8,451		1,454,709		56,049		135,133		(1,093,676		)	560,666
Inventories	—		414,975		6,634		104,167		—			525,776
Prepaid expenses and other current assets	172		9,485		212		1,938		—			11,807
Deferred income taxes	409		29,832		—		2,196		—			32,437
Total current assets	664,979		1,912,058		194,440		333,486		(1,093,676		)	2,011,287
Property, plant and equipment, net	—		1,477,515		842,057		437,985		—			2,757,557
Equity investments	4,033,378		1,237,080		—		352,550		(5,561,703		)	61,305
Other assets, net	30,543		387,325		57,733		141,948		(233,708		)	383,841
Total assets	$	4,728,900	$	5,013,978	$	1,094,230	$	1,265,969	$	(6,889,087	)	$	5,213,990
Current liabilities
Accounts payable	$	1,055,527	$	160,834	$	17,680	$	95,856	$	(1,068,835	)	$	261,062
Accrued liabilities	8,754		203,608		11,225		77,372		(24,841		)	276,118
Total current liabilities	1,064,281		364,442		28,905		173,228		(1,093,676		)	537,180
Long-term debt	753,108		10,889		227,638		—		(227,638		)	763,997
Deferred income taxes	—		497,919		1,848		42,369		(6,070		)	536,066
Other liabilities	—		43,452		—		131,407		—			174,859
Total liabilities	1,817,389		916,702		258,391		347,004		(1,327,384		)	2,012,102
Total Westlake Chemical Corporation stockholders' equity	2,911,511		4,097,276		835,839		628,588		(5,561,703		)	2,911,511
Noncontrolling interests	—		—		—		290,377		—			290,377
Total equity	2,911,511		4,097,276		835,839		918,965		(5,561,703		)	3,201,888
Total liabilities and equity	$	4,728,900	$	5,013,978	$	1,094,230	$	1,265,969	$	(6,889,087	)	$	5,213,990

Condensed Consolidating Financial Information for the Three Months Ended September 30, 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	$	—		$	961,036		$	248,619		$	288,211		$	(309,829	)	$	1,188,037
Cost of sales	—			774,726			154,474			252,618			(305,057		)	876,761
Gross profit	—			186,310			94,145			35,593			(4,772		)	311,276
Selling, general and administrative expenses	804			41,429			4,941			14,846			(4,772		)	57,248
(Loss) income from operations	(804		)	144,881			89,204			20,747			—			254,028
Interest expense	(10,405		)	(3		)	(217		)	(95		)	2,509			(8,211		)
Other income (expense), net	1,239			3,971			(124		)	59			(2,509		)	2,636
(Loss) income before income taxes	(9,970		)	148,849			88,863			20,711			—			248,453
(Benefit from) provision for income taxes	(3,249		)	56,372			141			6,769			—			60,033
Equity in net income of subsidiaries	190,325			76,945			—			11,777			(279,047		)	—
Net income	183,604			169,422			88,722			25,719			(279,047		)	188,420
Net income attributable to noncontrolling interests	—			—			—			4,816			—			4,816
Net income attributable to Westlake Chemical Corporation	$	183,604		$	169,422		$	88,722		$	20,903		$	(279,047	)	$	183,604
Comprehensive income attributable to    Westlake Chemical Corporation	$	181,663		$	169,673		$	88,722		$	19,170		$	(277,565	)	$	181,663

Condensed Consolidating Financial Information for the Three Months Ended September 30, 2014

	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			OpCo (Less Than 100% Owned Guarantor Subsidiary)			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	1,026,282		$	392,008		$	208,313		$	(373,376	)	$	1,253,227
Cost of sales	—			831,675			227,015			202,110			(369,093		)	891,707
Gross profit	—			194,607			164,993			6,203			(4,283		)	361,520
Selling, general and administrative expenses	399			36,445			8,014			14,184			(4,283		)	54,759
(Loss) income from operations	(399		)	158,162			156,979			(7,981		)	—			306,761
Interest expense	(10,343		)	(2		)	(2,137		)	(39		)	3,035			(9,486		)
Other income (expense), net	2,138			(2,942		)	486			683			(3,035		)	(2,670		)
(Loss) income before income taxes	(8,604		)	155,218			155,328			(7,337		)	—			294,605
(Benefit from) provision for income taxes	(3,088		)	93,366			36,309			(2,138		)	—			124,449
Equity in net income of subsidiaries	173,273			113,157			—			5,862			(292,292		)	—
Net income	167,757			175,009			119,019			663			(292,292		)	170,156
Net income attributable to noncontrolling interests	—			—			—			2,399			—			2,399
Net income (loss) attributable to Westlake Chemical Corporation	$	167,757		$	175,009		$	119,019		$	(1,736	)	$	(292,292	)	$	167,757
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	131,456		$	175,137		$	119,019		$	(39,528	)	$	(254,628	)	$	131,456

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 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	$	—		$	2,862,400		$	758,715		$	784,219		$	(928,764	)	$	3,476,570
Cost of sales	—			2,260,454			473,815			707,171			(913,873		)	2,527,567
Gross profit	—			601,946			284,900			77,048			(14,891		)	949,003
Selling, general and administrative expenses	1,617			127,794			15,178			40,623			(14,891		)	170,321
(Loss) income from operations	(1,617		)	474,152			269,722			36,425			—			778,682
Interest expense	(31,726		)	(8		)	(2,449		)	(190		)	7,613			(26,760		)
Other income (expense), net	17,627			(2,574		)	(85		)	26,435			(7,613		)	33,790
(Loss) income before income taxes	(15,716		)	471,570			267,188			62,670			—			785,712
(Benefit from) provision for income taxes	(5,226		)	231,542			567			9,941			—			236,824
Equity in net income of subsidiaries	545,531			233,635			—			32,986			(812,152		)	—
Net income	535,041			473,663			266,621			85,715			(812,152		)	548,888
Net income attributable to noncontrolling interests	—			—			—			13,847			—			13,847
Net income attributable to Westlake Chemical Corporation	$	535,041		$	473,663		$	266,621		$	71,868		$	(812,152	)	$	535,041
Comprehensive income attributable to    Westlake Chemical Corporation	$	492,609		$	474,292		$	266,621		$	28,683		$	(769,596	)	$	492,609

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2014

	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries			OpCo (Less Than 100% Owned Guarantor Subsidiary)			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	2,809,844		$	1,476,157		$	229,183		$	(1,235,705	)	$	3,279,479
Cost of sales	—			2,476,608			832,304			221,233			(1,205,167		)	2,324,978
Gross profit	—			333,236			643,853			7,950			(30,538		)	954,501
Selling, general and administrative expenses	1,474			123,050			21,957			16,954			(30,538		)	132,897
(Loss) income from operations	(1,474		)	210,186			621,896			(9,004		)	—			821,604
Interest expense	(29,032		)	(8		)	(9,833		)	(39		)	10,730			(28,182		)
Other income (expense), net	14,488			(1,729		)	3,135			(724		)	(10,730		)	4,440
(Loss) income before income taxes	(16,018		)	208,449			615,198			(9,767		)	—			797,862
(Benefit from) provision for income taxes	(5,686		)	109,920			198,461			(2,464		)	—			300,231
Equity in net income of subsidiaries	505,564			410,875			—			5,862			(922,301		)	—
Net income (loss)	495,232			509,404			416,737			(1,441		)	(922,301		)	497,631
Net income attributable to noncontrolling interests	—			—			—			2,399			—			2,399
Net income (loss) attributable to Westlake Chemical Corporation	$	495,232		$	509,404		$	416,737		$	(3,840	)	$	(922,301	)	$	495,232
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	461,415		$	509,787		$	416,737		$	(41,722	)	$	(884,802	)	$	461,415

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 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	$	535,041		$	473,663		$	266,621		$	85,715		$	(812,152	)	$	548,888
Adjustments to reconcile net income to net cash (used for)    provided by operating activities
Depreciation and amortization	1,504			90,247			60,637			29,345			—			181,733
Deferred income taxes	87			4,184			(359		)	3,673			—			7,585
Net changes in working capital and other	(567,137		)	(251,423		)	9,315			100,187			812,152			103,094
Net cash (used for) provided by operating activities	(30,505		)	316,671			336,214			218,920			—			841,300
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			—			—			15,782			—			15,782
Additions to property, plant and equipment	—			(148,055		)	(152,572		)	(28,609		)	—			(329,236		)
Proceeds from disposition of assets	—			—			—			17			—			17
Proceeds from disposition of equity method investment	—			27,865			—			—			—			27,865
Proceeds from sales and maturities of securities	16,056			—			—			—			—			16,056
Purchase of securities	(282,542		)	—			—			—			—			(282,542		)
Settlements of derivative instruments	—			(1,535		)	—			—			—			(1,535		)
Net cash used for investing activities	(266,486		)	(121,725		)	(152,572		)	(12,810		)	—			(553,593		)
Cash flows from financing activities
Intercompany financing	467,360			(577,898		)	102,857			7,681			—			—
Intercompany financing—OpCo	—			135,341			(135,341		)	—			—			—
Dividends paid	(67,852		)	—			—			—			—			(67,852		)
Distributions paid	—			249,999			(268,562		)	7,581			—			(10,982		)
Purchase of limited partner interests	—			—			135,341			(135,341		)	—			—
Proceeds from exercise of stock options	984			—			—			—			—			984
Proceeds from issuance of notes payable	—			—			—			19,483			—			19,483
Repayment of notes payable	—			—			—			(32,954		)	—			(32,954		)
Repurchase of common stock for treasury	(114,254		)	—			—			—			—			(114,254		)
Windfall tax benefits from share-based payment arrangements	2,452			—			—			—			—			2,452
Net cash provided by (used for) financing activities	$	288,690		$	(192,558	)	$	(165,705	)	$	(133,550	)	$	—		$	(203,123	)

	Westlake Chemical Corporation			100% Owned Guarantor Subsidiaries		OpCo (Less Than 100% Owned Guarantor Subsidiary)		Non- Guarantor Subsidiaries			Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	$	—		$	—	$	—	$	(3,260	)	$	—	$	(3,260	)
Net (decrease) increase in cash and cash equivalents	(8,301		)	2,388		17,937		69,300			—		81,324
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	$	647,646		$	5,445	$	149,482	$	159,352		$	—	$	961,925

Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2014

	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 (loss)	$	495,232		$	509,404		$	416,737		$	(1,441	)	$	(922,301	)	$	497,631
Adjustments to reconcile net income (loss) to net cash (used for)    provided by operating activities
Depreciation and amortization	1,172			82,597			58,501			7,296			—			149,566
Deferred income taxes	(418		)	26,991			8,267			(381		)	—			34,459
Net changes in working capital and other	(509,862		)	(919,521		)	1,641			599,909			922,301			94,468
Net cash (used for) provided by operating activities	(13,876		)	(300,529		)	485,146			605,383			—			776,124
Cash flows from investing activities
Acquisition of business	—			—			—			(611,087		)	—			(611,087		)
Additions to property, plant and equipment	—			(160,147		)	(144,348		)	(6,688		)	—			(311,183		)
Proceeds from disposition of assets	—			144			—			1			—			145
Proceeds from repayment of loan acquired	—			—			—			45,923			—			45,923
Proceeds from sales and maturities of securities	342,045			—			—			—			—			342,045
Purchase of securities	(117,332		)	—			—			—			—			(117,332		)
Settlements of derivative instruments	—			(556		)	(133		)	—			—			(689		)
Net cash provided by (used for) investing activities	224,713			(160,559		)	(144,481		)	(571,851		)	—			(652,178		)
Cash flows from financing activities
Intercompany financing	75,104			(143,325		)	62,221			6,000			—			—
Net distributions prior to Westlake Partners initial public offering	—			448,101			(448,101		)	—			—			—
Capitalized debt issuance costs	(1,167		)	—			—			—			—			(1,167		)
Dividends paid	(55,690		)	151,729			(151,729		)	—			—			(55,690		)
Net proceeds from issuance of Westlake Partners common units	—			—			—			286,088			—			286,088
Purchase of limited partner interests	—			—			286,088			(286,088		)	—			—
Proceeds from exercise of stock options	5,502			—			—			—			—			5,502
Repurchase of common stock for treasury	(9,495		)	—			—			—			—			(9,495		)
Windfall tax benefits from share-based payment arrangements	6,670			—			—			—			—			6,670
Net cash provided by (used for) financing activities	$	20,924		$	456,505		$	(251,521	)	$	6,000		$	—		$	231,908

	Westlake Chemical Corporation		100% Owned Guarantor Subsidiaries			OpCo (Less Than 100% Owned Guarantor Subsidiary)		Non- Guarantor Subsidiaries			Eliminations		Consolidated
Effect of exchange rate changes on cash and cash equivalents	$	—	$	—		$	—	$	(3,687	)	$	—	$	(3,687	)
Net increase (decrease) in cash and cash equivalents	231,761		(4,583		)	89,144		35,845			—		352,167
Cash and cash equivalents at beginning of period	420,948		6,227			—		34,126			—		461,301
Cash and cash equivalents at end of period	$	652,709	$	1,644		$	89,144	$	69,971		$	—	$	813,468

XML

Basis of Financial Statements (Policies)

9 Months Ended

Sep. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Financial Statements

Basis of Financial Statements

The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2014 financial statements and notes thereto of Westlake Chemical Corporation (the "Company") included in the annual report on Form 10-K for the fiscal year ended December 31, 2014 (the "2014 Form 10-K"), filed with the SEC on February 25, 2015. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Company for the fiscal year ended December 31, 2014.

In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of September 30, 2015, its results of operations for the three and nine months ended September 30, 2015 and 2014 and the changes in its cash position for the nine months ended September 30, 2015 and 2014.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2015 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Revenue from Contracts with Customers

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that will supersede the existing revenue recognition guidance. The new accounting guidance creates a framework by which an entity will allocate the transaction price to separate performance obligations and recognize revenue when each performance obligation is satisfied. Under the new standard, entities will be required to use judgment and make estimates, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price, allocating the transaction price to each separate performance obligation and determining when an entity satisfies its performance obligations. The standard allows for either "full retrospective" adoption, meaning that the standard is applied to all of the periods presented with a cumulative catch-up as of the earliest period presented, or "modified retrospective" adoption, meaning the standard is applied only to the most current period presented in the financial statements with a cumulative catch-up as of the current period. In July 2015, the FASB deferred the effective date for the revenue recognition standard. The accounting standard will now be effective for reporting periods beginning after December 15, 2017. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows.

Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items

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

Amendments to the Consolidation Analysis

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

Simplifying the Presentation of Debt Issuance Costs

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

Simplifying the Measurement of Inventory

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

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

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

Simplifying the Accounting for Measurement-Period Adjustments

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

XML

Guarantor Disclosures

9 Months Ended

Sep. 30, 2015

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. OpCo has been presented as a less than 100% owned guarantor subsidiary in each of the tables below, including for periods prior to the initial public offering of Westlake Partners. 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.

XML

Stockholders' Equity (Changes in AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance			$ (79,433)	$ (2,616)
Other comprehensive (loss) income before reclassifications			(41,318)	(33,462)
Amounts reclassified from accumulated other comprehensive loss			(1,114)	(355)
Other comprehensive loss	$ (1,941)	$ (36,301)	(42,432)	(33,817)
Accumulated other comprehensive income (loss), ending balance	(121,865)	(36,433)	(121,865)	(36,433)
Benefits Liability, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance			(23,442)	(6,696)
Other comprehensive (loss) income before reclassifications			(128)	(39)
Amounts reclassified from accumulated other comprehensive loss			1,318	422
Other comprehensive loss			1,190	383
Accumulated other comprehensive income (loss), ending balance	(22,252)	(6,313)	(22,252)	(6,313)
Cumulative Foreign Currency Exchange
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance			(56,224)	3,904
Other comprehensive (loss) income before reclassifications			(43,746)	(37,882)
Amounts reclassified from accumulated other comprehensive loss			0	0
Other comprehensive loss			(43,746)	(37,882)
Accumulated other comprehensive income (loss), ending balance	(99,970)	(33,978)	(99,970)	(33,978)
Net Unrealized Holding Gains on Investments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance			233	176
Other comprehensive (loss) income before reclassifications			2,556	4,459
Amounts reclassified from accumulated other comprehensive loss			(2,432)	(777)
Other comprehensive loss			124	3,682
Accumulated other comprehensive income (loss), ending balance	$ 357	$ 3,858	$ 357	$ 3,858

XML

Financial Instruments Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Held-to-maturity Securities
Cash Equivalents [Line Items]
Cash equivalents	$ 530,806	$ 509,811

XML

Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2015

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Investments in available-for-sale securities were classified as follows:

	September 30, 2015		December 31, 2014
Current	$	285,726	$	—
Non-current	4,098		15,414
Total available-for-sale securities	$	289,824	$	15,414

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:

	September 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Debt securities
Corporate bonds	$	194,310	$	306	$	(171	)	$	194,445
U.S. government debt	55,073		80		(2		)	55,151
Asset-backed securities	36,081		66		(17		)	36,130
Equity securities	3,804		294		—			4,098
Total available-for-sale securities	$	289,268	$	746	$	(190	)	$	289,824

	December 31, 2014
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	15,050	$	364	$	—	$	15,414
Total available-for-sale securities	$	15,050	$	364	$	—	$	15,414

Schedule of Realized Gain (Loss)

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Proceeds from sales and maturities of securities	$	1,019	$	—	$	16,056	$	342,045
Gross realized gains	—		—		3,795		1,311
Gross realized losses	—		—		—		(99		)

XML

Accounts Receivable (Tables)

9 Months Ended

Sep. 30, 2015

Accounts Receivable, Net [Abstract]

Schedule Of Accounts Receivable

Accounts receivable consist of the following:

	September 30, 2015			December 31, 2014
Trade customers	$	495,318		$	525,546
Affiliates	—			437
Allowance for doubtful accounts	(13,967		)	(13,468		)
	481,351			512,515
Federal and state taxes	19,819			8,919
Other	19,790			39,232
Accounts receivable, net	$	520,960		$	560,666

XML

Financial Instruments

9 Months Ended

Sep. 30, 2015

Investments, Debt and Equity Securities [Abstract]

Financial Instruments

Financial Instruments

Cash Equivalents

The Company had $530,806 and $509,811 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at September 30, 2015 and December 31, 2014, 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:

	September 30, 2015		December 31, 2014
Current	$	285,726	$	—
Non-current	4,098		15,414
Total available-for-sale securities	$	289,824	$	15,414

The cost, gross unrealized gains, gross unrealized losses and fair value of the Company's available-for-sale securities were as follows:

	September 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Debt securities
Corporate bonds	$	194,310	$	306	$	(171	)	$	194,445
U.S. government debt	55,073		80		(2		)	55,151
Asset-backed securities	36,081		66		(17		)	36,130
Equity securities	3,804		294		—			4,098
Total available-for-sale securities	$	289,268	$	746	$	(190	)	$	289,824

	December 31, 2014
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	15,050	$	364	$	—	$	15,414
Total available-for-sale securities	$	15,050	$	364	$	—	$	15,414

As of September 30, 2015 and December 31, 2014, net unrealized gains on the Company's available-for-sale securities of $357 and $233, respectively, net of income tax expense of $199 and $131, respectively, were recorded in accumulated other comprehensive income. See Note 13 for the fair value hierarchy of the Company's available-for-sale securities.

As of September 30, 2015, the corporate bond securities held by the Company had maturities ranging between two months to three years, the U.S. government debt securities held by the Company, excluding U.S. government agency mortgage-backed securities, had maturities ranging between four months to three years, the U.S. government agency mortgage-backed securities held by the Company had maturities ranging between five to six years and the asset-backed securities held by the Company had maturities ranging between one to 26 years.

The proceeds from sales and maturities of available-for-sale securities and the gross realized gains and losses included in the consolidated statements of operations are reflected in the table below. The cost of securities sold was determined using the specific identification method.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Proceeds from sales and maturities of securities	$	1,019	$	—	$	16,056	$	342,045
Gross realized gains	—		—		3,795		1,311
Gross realized losses	—		—		—		(99		)

XML

Inventories (Tables)

9 Months Ended

Sep. 30, 2015

Inventory Disclosure [Abstract]

Schedule Of Inventory

Inventories consist of the following:

	September 30, 2015		December 31, 2014
Finished products	$	238,671	$	300,909
Feedstock, additives and chemicals	118,498		158,635
Materials and supplies	72,837		66,232
Inventories	$	430,006	$	525,776

XML

Supplemental Information Other Income, Net (Tables)

9 Months Ended

Sep. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Other Income (Expense), Net

Other Income (Expense), Net

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Interest income	$	1,631		$	341		$	3,383		$	2,669
Dividend income	—			—			3,328			—
Foreign exchange currency (losses) gains, net	(731		)	(6,450		)	1,140			(6,695		)
Income from equity method investments	664			3,304			5,278			7,244
Impairment of equity method investment	—			—			(4,925		)	—
Gain on acquisition and related expenses, net	—			—			20,430			—
Gain from sales of equity securities	—			—			3,795			—
Other	1,072			135			1,361			1,222
Other income (expense), net	$	2,636		$	(2,670	)	$	33,790		$	4,440

XML

Long-Term Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt	$ 764,086	$ 763,997
3.60% Senior Notes Due 2022
Debt Instrument [Line Items]
Maturity	2022
Stated interest rate	3.60%
Senior notes	$ 249,197	249,108
6 1/2% Senior Notes Due 2029
Debt Instrument [Line Items]
Maturity	2029
Stated interest rate	6.50%
Senior notes	$ 100,000	100,000
6 3/4% Senior Notes Due 2032
Debt Instrument [Line Items]
Maturity	2032
Stated interest rate	6.75%
Senior notes	$ 250,000	250,000
2035 GO Zone 6 1/2% Notes
Debt Instrument [Line Items]
Maturity	2035
Stated interest rate	6.50%
Senior notes	$ 89,000	89,000
2035 IKE Zone 6 1/2% Notes
Debt Instrument [Line Items]
Maturity	2035
Stated interest rate	6.50%
Senior notes	$ 65,000	65,000
Loan related to tax-exempt waste disposal revenue bonds due 2027
Debt Instrument [Line Items]
Maturity	2027
Non-current loan payable	$ 10,889	$ 10,889

XML

Acquisition (Assets Acquired and Liabilities Assumed - Huasu) (Details) - Suzhou Huasu Plastics Company Ltd [Member] $ in Thousands	Jun. 01, 2015 USD ($)
Business Acquisition [Line Items]
Fair value of consideration transferred—cash	$ 5,518
Business Combination, Preexisting Balances Of Acquirer And Acquiree, Net	(8,538)
Fair value of the Company's investment in Huasu before the business combination	18,890
Fair value of the noncontrolling interest in Huasu	1,597
Consideration transferred, preexisting balance, fair Value of existing interest and fair value of noncontrolling interest	17,467
Cash	21,300
Working capital, excluding inventory and cash	(5,461)
Inventories	17,717
Property, plant and equipment	19,786
Other assets	7,760
Notes payable to banks	(21,085)
Total identifiable net assets	40,017
Bargain purchase gain on acquisition	$ 22,550

XML

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 961,925	$ 880,601
Marketable securities	285,726	0
Accounts receivable, net	520,960	560,666
Inventories	430,006	525,776
Prepaid expenses and other current assets	18,272	11,807
Deferred income taxes	31,541	32,437
Total current assets	2,248,430	2,011,287
Property, plant and equipment, net	2,916,630	2,757,557
Equity investments	9,593	61,305
Other assets, net
Intangible assets, net	218,652	218,431
Deferred charges and other assets, net	131,100	165,410
Total other assets, net	349,752	383,841
Total assets	5,524,405	5,213,990
Current liabilities
Accounts and notes payable	244,772	261,062
Accrued liabilities	290,115	276,118
Total current liabilities	534,887	537,180
Long-term debt	764,086	763,997
Deferred income taxes	534,824	536,066
Other liabilities	170,770	174,859
Total liabilities	$ 2,004,567	$ 2,012,102
Commitments and contingencies (Notes 8 and 19)
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 and 134,679,064 shares issued at September 30, 2015 and December 31, 2014, respectively	1,347	1,347
Common stock, held in treasury, at cost; 3,722,899 and 1,787,546 shares at September 30, 2015 and December 31, 2014, respectively	(217,542)	(96,372)
Additional paid-in capital	540,342	530,441
Retained earnings	3,022,717	2,555,528
Accumulated other comprehensive loss	(121,865)	(79,433)
Total Westlake Chemical Corporation stockholders' equity	3,224,999	2,911,511
Noncontrolling interests	294,839	290,377
Total equity	3,519,838	3,201,888
Total liabilities and equity	$ 5,524,405	$ 5,213,990

XML

Financial Instruments (Marketable Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Current	$ 285,726	$ 0
Noncurrent	4,098	15,414
Total available-for-sale securities	$ 289,824	$ 15,414

XML

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities
Net income	$ 548,888	$ 497,631
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	180,229	148,394
Recovery of doubtful accounts	778	295
Amortization of debt issuance costs	1,504	1,172
Stock-based compensation expense	7,544	6,856
Loss from disposition of fixed assets	2,590	2,635
Gain from sales of equity securities	(3,795)	0
Gain on acquisition, net of loss on the fair value remeasurement of preexisting equity interest	(21,045)	0
Impairment of equity method investment	4,925	0
Deferred income taxes	7,585	34,459
Windfall tax benefits from share-based payment arrangements	(2,452)	(6,670)
Income from equity method investments, net of dividends	(1,016)	(3,199)
Other losses (gains), net	3,584	(495)
Changes in operating assets and liabilities
Accounts receivable	54,937	6,055
Inventories	105,899	80,492
Prepaid expenses and other current assets	(5,496)	458
Accounts payable	(30,511)	(98,769)
Accrued liabilities	(10,893)	111,965
Other, net	(1,955)	(5,155)
Net cash provided by operating activities	841,300	776,124
Cash flows from investing activities
Acquisition of business, net of cash acquired	15,782	(611,087)
Additions to property, plant and equipment	(329,236)	(311,183)
Proceeds from disposition of assets	17	145
Proceeds from disposition of equity method investment	27,865	0
Proceeds from repayment of loan acquired	0	45,923
Proceeds from sales and maturities of securities	16,056	342,045
Purchase of securities	(282,542)	(117,332)
Settlements of derivative instruments	(1,535)	(689)
Net cash used for investing activities	(553,593)	(652,178)
Cash flows from financing activities
Capitalized debt issuance costs	0	(1,167)
Dividends paid	(67,852)	(55,690)
Distributions to noncontrolling interests	(10,982)	0
Net proceeds from issuance of Westlake Partners common units	0	286,088
Proceeds from exercise of stock options	984	5,502
Proceeds from issuance of notes payable	19,483	0
Repayment of notes payable	(32,954)	0
Repurchase of common stock for treasury	(114,254)	(9,495)
Windfall tax benefits from share-based payment arrangements	2,452	6,670
Net cash provided by financing activities	(203,123)	231,908
Effect of exchange rate changes on cash and cash equivalents	(3,260)	(3,687)
Net increase in cash and cash equivalents	81,324	352,167
Cash and cash equivalents at beginning of period	880,601	461,301
Cash and cash equivalents at end of period	$ 961,925	$ 813,468

XML

Pension and Post-Retirement Benefit Costs (Additional Information) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Salaried Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 0	$ 2,447
Estimated future employer contributions for next fiscal year	0
Wage Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	349	$ 916
Estimated future employer contributions for next fiscal year	$ 0

XML

Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2015

Equity [Abstract]

Schedule of Stockholders Equity

Changes in stockholders' equity for the nine months ended September 30, 2015 and 2014 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, 2014	$	1,347	$	(96,372	)	$	530,441		$	2,555,528		$	(79,433	)	$	290,377		$	3,201,888
Net income	—		—			—			535,041			—			13,847			548,888
Other comprehensive income    (loss), net of income taxes:
Pension and other post-    retirement benefits    liability	—		—			—			—			1,190			—			1,190
Foreign currency    translation adjustments	—		—			—			—			(43,746		)	—			(43,746		)
Net unrealized holding    gains on investments	—		—			—			—			124			—			124
Common stock repurchased	—		(122,249		)	—			—			—			—			(122,249		)
Shares issued—stock-    based compensation	—		1,079			(95		)	—			—			—			984
Stock-based compensation,    net of tax on stock options    exercised	—		—			9,996			—			—			—			9,996
Dividends paid	—		—			—			(67,852		)	—			—			(67,852		)
Distributions to noncontrolling    interests	—		—			—			—			—			(10,982		)	(10,982		)
Noncontrolling interest in    acquired business	—		—			—			—			—			1,597			1,597
Balances at September 30, 2015	$	1,347	$	(217,542	)	$	540,342		$	3,022,717		$	(121,865	)	$	294,839		$	3,519,838

	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, 2013	$	1,346	$	(46,220	)	$	511,432	$	1,954,661		$	(2,616	)	$	—	$	2,418,603
Net income	—		—			—		495,232			—			2,399		497,631
Other comprehensive income    (loss), net of income taxes
Pension and other post-    retirement benefits    liability	—		—			—		—			383			—		383
Foreign currency    translation adjustments	—		—			—		—			(37,882		)	—		(37,882		)
Net unrealized holding    gains on investments	—		—			—		—			3,682			—		3,682
Common stock repurchased	—		(9,495		)	—		—			—			—		(9,495		)
Shares issued—stock-    based compensation	1		2,467			3,034		—			—			—		5,502
Stock-based compensation,    net of tax on stock options    exercised	—		—			13,526		—			—			—		13,526
Dividends paid	—		—			—		(55,690		)	—			—		(55,690		)
Issuance of Westlake Chemical    Partners LP common units	—		—			—		—			—			286,088		286,088
Balances at September 30, 2014	$	1,347	$	(53,248	)	$	527,992	$	2,394,203		$	(36,433	)	$	288,487	$	3,122,348

Schedule of Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive income (loss) by component for the nine months ended September 30, 2015 and 2014 were as follows:

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2014	$	(23,442	)	$	(56,224	)	$	233		$	(79,433	)
Other comprehensive (loss) income before    reclassifications	(128		)	(43,746		)	2,556			(41,318		)
Amounts reclassified from accumulated other    comprehensive loss (income)	1,318			—			(2,432		)	(1,114		)
Net other comprehensive income (loss) for the period	1,190			(43,746		)	124			(42,432		)
Balances at September 30, 2015	$	(22,252	)	$	(99,970	)	$	357		$	(121,865	)

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2013	$	(6,696	)	$	3,904		$	176		$	(2,616	)
Other comprehensive (loss) income before    reclassifications	(39		)	(37,882		)	4,459			(33,462		)
Amounts reclassified from accumulated other    comprehensive loss (income)	422			—			(777		)	(355		)
Net other comprehensive income (loss) for the period	383			(37,882		)	3,682			(33,817		)
Balances at September 30, 2014	$	(6,313	)	$	(33,978	)	$	3,858		$	(36,433	)

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 and nine months ended September 30, 2015 and 2014:

Details about Accumulated    Other Comprehensive    Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Three Months Ended September 30,						Nine Months Ended September 30,
		2015			2014			2015			2014
Amortization of pension and    other post-retirement items
Prior service costs	(1)	$	—		$	(87	)	$	—		$	(261	)
Net loss	(1)	(692		)	(153		)	(2,019		)	(424		)
		(692		)	(240		)	(2,019		)	(685		)
	Provision for income    taxes	241			92			701			263
		(451		)	(148		)	(1,318		)	(422		)
Net unrealized gains on    available-for-sale    investments
Realized gain on    available-for-sale    investments	Other income    (expense), net	—			—			3,795			1,212
	Provision for income    taxes	—			—			(1,363		)	(435		)
		—			—			2,432			777
Total reclassifications for    the period		$	(451	)	$	(148	)	$	1,114		$	355

_____________

(1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 10 (Employee Benefits) to the financial statements included in the 2014 Form 10-K.

XML

Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
3.60% Senior Notes Due 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity	2022
Stated interest rate	3.60%
3.60% Senior Notes Due 2022 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 249,197	$ 249,108
3.60% Senior Notes Due 2022 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 246,843	248,630
6 1/2% Senior Notes Due 2029
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity	2029
Stated interest rate	6.50%
6 1/2% Senior Notes Due 2029 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 100,000	100,000
6 1/2% Senior Notes Due 2029 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 116,663	116,384
6 3/4% Senior Notes Due 2032
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity	2032
Stated interest rate	6.75%
6 3/4% Senior Notes Due 2032 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 250,000	250,000
6 3/4% Senior Notes Due 2032 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 273,655	285,545
2035 GO Zone 6 1/2% Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity	2035
Stated interest rate	6.50%
2035 GO Zone 6 1/2% Notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 89,000	89,000
2035 GO Zone 6 1/2% Notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 103,740	106,504
2035 IKE Zone 6 1/2% Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity	2035
Stated interest rate	6.50%
2035 IKE Zone 6 1/2% Notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 65,000	65,000
2035 IKE Zone 6 1/2% Notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 74,719	77,784
Loan related to tax-exempt waste disposal revenue bonds due 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity	2027
Loan related to tax-exempt waste disposal revenue bonds due 2027 | Carrying Value
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
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 10,889	$ 10,889

XML

Supplemental Information

9 Months Ended

Sep. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Supplemental Information

Supplemental Information

Accrued Liabilities

Accrued liabilities were $290,115 and $276,118 at September 30, 2015 and December 31, 2014, respectively. Accrued rebates and accrued incentive compensation, which are components of accrued liabilities, were $39,046 and $43,151 at September 30, 2015, respectively, and $49,900 and $37,626 at December 31, 2014, respectively. No other component of accrued liabilities was more than five percent of total current liabilities.

Other Liabilities

Other liabilities were $170,770 and $174,859 at September 30, 2015 and December 31, 2014, respectively. Non-current pension obligation, which is a component of other liabilities, was $127,235 and $136,296 at September 30, 2015 and December 31, 2014, respectively. No other component of other liabilities was more than five percent of total liabilities.

Other Income (Expense), Net

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Interest income	$	1,631		$	341		$	3,383		$	2,669
Dividend income	—			—			3,328			—
Foreign exchange currency (losses) gains, net	(731		)	(6,450		)	1,140			(6,695		)
Income from equity method investments	664			3,304			5,278			7,244
Impairment of equity method investment	—			—			(4,925		)	—
Gain on acquisition and related expenses, net	—			—			20,430			—
Gain from sales of equity securities	—			—			3,795			—
Other	1,072			135			1,361			1,222
Other income (expense), net	$	2,636		$	(2,670	)	$	33,790		$	4,440

XML

Pension and Post-Retirement Benefit Costs (Tables)

9 Months Ended

Sep. 30, 2015

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 September 30,										Nine Months Ended September 30,
	2015					2014					2015					2014
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Service cost	$	—		$	416	$	83		$	248	$	29		$	1,248	$	250		$	248
Interest cost	487			528		576			562		1,519			1,585		1,747			562
Expected return on plan assets	(712		)	—		(777		)	—		(2,237		)	—		(2,363		)	—
Amortization of prior    service cost	—			—		74			—		—			—		223			—
Amortization of net loss	333			263		71			—		942			789		204			—
Net periodic benefit cost	$	108		$	1,207	$	27		$	810	$	253		$	3,622	$	61		$	810

Components of net periodic benefit cost for the Company's other post-retirement benefits are as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
	U.S. Plans		U.S. Plans		U.S. Plans		U.S. Plans
Service cost	$	6	$	6	$	17	$	16
Interest cost	149		185		448		548
Amortization of prior service cost	—		13		—		38
Amortization of net loss	96		82		288		220
Net periodic benefit cost	$	251	$	286	$	753	$	822

XML

Insurance Recovery

9 Months Ended

Sep. 30, 2015

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. For the three and nine months ended September 30, 2015, the Company recognized approximately $3,347 and $7,809, respectively, as a partial insurance recovery related to business interruption costs, primarily for additional costs incurred to procure the necessary feedstock and other costs as a result of the fire at the third-party facility. The partial insurance recovery is included in cost of sales in the consolidated statements of operations.

XML

Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 183,604	$ 167,757	$ 535,041	$ 495,232
Less: Net income attributable to participating securities	(195)	(353)	(653)	(1,099)
Net income attributable to common shareholders	$ 183,409	$ 167,404	$ 534,388	$ 494,133

XML

Basis of Financial Statements

9 Months Ended

Sep. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Financial Statements

Basis of Financial Statements

The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2014 financial statements and notes thereto of Westlake Chemical Corporation (the "Company") included in the annual report on Form 10-K for the fiscal year ended December 31, 2014 (the "2014 Form 10-K"), filed with the SEC on February 25, 2015. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Company for the fiscal year ended December 31, 2014.

In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of September 30, 2015, its results of operations for the three and nine months ended September 30, 2015 and 2014 and the changes in its cash position for the nine months ended September 30, 2015 and 2014.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2015 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Recent Accounting Pronouncements

Revenue from Contracts with Customers

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that will supersede the existing revenue recognition guidance. The new accounting guidance creates a framework by which an entity will allocate the transaction price to separate performance obligations and recognize revenue when each performance obligation is satisfied. Under the new standard, entities will be required to use judgment and make estimates, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price, allocating the transaction price to each separate performance obligation and determining when an entity satisfies its performance obligations. The standard allows for either "full retrospective" adoption, meaning that the standard is applied to all of the periods presented with a cumulative catch-up as of the earliest period presented, or "modified retrospective" adoption, meaning the standard is applied only to the most current period presented in the financial statements with a cumulative catch-up as of the current period. In July 2015, the FASB deferred the effective date for the revenue recognition standard. The accounting standard will now be effective for reporting periods beginning after December 15, 2017. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows.

Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items

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

Amendments to the Consolidation Analysis

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

Simplifying the Presentation of Debt Issuance Costs

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

Simplifying the Measurement of Inventory

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

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

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

Simplifying the Accounting for Measurement-Period Adjustments

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

XML

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2015	Dec. 31, 2014
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	134,679,064
Common stock, held in treasury	3,722,899	1,787,546

XML

Stock-Based Compensation

9 Months Ended

Sep. 30, 2015

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 $2,639 and $2,346 for the three months ended September 30, 2015 and 2014,respectively, and $7,544 and $6,856 for the nine months ended September 30, 2015 and 2014, respectively.

XML

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 28, 2015
Document Documentand Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Trading Symbol	WLK
Entity Registrant Name	WESTLAKE CHEMICAL CORP
Entity Central Index Key	0001262823
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		130,652,184

XML

Derivative Instruments

9 Months Ended

Sep. 30, 2015

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.

For derivative instruments that are designated and qualify as fair value hedges, the gains or losses on the derivative instruments, as well as the offsetting losses or gains on the hedged items attributable to the hedged risk, are included in cost of sales in the consolidated statement of operations. The Company had no derivative instruments that were designated as fair value hedges for the nine months ended September 30, 2015 and 2014.

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 and nine months ended September 30, 2015 and 2014.

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).

Disclosures related to the Company's derivative assets and derivative liabilities subject to enforceable master netting arrangements have not been presented as they are not material to the Company's consolidated balance sheets at September 30, 2015 and December 31, 2014.

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
		September 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	2,722	$	3,145
Commodity forward contracts	Deferred charges and    other assets, net	2,017		—
Total derivative assets		$	4,739	$	3,145

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		September 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	5,421	$	6,549
Commodity forward contracts	Other liabilities	9,846		3,559
Total derivative liabilities		$	15,267	$	10,108

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 September 30,						Nine Months Ended September 30,
		2015			2014			2015			2014
Commodity forward contracts	Gross profit	$	(9,314	)	$	(6,937	)	$	(4,478	)	$	(7,308	)

See Note 13 for the fair value of the Company's derivative instruments.

XML

Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 961,925	$ 880,601	$ 813,468	$ 461,301
Marketable securities	285,726	0
Accounts receivable, net	520,960	560,666
Inventories	430,006	525,776
Prepaid expenses and other current assets	18,272	11,807
Deferred income taxes	31,541	32,437
Total current assets	2,248,430	2,011,287
Property, plant and equipment, net	2,916,630	2,757,557
Equity investments	9,593	61,305
Other assets, net	349,752	383,841
Total assets	5,524,405	5,213,990
Accounts payable		261,062
Accounts and notes payable	244,772	261,062
Accrued liabilities	290,115	276,118
Total current liabilities	534,887	537,180
Long-term debt	764,086	763,997
Deferred income taxes	534,824	536,066
Other liabilities	170,770	174,859
Total liabilities	2,004,567	2,012,102
Total Westlake Chemical Corporation stockholders' equity	3,224,999	2,911,511
Noncontrolling interests	294,839	290,377
Total equity	3,519,838	3,201,888	3,122,348	2,418,603
Total liabilities and equity	5,524,405	5,213,990
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	647,646	655,947	652,709	420,948
Marketable securities	285,726
Accounts receivable, net	9,371	8,451
Inventories	0	0
Prepaid expenses and other current assets	1,355	172
Deferred income taxes	441	409
Total current assets	944,539	664,979
Property, plant and equipment, net	0	0
Equity investments	4,879,268	4,033,378
Other assets, net	17,541	30,543
Total assets	5,841,348	4,728,900
Accounts payable		1,055,527
Accounts and notes payable	1,847,047
Accrued liabilities	16,105	8,754
Total current liabilities	1,863,152	1,064,281
Long-term debt	753,197	753,108
Deferred income taxes	0	0
Other liabilities	0	0
Total liabilities	2,616,349	1,817,389
Total Westlake Chemical Corporation stockholders' equity	3,224,999	2,911,511
Noncontrolling interests	0	0
Total equity	3,224,999	2,911,511
Total liabilities and equity	5,841,348	4,728,900
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	5,445	3,057	1,644	6,227
Marketable securities	0
Accounts receivable, net	2,165,248	1,454,709
Inventories	333,553	414,975
Prepaid expenses and other current assets	15,244	9,485
Deferred income taxes	30,529	29,832
Total current assets	2,550,019	1,912,058
Property, plant and equipment, net	1,533,456	1,477,515
Equity investments	1,204,734	1,237,080
Other assets, net	353,506	387,325
Total assets	5,641,715	5,013,978
Accounts payable		160,834
Accounts and notes payable	131,438
Accrued liabilities	168,569	203,608
Total current liabilities	300,007	364,442
Long-term debt	10,889	10,889
Deferred income taxes	503,102	497,919
Other liabilities	49,174	43,452
Total liabilities	863,172	916,702
Total Westlake Chemical Corporation stockholders' equity	4,778,543	4,097,276
Noncontrolling interests	0	0
Total equity	4,778,543	4,097,276
Total liabilities and equity	5,641,715	5,013,978
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	149,482	131,545	89,144	0
Marketable securities	0
Accounts receivable, net	58,514	56,049
Inventories	3,272	6,634
Prepaid expenses and other current assets	382	212
Deferred income taxes	0	0
Total current assets	211,650	194,440
Property, plant and equipment, net	962,221	842,057
Equity investments	0	0
Other assets, net	46,542	57,733
Total assets	1,220,413	1,094,230
Accounts payable		17,680
Accounts and notes payable	33,476
Accrued liabilities	21,055	11,225
Total current liabilities	54,531	28,905
Long-term debt	195,154	227,638
Deferred income taxes	1,489	1,848
Other liabilities	0	0
Total liabilities	251,174	258,391
Total Westlake Chemical Corporation stockholders' equity	969,239	835,839
Noncontrolling interests	0	0
Total equity	969,239	835,839
Total liabilities and equity	1,220,413	1,094,230
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	159,352	90,052	69,971	34,126
Marketable securities	0
Accounts receivable, net	135,837	135,133
Inventories	93,181	104,167
Prepaid expenses and other current assets	3,576	1,938
Deferred income taxes	647	2,196
Total current assets	392,593	333,486
Property, plant and equipment, net	420,953	437,985
Equity investments	468,760	352,550
Other assets, net	133,196	141,948
Total assets	1,415,502	1,265,969
Accounts payable		95,856
Accounts and notes payable	80,685
Accrued liabilities	86,883	77,372
Total current liabilities	167,568	173,228
Long-term debt	0	0
Deferred income taxes	36,112	42,369
Other liabilities	121,596	131,407
Total liabilities	325,276	347,004
Total Westlake Chemical Corporation stockholders' equity	795,387	628,588
Noncontrolling interests	294,839	290,377
Total equity	1,090,226	918,965
Total liabilities and equity	1,415,502	1,265,969
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	$ 0	$ 0
Marketable securities	0
Accounts receivable, net	(1,848,010)	(1,093,676)
Inventories	0	0
Prepaid expenses and other current assets	(2,285)	0
Deferred income taxes	(76)	0
Total current assets	(1,850,371)	(1,093,676)
Property, plant and equipment, net	0	0
Equity investments	(6,543,169)	(5,561,703)
Other assets, net	(201,033)	(233,708)
Total assets	(8,594,573)	(6,889,087)
Accounts payable		(1,068,835)
Accounts and notes payable	(1,847,874)
Accrued liabilities	(2,497)	(24,841)
Total current liabilities	(1,850,371)	(1,093,676)
Long-term debt	(195,154)	(227,638)
Deferred income taxes	(5,879)	(6,070)
Other liabilities	0	0
Total liabilities	(2,051,404)	(1,327,384)
Total Westlake Chemical Corporation stockholders' equity	(6,543,169)	(5,561,703)
Noncontrolling interests	0	0
Total equity	(6,543,169)	(5,561,703)
Total liabilities and equity	$ (8,594,573)	$ (6,889,087)

XML

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Net sales	$ 1,188,037	$ 1,253,227	$ 3,476,570	$ 3,279,479
Cost of sales	876,761	891,707	2,527,567	2,324,978
Gross profit	311,276	361,520	949,003	954,501
Selling, general and administrative expenses	57,248	54,759	170,321	132,897
Income from operations	254,028	306,761	778,682	821,604
Other income (expense)
Interest expense	(8,211)	(9,486)	(26,760)	(28,182)
Other income, net	2,636	(2,670)	33,790	4,440
Income before income taxes	248,453	294,605	785,712	797,862
Provision for income taxes	60,033	124,449	236,824	300,231
Net income	188,420	170,156	548,888	497,631
Net income attributable to noncontrolling interests	4,816	2,399	13,847	2,399
Net income attributable to Westlake Chemical Corporation	$ 183,604	$ 167,757	$ 535,041	$ 495,232
Earnings per common share attributable to Westlake Chemical Corporation
Basic (usd per share)	$ 1.39	$ 1.26	$ 4.04	$ 3.71
Diluted (usd per share)	$ 1.39	$ 1.25	$ 4.02	$ 3.69
Weighted average shares outstanding:
Basic	131,664,296	133,299,458	132,301,814	133,199,304
Diluted	132,121,235	133,846,059	132,786,534	133,743,145
Dividends per common share	$ 0.1815	$ 0.1650	$ 0.5115	$ 0.4170

XML

Other Assets

9 Months Ended

Sep. 30, 2015

Other Assets [Abstract]

Other Assets

Other Assets

Amortization expense on intangible and other assets of $9,542 and $9,283 is included in the consolidated statements of operations for the three months ended September 30, 2015 and 2014, respectively. Amortization expense on intangible and other assets of $28,604 and $26,566 is included in the consolidated statements of operations for the nine months ended September 30, 2015 and 2014, respectively.

Goodwill

Goodwill for the Olefins segment was $29,990 at September 30, 2015 and December 31, 2014. Goodwill for the Vinyls segment was $32,026 at September 30, 2015 and December 31, 2014. There were no changes in the carrying amount of goodwill by operating segments for the nine months ended September 30, 2015.

XML

Property, Plant and Equipment

9 Months Ended

Sep. 30, 2015

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

As of September 30, 2015, the Company had property, plant and equipment, net totaling $2,916,630. 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 $52,208 and $45,080 is included in cost of sales in the consolidated statements of operations for the three months ended September 30, 2015 and 2014, respectively. Depreciation expense on property, plant and equipment of $153,129 and $123,000 is included in cost of sales in the consolidated statements of operations for the nine months ended September 30, 2015 and 2014, respectively.

XML

Acquisition

9 Months Ended

Sep. 30, 2015

Business Combinations [Abstract]

Acquisitions

Acquisition

On June 1, 2015, the Company acquired an additional 35.7% equity interest in Suzhou Huasu Plastics Co., Ltd. ("Huasu") from INEOS Chlor Vinyls Holdings B.V., increasing its interest in Huasu to 95.0%. Huasu is a polyvinyl chloride ("PVC") joint venture based near Shanghai, People's Republic of China and has a combined annual capacity of 300 million pounds of PVC resin, 145 million pounds of PVC film and sheet and 33 million pounds of building products.

Prior to the acquisition of this 35.7% interest, the Company owned a 59.3% interest in Huasu. The Company accounted for the investment using the equity method of accounting because Huasu did not meet the definition of a variable interest entity and because contractual arrangements giving certain substantive participatory rights to minority shareholders prevented the Company from exercising a controlling financial interest over Huasu. As a result of the Company obtaining control over Huasu, the Company's 59.3% interest was remeasured to fair value, resulting in a loss of $1,505, which is included in other income (expense), net in the consolidated statements of operations.

The closing date purchase price of $5,518 was paid with available cash on hand. The acquisition is being accounted for under the acquisition method of accounting. The transaction resulted in a bargain purchase acquisition-date gain of $22,550 and is recognized in other income (expense), net in the consolidated statements of operations. The Company believes there are several factors that contributed to this transaction resulting in a bargain purchase acquisition-date gain, including the slowdown in the growth of, and current weakness in, the Chinese economy. The assets acquired and liabilities assumed and the results of operations of this acquired business are included in the Vinyls segment. Huasu's net sales and earnings included in the consolidated statements of operations since the acquisition date have not been presented separately as they are not material to the Company's consolidated statements of operations for the three and nine months ended September 30, 2015. The acquisition-related costs recognized in the consolidated statements of operations for the three and nine months ended September 30, 2015 are not material. The pro forma impact of this business combination has not been presented as it is not material to the Company's consolidated statements of operations for the nine months ended September 30, 2015 and 2014.

The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition. The final determination of fair value for certain assets and liabilities will be completed as soon as the information necessary to complete the analysis is obtained. These amounts will be finalized as soon as possible, but no later than one year from the acquisition date.

Fair value of consideration transferred—cash	$	5,518
Preexisting balances between the Company and Huasu, net	(8,538		)
Fair value of the Company's investment in Huasu before the business combination (1)	18,890
Fair value of the noncontrolling interest in Huasu (1)	1,597
	$	17,467
Preliminary allocation of consideration transferred to net assets acquired:
Cash	$	21,300
Working capital, excluding inventory and cash (2)	(5,461		)
Inventories	17,717
Property, plant and equipment	19,786
Other assets	7,760
Notes payable to banks	(21,085		)
Total identifiable net assets	40,017
Bargain purchase gain on acquisition	$	22,550

_____________

(1) The fair values of the Company's 59.3% equity interest and the noncontrolling interest were estimated using internally developed, unobservable inputs (Level 3 inputs in the fair value hierarchy of fair value accounting) based on a cost approach.

(2) The fair value of accounts receivable acquired is $2,515, with the gross contractual amount being $3,006. The Company expects $491 to be uncollectible.

XML

Fair Value Measurements

9 Months Ended

Sep. 30, 2015

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:

	September 30, 2015
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	4,700		$	39		$	4,739
Risk management liabilities—Commodity forward contracts	(8,395		)	(6,872		)	(15,267		)
Marketable securities
Available-for-sale securities	57,733			232,091			289,824
	December 31, 2014
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	3,143		$	2		$	3,145
Risk management liabilities—Commodity forward contracts	—			(10,108		)	(10,108		)
Marketable securities
Available-for-sale securities	15,414			—			15,414

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 nine months ended September 30, 2015 and 2014.

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.

	September 30, 2015				December 31, 2014
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	249,197	$	246,843	$	249,108	$	248,630
6 ½% senior notes due 2029	100,000		116,663		100,000		116,384
6 ¾% senior notes due 2032	250,000		273,655		250,000		285,545
6 ½% GO Zone Senior Notes Due 2035	89,000		103,740		89,000		106,504
6 ½% IKE Zone Senior Notes Due 2035	65,000		74,719		65,000		77,784
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

XML

Stockholders Equity

9 Months Ended

Sep. 30, 2015

Equity [Abstract]

Stockholders' Equity

Stockholders' Equity

Changes in stockholders' equity for the nine months ended September 30, 2015 and 2014 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, 2014	$	1,347	$	(96,372	)	$	530,441		$	2,555,528		$	(79,433	)	$	290,377		$	3,201,888
Net income	—		—			—			535,041			—			13,847			548,888
Other comprehensive income    (loss), net of income taxes:
Pension and other post-    retirement benefits    liability	—		—			—			—			1,190			—			1,190
Foreign currency    translation adjustments	—		—			—			—			(43,746		)	—			(43,746		)
Net unrealized holding    gains on investments	—		—			—			—			124			—			124
Common stock repurchased	—		(122,249		)	—			—			—			—			(122,249		)
Shares issued—stock-    based compensation	—		1,079			(95		)	—			—			—			984
Stock-based compensation,    net of tax on stock options    exercised	—		—			9,996			—			—			—			9,996
Dividends paid	—		—			—			(67,852		)	—			—			(67,852		)
Distributions to noncontrolling    interests	—		—			—			—			—			(10,982		)	(10,982		)
Noncontrolling interest in    acquired business	—		—			—			—			—			1,597			1,597
Balances at September 30, 2015	$	1,347	$	(217,542	)	$	540,342		$	3,022,717		$	(121,865	)	$	294,839		$	3,519,838

	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, 2013	$	1,346	$	(46,220	)	$	511,432	$	1,954,661		$	(2,616	)	$	—	$	2,418,603
Net income	—		—			—		495,232			—			2,399		497,631
Other comprehensive income    (loss), net of income taxes
Pension and other post-    retirement benefits    liability	—		—			—		—			383			—		383
Foreign currency    translation adjustments	—		—			—		—			(37,882		)	—		(37,882		)
Net unrealized holding    gains on investments	—		—			—		—			3,682			—		3,682
Common stock repurchased	—		(9,495		)	—		—			—			—		(9,495		)
Shares issued—stock-    based compensation	1		2,467			3,034		—			—			—		5,502
Stock-based compensation,    net of tax on stock options    exercised	—		—			13,526		—			—			—		13,526
Dividends paid	—		—			—		(55,690		)	—			—		(55,690		)
Issuance of Westlake Chemical    Partners LP common units	—		—			—		—			—			286,088		286,088
Balances at September 30, 2014	$	1,347	$	(53,248	)	$	527,992	$	2,394,203		$	(36,433	)	$	288,487	$	3,122,348

Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive income (loss) by component for the nine months ended September 30, 2015 and 2014 were as follows:

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2014	$	(23,442	)	$	(56,224	)	$	233		$	(79,433	)
Other comprehensive (loss) income before    reclassifications	(128		)	(43,746		)	2,556			(41,318		)
Amounts reclassified from accumulated other    comprehensive loss (income)	1,318			—			(2,432		)	(1,114		)
Net other comprehensive income (loss) for the period	1,190			(43,746		)	124			(42,432		)
Balances at September 30, 2015	$	(22,252	)	$	(99,970	)	$	357		$	(121,865	)

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Net Unrealized Holding Gains on Investments, Net of Tax			Total
Balances at December 31, 2013	$	(6,696	)	$	3,904		$	176		$	(2,616	)
Other comprehensive (loss) income before    reclassifications	(39		)	(37,882		)	4,459			(33,462		)
Amounts reclassified from accumulated other    comprehensive loss (income)	422			—			(777		)	(355		)
Net other comprehensive income (loss) for the period	383			(37,882		)	3,682			(33,817		)
Balances at September 30, 2014	$	(6,313	)	$	(33,978	)	$	3,858		$	(36,433	)

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 and nine months ended September 30, 2015 and 2014:

Details about Accumulated    Other Comprehensive    Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Three Months Ended September 30,						Nine Months Ended September 30,
		2015			2014			2015			2014
Amortization of pension and    other post-retirement items
Prior service costs	(1)	$	—		$	(87	)	$	—		$	(261	)
Net loss	(1)	(692		)	(153		)	(2,019		)	(424		)
		(692		)	(240		)	(2,019		)	(685		)
	Provision for income    taxes	241			92			701			263
		(451		)	(148		)	(1,318		)	(422		)
Net unrealized gains on    available-for-sale    investments
Realized gain on    available-for-sale    investments	Other income    (expense), net	—			—			3,795			1,212
	Provision for income    taxes	—			—			(1,363		)	(435		)
		—			—			2,432			777
Total reclassifications for    the period		$	(451	)	$	(148	)	$	1,114		$	355

_____________

(1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 10 (Employee Benefits) to the financial statements included in the 2014 Form 10-K.

XML

Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	$ 2,639	$ 2,346	$ 7,544	$ 6,856

XML

Accounts and Notes Payable

9 Months Ended

Sep. 30, 2015

Accounts and Notes Payable [Abstract]

Accounts and Notes Payable

Accounts and Notes Payable

Accounts and notes payable consist of the following:

	September 30, 2015		December 31, 2014
Accounts payable	$	237,622	$	261,062
Notes payable to banks	7,150		—
Accounts and notes payable	$	244,772	$	261,062

XML

Long-Term Debt

9 Months Ended

Sep. 30, 2015

Debt Disclosure [Abstract]

Long-Term Debt

Long-Term Debt

Long-term debt consists of the following:

	September 30, 2015		December 31, 2014
3.60% senior notes due 2022	$	249,197	$	249,108
6 ½% senior notes due 2029	100,000		100,000
6 ¾% senior notes due 2032	250,000		250,000
6 ½% senior notes due 2035 (the "6 ½% GO Zone Senior Notes Due 2035")	89,000		89,000
6 ½% senior notes due 2035 (the "6 ½% IKE Zone Senior Notes Due 2035")	65,000		65,000
Loan related to tax-exempt waste disposal revenue bonds due 2027	10,889		10,889
Long-term debt, net	$	764,086	$	763,997

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 September 30, 2015, 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 September 30, 2015, the Company had outstanding letters of credit totaling $29,953 and borrowing availability of $346,374 under the revolving credit facility.

XML

Pension and Post-Retirement Benefit Costs

9 Months Ended

Sep. 30, 2015

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 September 30,										Nine Months Ended September 30,
	2015					2014					2015					2014
	U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans		U.S. Plans			Non-U.S. Plans
Service cost	$	—		$	416	$	83		$	248	$	29		$	1,248	$	250		$	248
Interest cost	487			528		576			562		1,519			1,585		1,747			562
Expected return on plan assets	(712		)	—		(777		)	—		(2,237		)	—		(2,363		)	—
Amortization of prior    service cost	—			—		74			—		—			—		223			—
Amortization of net loss	333			263		71			—		942			789		204			—
Net periodic benefit cost	$	108		$	1,207	$	27		$	810	$	253		$	3,622	$	61		$	810

The Company made no contribution to the U.S. salaried pension plan in the first nine months of 2015. The Company contributed $2,447 to the U.S. salaried pension plan in the first nine months of 2014. The Company contributed $349 and $916 to the U.S. wage pension plan in the first nine months of 2015 and 2014, respectively. 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 no contribution for the salaried pension plan and no further contribution to the wage pension plan for the fiscal year ending December 31, 2015.

Other Post-retirement Benefits

Components of net periodic benefit cost for the Company's other post-retirement benefits are as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
	U.S. Plans		U.S. Plans		U.S. Plans		U.S. Plans
Service cost	$	6	$	6	$	17	$	16
Interest cost	149		185		448		548
Amortization of prior service cost	—		13		—		38
Amortization of net loss	96		82		288		220
Net periodic benefit cost	$	251	$	286	$	753	$	822

XML

Fair Value Measurements (Summary of Assets and Liabilities Accounted at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 289,824	$ 15,414
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	289,824	15,414
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	57,733	15,414
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	232,091	0
Recurring | Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	4,739	3,145
Risk management liabilities - Commodity forward contracts	(15,267)	(10,108)
Recurring | Forward Contracts [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	4,700	3,143
Risk management liabilities - Commodity forward contracts	(8,395)	0
Recurring | Forward Contracts [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	39	2
Risk management liabilities - Commodity forward contracts	$ (6,872)	$ (10,108)

XML

Income Taxes (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate	24.20%	42.20%	30.10%	37.60%
U.S. federal statutory income tax rate			35.00%	35.00%
Anticipated reductions to unrecognized tax benefits within next twelve months	$ 0		$ 0
Income Tax Examination, Penalties and Interest Accrued	$ 0		$ 0

XML

Derivative Instruments (Impact of Derivative Instruments on Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivatives Not Designated As Hedging Instruments | Forward Contracts [Member] | Cost of Sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	$ (9,314)	$ (6,937)	$ (4,478)	$ (7,308)

XML

Long-Term Debt (Tables)

9 Months Ended

Sep. 30, 2015

Debt Disclosure [Abstract]

Schedule Of Long-Term Debt

Long-term debt consists of the following:

	September 30, 2015		December 31, 2014
3.60% senior notes due 2022	$	249,197	$	249,108
6 ½% senior notes due 2029	100,000		100,000
6 ¾% senior notes due 2032	250,000		250,000
6 ½% senior notes due 2035 (the "6 ½% GO Zone Senior Notes Due 2035")	89,000		89,000
6 ½% senior notes due 2035 (the "6 ½% IKE Zone Senior Notes Due 2035")	65,000		65,000
Loan related to tax-exempt waste disposal revenue bonds due 2027	10,889		10,889
Long-term debt, net	$	764,086	$	763,997

XML

Other Assets (Additional Information) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Other Assets [Line Items]
Amortization expense on intangible assets, included in other assets	$ 9,542	$ 9,283	$ 28,604	$ 26,566
Olefins
Other Assets [Line Items]
Goodwill	29,990		29,990		$ 29,990
Vinyls
Other Assets [Line Items]
Goodwill	$ 32,026		$ 32,026		$ 32,026

XML

Earnings per Share

9 Months Ended

Sep. 30, 2015

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 September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Net income attributable to    Westlake Chemical Corporation	$	183,604		$	167,757		$	535,041		$	495,232
Less:
Net income attributable to participating securities	(195		)	(353		)	(653		)	(1,099		)
Net income attributable to common shareholders	$	183,409		$	167,404		$	534,388		$	494,133

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 September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Weighted average common shares—basic	131,664,296		133,299,458		132,301,814		133,199,304
Plus incremental shares from:
Assumed exercise of options	456,939		546,601		484,720		543,841
Weighted average common shares—diluted	132,121,235		133,846,059		132,786,534		133,743,145
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.39	$	1.26	$	4.04	$	3.71
Diluted	$	1.39	$	1.25	$	4.02	$	3.69

Excluded from the computation of diluted earnings per share are options to purchase 315,285 and 295,825 shares of common stock for the three and nine months ended September 30, 2015, respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive. There were no options excluded from the computation of diluted earnings per share for the three and nine months ended September 30, 2014.

XML

Segment Information

9 Months Ended

Sep. 30, 2015

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 September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Net external sales
Olefins
Polyethylene	$	423,631		$	498,450		$	1,283,545		$	1,461,097
Styrene, feedstock and other	164,466			204,647			508,507			663,851
Total Olefins	588,097			703,097			1,792,052			2,124,948
Vinyls
PVC, caustic soda and other	468,235			416,771			1,315,101			776,060
Building products	131,705			133,359			369,417			378,471
Total Vinyls	599,940			550,130			1,684,518			1,154,531
	$	1,188,037		$	1,253,227		$	3,476,570		$	3,279,479
Intersegment sales
Olefins	$	28,551		$	26,518		$	78,654		$	118,153
Vinyls	341			355			1,098			1,029
	$	28,892		$	26,873		$	79,752		$	119,182
Income (loss) from operations
Olefins	$	196,703		$	259,277		$	608,744		$	770,267
Vinyls	67,779			59,445			202,831			76,460
Corporate and other	(10,454		)	(11,961		)	(32,893		)	(25,123		)
	$	254,028		$	306,761		$	778,682		$	821,604
Depreciation and amortization
Olefins	$	27,678		$	26,443		$	82,240		$	79,811
Vinyls	33,432			27,336			97,615			68,127
Corporate and other	138			141			374			456
	$	61,248		$	53,920		$	180,229		$	148,394
Other income (expense), net
Olefins	$	1,323		$	1,609		$	3,770		$	4,262
Vinyls	10			1,189			6,927			942
Corporate and other	1,303			(5,468		)	23,093			(764		)
	$	2,636		$	(2,670	)	$	33,790		$	4,440
Provision for (benefit from) income taxes
Olefins	$	45,865		$	105,030		$	186,534		$	282,082
Vinyls	15,812			21,761			55,270			22,121
Corporate and other	(1,644		)	(2,342		)	(4,980		)	(3,972		)
	$	60,033		$	124,449		$	236,824		$	300,231
Capital expenditures
Olefins	$	69,885		$	48,519		$	206,719		$	121,041
Vinyls	53,510			44,067			114,935			187,449
Corporate and other	1,909			1,685			7,582			2,693
	$	125,304		$	94,271		$	329,236		$	311,183

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Income from operations	$	254,028		$	306,761		$	778,682		$	821,604
Interest expense	(8,211		)	(9,486		)	(26,760		)	(28,182		)
Other income (expense), net	2,636			(2,670		)	33,790			4,440
Income before income taxes	$	248,453		$	294,605		$	785,712		$	797,862

	September 30, 2015		December 31, 2014
Total assets
Olefins	$	1,817,303	$	1,785,895
Vinyls	2,601,263		2,618,646
Corporate and other	1,105,839		809,449
	$	5,524,405	$	5,213,990

XML

Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished products	$ 238,671	$ 300,909
Feedstock, additives and chemicals	118,498	158,635
Materials and supplies	72,837	66,232
Inventories	$ 430,006	$ 525,776

XML

Acquisition (Tables)

9 Months Ended

Sep. 30, 2015

Suzhou Huasu Plastics Company Ltd [Member]

Business Acquisition [Line Items]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]

The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition. The final determination of fair value for certain assets and liabilities will be completed as soon as the information necessary to complete the analysis is obtained. These amounts will be finalized as soon as possible, but no later than one year from the acquisition date.

Fair value of consideration transferred—cash	$	5,518
Preexisting balances between the Company and Huasu, net	(8,538		)
Fair value of the Company's investment in Huasu before the business combination (1)	18,890
Fair value of the noncontrolling interest in Huasu (1)	1,597
	$	17,467
Preliminary allocation of consideration transferred to net assets acquired:
Cash	$	21,300
Working capital, excluding inventory and cash (2)	(5,461		)
Inventories	17,717
Property, plant and equipment	19,786
Other assets	7,760
Notes payable to banks	(21,085		)
Total identifiable net assets	40,017
Bargain purchase gain on acquisition	$	22,550

_____________

(1) The fair values of the Company's 59.3% equity interest and the noncontrolling interest were estimated using internally developed, unobservable inputs (Level 3 inputs in the fair value hierarchy of fair value accounting) based on a cost approach.

(2) The fair value of accounts receivable acquired is $2,515, with the gross contractual amount being $3,006. The Company expects $491 to be uncollectible.

XML

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 188,420	$ 170,156	$ 548,888	$ 497,631
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	(22)	(31)	(208)	(62)
Amortization of benefits liability	692	240	2,019	685
Income tax provision on pension and other post-retirement benefits liability	(232)	(81)	(621)	(240)
Foreign currency translation adjustments	(1,920)	(37,792)	(43,746)	(37,882)
Available-for-sale investments
Unrealized holding (losses) gains on investments	(716)	2,129	3,987	6,960
Reclassification of net realized gain to net income	0	0	(3,795)	(1,212)
Income tax benefit (provision) on available- for-sale investments	257	(766)	(68)	(2,066)
Other comprehensive loss	(1,941)	(36,301)	(42,432)	(33,817)
Comprehensive income	186,479	133,855	506,456	463,814
Comprehensive income attributable to noncontrolling interests, net of tax	4,816	2,399	13,847	2,399
Comprehensive income attributable to Westlake Chemical Corporation	$ 181,663	$ 131,456	$ 492,609	$ 461,415

XML

Inventories

9 Months Ended

Sep. 30, 2015

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories consist of the following:

	September 30, 2015		December 31, 2014
Finished products	$	238,671	$	300,909
Feedstock, additives and chemicals	118,498		158,635
Materials and supplies	72,837		66,232
Inventories	$	430,006	$	525,776

XML

Pension and Post-Retirement Benefit Costs (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
United States Pension Plan of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 83	$ 29	$ 250
Interest cost	487	576	1,519	1,747
Expected return on plan assets	(712)	(777)	(2,237)	(2,363)
Amortization of prior service cost	0	74	0	223
Amortization of net loss	333	71	942	204
Net periodic benefit cost	108	27	253	61
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	416	248	1,248	248
Interest cost	528	562	1,585	562
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Amortization of net loss	263	0	789	0
Net periodic benefit cost	1,207	810	3,622	810
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	6	17	16
Interest cost	149	185	448	548
Amortization of prior service cost	0	13	0	38
Amortization of net loss	96	82	288	220
Net periodic benefit cost	$ 251	$ 286	$ 753	$ 822

XML

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net income	$ 188,420	$ 170,156	$ 548,888	$ 497,631
Depreciation and amortization			181,733	149,566
Deferred income taxes			7,585	34,459
Net changes in working capital and other			103,094	94,468
Net cash provided by operating activities			841,300	776,124
Acquisition of business, net of cash acquired			15,782	(611,087)
Acquisition of business				(611,087)
Additions to property, plant and equipment	(125,304)	(94,271)	(329,236)	(311,183)
Proceeds from disposition of assets			17	145
Proceeds from repayment of loan acquired			0	45,923
Proceeds from disposition of equity method investment			27,865	0
Proceeds from sales and maturities of securities			16,056	342,045
Purchase of securities			(282,542)	(117,332)
Settlements of derivative instruments			(1,535)	(689)
Net cash used for investing activities			(553,593)	(652,178)
Intercompany financing			0	0
Intercompany financing—OpCo			0
Net distributions prior to Westlake Partners initial public offering				0
Capitalized debt issuance costs			0	(1,167)
Dividends paid			(67,852)	(55,690)
Distributions paid			(10,982)
Net proceeds from issuance of Westlake Partners common units			0	286,088
Purchase of limited partner interests				0
Proceeds from exercise of stock options			984	5,502
Proceeds from issuance of notes payable			19,483	0
Repayment of notes payable			(32,954)	0
Repurchase of common stock for treasury			(114,254)	(9,495)
Windfall tax benefits from share-based payment arrangements			2,452	6,670
Net cash provided by financing activities			(203,123)	231,908
Effect of exchange rate changes on cash and cash equivalents			(3,260)	(3,687)
Net increase in cash and cash equivalents			81,324	352,167
Cash and cash equivalents at beginning of period			880,601	461,301
Cash and cash equivalents at end of period	961,925	813,468	961,925	813,468
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net income	183,604	167,757	535,041	495,232
Depreciation and amortization			1,504	1,172
Deferred income taxes			87	(418)
Net changes in working capital and other			(567,137)	(509,862)
Net cash provided by operating activities			(30,505)	(13,876)
Acquisition of business, net of cash acquired			0
Acquisition of business				0
Additions to property, plant and equipment			0	0
Proceeds from disposition of assets			0	0
Proceeds from repayment of loan acquired				0
Proceeds from disposition of equity method investment			0
Proceeds from sales and maturities of securities			16,056	342,045
Purchase of securities			(282,542)	(117,332)
Settlements of derivative instruments			0	0
Net cash used for investing activities			(266,486)	224,713
Intercompany financing			467,360	75,104
Intercompany financing—OpCo			0
Net distributions prior to Westlake Partners initial public offering				0
Capitalized debt issuance costs				(1,167)
Dividends paid			(67,852)	(55,690)
Distributions paid			0
Net proceeds from issuance of Westlake Partners common units				0
Purchase of limited partner interests				0
Proceeds from exercise of stock options			984	5,502
Proceeds from issuance of notes payable			0
Repayment of notes payable			0
Repurchase of common stock for treasury			(114,254)	(9,495)
Windfall tax benefits from share-based payment arrangements			2,452	6,670
Net cash provided by financing activities			288,690	20,924
Effect of exchange rate changes on cash and cash equivalents			0	0
Net increase in cash and cash equivalents			(8,301)	231,761
Cash and cash equivalents at beginning of period			655,947	420,948
Cash and cash equivalents at end of period	647,646	652,709	647,646	652,709
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	169,422	175,009	473,663	509,404
Depreciation and amortization			90,247	82,597
Deferred income taxes			4,184	26,991
Net changes in working capital and other			(251,423)	(919,521)
Net cash provided by operating activities			316,671	(300,529)
Acquisition of business, net of cash acquired			0
Acquisition of business				0
Additions to property, plant and equipment			(148,055)	(160,147)
Proceeds from disposition of assets			0	144
Proceeds from repayment of loan acquired				0
Proceeds from disposition of equity method investment			27,865
Proceeds from sales and maturities of securities			0	0
Purchase of securities			0	0
Settlements of derivative instruments			(1,535)	(556)
Net cash used for investing activities			(121,725)	(160,559)
Intercompany financing			(577,898)	(143,325)
Intercompany financing—OpCo			135,341
Net distributions prior to Westlake Partners initial public offering				448,101
Capitalized debt issuance costs				0
Dividends paid			0	151,729
Distributions paid			249,999
Net proceeds from issuance of Westlake Partners common units				0
Purchase of limited partner interests				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			(192,558)	456,505
Effect of exchange rate changes on cash and cash equivalents			0	0
Net increase in cash and cash equivalents			2,388	(4,583)
Cash and cash equivalents at beginning of period			3,057	6,227
Cash and cash equivalents at end of period	5,445	1,644	5,445	1,644
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Net income	88,722	119,019	266,621	416,737
Depreciation and amortization			60,637	58,501
Deferred income taxes			(359)	8,267
Net changes in working capital and other			9,315	1,641
Net cash provided by operating activities			336,214	485,146
Acquisition of business, net of cash acquired			0
Acquisition of business				0
Additions to property, plant and equipment			(152,572)	(144,348)
Proceeds from disposition of assets			0	0
Proceeds from repayment of loan acquired				0
Proceeds from disposition of equity method investment			0
Proceeds from sales and maturities of securities			0	0
Purchase of securities			0	0
Settlements of derivative instruments			0	(133)
Net cash used for investing activities			(152,572)	(144,481)
Intercompany financing			102,857	62,221
Intercompany financing—OpCo			(135,341)
Net distributions prior to Westlake Partners initial public offering				(448,101)
Capitalized debt issuance costs				0
Dividends paid			0	(151,729)
Distributions paid			(268,562)
Net proceeds from issuance of Westlake Partners common units				0
Purchase of limited partner interests			135,341	286,088
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			(165,705)	(251,521)
Effect of exchange rate changes on cash and cash equivalents			0	0
Net increase in cash and cash equivalents			17,937	89,144
Cash and cash equivalents at beginning of period			131,545	0
Cash and cash equivalents at end of period	149,482	89,144	149,482	89,144
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	25,719	663	85,715	(1,441)
Depreciation and amortization			29,345	7,296
Deferred income taxes			3,673	(381)
Net changes in working capital and other			100,187	599,909
Net cash provided by operating activities			218,920	605,383
Acquisition of business, net of cash acquired			15,782
Acquisition of business				(611,087)
Additions to property, plant and equipment			(28,609)	(6,688)
Proceeds from disposition of assets			17	1
Proceeds from repayment of loan acquired				45,923
Proceeds from disposition of equity method investment			0
Proceeds from sales and maturities of securities			0	0
Purchase of securities			0	0
Settlements of derivative instruments			0	0
Net cash used for investing activities			(12,810)	(571,851)
Intercompany financing			7,681	6,000
Intercompany financing—OpCo			0
Net distributions prior to Westlake Partners initial public offering				0
Capitalized debt issuance costs				0
Dividends paid			0	0
Distributions paid			7,581
Net proceeds from issuance of Westlake Partners common units				286,088
Purchase of limited partner interests			(135,341)	(286,088)
Proceeds from exercise of stock options			0	0
Proceeds from issuance of notes payable			19,483
Repayment of notes payable			(32,954)
Repurchase of common stock for treasury			0	0
Windfall tax benefits from share-based payment arrangements			0	0
Net cash provided by financing activities			(133,550)	6,000
Effect of exchange rate changes on cash and cash equivalents			(3,260)	(3,687)
Net increase in cash and cash equivalents			69,300	35,845
Cash and cash equivalents at beginning of period			90,052	34,126
Cash and cash equivalents at end of period	159,352	69,971	159,352	69,971
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income	(279,047)	(292,292)	(812,152)	(922,301)
Depreciation and amortization			0	0
Deferred income taxes			0	0
Net changes in working capital and other			812,152	922,301
Net cash provided by operating activities			0	0
Acquisition of business, net of cash acquired			0
Acquisition of business				0
Additions to property, plant and equipment			0	0
Proceeds from disposition of assets			0	0
Proceeds from repayment of loan acquired				0
Proceeds from disposition of equity method investment			0
Proceeds from sales and maturities of securities			0	0
Purchase of securities			0	0
Settlements of derivative instruments			0	0
Net cash used for investing activities			0	0
Intercompany financing			0	0
Intercompany financing—OpCo			0
Net distributions prior to Westlake Partners initial public offering				0
Capitalized debt issuance costs				0
Dividends paid			0	0
Distributions paid			0
Net proceeds from issuance of Westlake Partners common units				0
Purchase of limited partner interests				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 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	$ 0	$ 0

XML

Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Weighted average common shares—basic	131,664,296	133,299,458	132,301,814	133,199,304
Plus incremental shares from: Assumed exercise of options	456,939	546,601	484,720	543,841
Weighted average common shares-diluted	132,121,235	133,846,059	132,786,534	133,743,145
Earnings per share: Basic (usd per share)	$ 1.39	$ 1.26	$ 4.04	$ 3.71
Earnings per share: Diluted (usd per share)	$ 1.39	$ 1.25	$ 4.02	$ 3.69

XML

Subsequent Events

9 Months Ended

Sep. 30, 2015

Subsequent Events [Abstract]

Subsequent Events

Subsequent Events

Subsequent events were evaluated through the date on which the financial statements were issued.

XML

Commitments and Contingencies (Additional Information) (Detail) - USD ($) $ in Thousands	12 Months Ended	98 Months Ended
	Dec. 31, 2014	Sep. 30, 2015
Unfavorable Regulatory Action [Member]
Commitments and Contingencies Disclosure [Line Items]
Possible amount of claims in settlement for compliance violations		$ 200
Goodrich And PolyOne [Member]
Commitments and Contingencies Disclosure [Line Items]
Costs incurred for environmental remediation services	$ 2,805
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

XML

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2015

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:

	September 30, 2015
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	4,700		$	39		$	4,739
Risk management liabilities—Commodity forward contracts	(8,395		)	(6,872		)	(15,267		)
Marketable securities
Available-for-sale securities	57,733			232,091			289,824
	December 31, 2014
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	3,143		$	2		$	3,145
Risk management liabilities—Commodity forward contracts	—			(10,108		)	(10,108		)
Marketable securities
Available-for-sale securities	15,414			—			15,414

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.

	September 30, 2015				December 31, 2014
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	249,197	$	246,843	$	249,108	$	248,630
6 ½% senior notes due 2029	100,000		116,663		100,000		116,384
6 ¾% senior notes due 2032	250,000		273,655		250,000		285,545
6 ½% GO Zone Senior Notes Due 2035	89,000		103,740		89,000		106,504
6 ½% IKE Zone Senior Notes Due 2035	65,000		74,719		65,000		77,784
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

XML

Income Taxes

9 Months Ended

Sep. 30, 2015

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

The effective income tax rate was 24.2% for the three months ended September 30, 2015. The effective income tax rate for the three months ended September 30, 2015 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, the foreign earnings rate differential, the increased benefit in certain prior years' deductions due to a change in the calculation methodology of the domestic manufacturing deduction and adjustments related to prior years' tax returns as filed, partially offset by state income taxes. The effective income tax rate was 42.2% for the three months ended September 30, 2014. The effective income tax rate for the three months ended September 30, 2014 was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.

The effective income tax rate was 30.1% for the nine months ended September 30, 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, the non-recognition of tax related to the bargain purchase of a controlling interest in Suzhou Huasu Plastics Co., Ltd., the increased benefit in certain prior years' deductions due to a change in the calculation methodology of the domestic manufacturing deduction and adjustments related to prior years' tax returns as filed and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 37.6% for the nine months ended September 30, 2014. The effective income tax rate for the 2014 period was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.

There were no unrecognized tax benefits for the nine months ended September 30, 2015. The Company recognizes penalties and interest accrued related to unrecognized tax benefits in income tax expense. As of September 30, 2015, 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.