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 June 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 July 29, 2015 was 131,938,403.

INDEX

Item	Page
PART I. FINANCIAL INFORMATION
1) Financial Statements	1
2) Management's Discussion and Analysis of Financial Condition and Results of Operations	29
3) Quantitative and Qualitative Disclosures about Market Risk	39
4) Controls and Procedures	39
PART II. OTHER INFORMATION
1) Legal Proceedings	40
1A) Risk Factors	40
2) Unregistered Sales of Equity Securities and Use of Proceeds	40
6) Exhibits	41

PART I. FINANCIAL INFORMATION

Item 1. Financial Statements

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED BALANCE SHEETS

(Unaudited)

	June 30, 2015			December 31, 2014
	(in thousands of dollars, except par values and share amounts)
ASSETS
Current assets
Cash and cash equivalents	$	1,026,569		$	880,601
Accounts receivable, net	600,722			560,666
Inventories	486,297			525,776
Prepaid expenses and other current assets	23,018			11,807
Deferred income taxes	29,634			32,437
Total current assets	2,166,240			2,011,287
Property, plant and equipment, net	2,855,508			2,757,557
Equity investments	37,746			61,305
Other assets, net
Intangible assets, net	213,968			218,431
Deferred charges and other assets, net	137,548			165,410
Total other assets, net	351,516			383,841
Total assets	$	5,411,010		$	5,213,990
LIABILITIES AND EQUITY
Current liabilities
Accounts and notes payable	$	282,978		$	261,062
Accrued liabilities	251,680			276,118
Total current liabilities	534,658			537,180
Long-term debt	764,056			763,997
Deferred income taxes	532,344			536,066
Other liabilities	162,777			174,859
Total liabilities	1,993,835			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;    134,679,064 shares issued at June 30, 2015 and December 31, 2014	1,347			1,347
Common stock, held in treasury, at cost; 2,646,260 and 1,787,546 shares    at June 30, 2015 and December 31, 2014, respectively	(158,472		)	(96,372		)
Additional paid-in capital	537,368			530,441
Retained earnings	2,863,069			2,555,528
Accumulated other comprehensive loss	(119,924		)	(79,433		)
Total Westlake Chemical Corporation stockholders' equity	3,123,388			2,911,511
Noncontrolling interests	293,787			290,377
Total equity	3,417,175			3,201,888
Total liabilities and equity	$	5,411,010		$	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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
	(in thousands of dollars, except per share data and share amounts)
Net sales	$	1,185,002		$	998,576		$	2,288,533		$	2,026,252
Cost of sales	831,821			692,605			1,650,806			1,433,271
Gross profit	353,181			305,971			637,727			592,981
Selling, general and administrative expenses	57,807			39,183			113,073			78,138
Income from operations	295,374			266,788			524,654			514,843
Other income (expense)
Interest expense	(8,958		)	(9,539		)	(18,549		)	(18,696		)
Other income, net	22,058			4,601			31,154			7,110
Income before income taxes	308,474			261,850			537,259			503,257
Provision for income taxes	98,413			92,407			176,791			175,782
Net income	210,061			169,443			360,468			327,475
Net income attributable to noncontrolling interests	4,966			—			9,031			—
Net income attributable to    Westlake Chemical Corporation	$	205,095		$	169,443		$	351,437		$	327,475
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.55		$	1.27		$	2.65		$	2.45
Diluted	$	1.54		$	1.26		$	2.64		$	2.44
Weighted average common shares outstanding:
Basic	132,538,123			133,223,705			132,625,857			133,148,398
Diluted	133,044,975			133,767,890			133,124,697			133,690,836
Dividends per common share	$	0.1650		$	0.1260		$	0.3300		$	0.2520

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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
	(in thousands of dollars)
Net income	$	210,061		$	169,443		$	360,468		$	327,475
Other comprehensive (loss) income, net of income taxes
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves    adjustment (excluding amortization)	(186		)	(31		)	(186		)	(31		)
Amortization of benefits liability	675			226			1,327			445
Income tax provision on pension and other    post-retirement benefits liability	(164		)	(75		)	(389		)	(159		)
Foreign currency translation adjustments	17,872			808			(41,826		)	(90		)
Available-for-sale investments
Unrealized holding gains on investments	3,077			2,364			4,703			4,831
Reclassification of net realized gain to    net income	(3,795		)	(1,237		)	(3,795		)	(1,212		)
Income tax benefit (provision) on available-    for-sale investments	259			(405		)	(325		)	(1,300		)
Other comprehensive income (loss)	17,738			1,650			(40,491		)	2,484
Comprehensive income	227,799			171,093			319,977			329,959
Comprehensive income attributable to    noncontrolling interests, net of tax	4,966			—			9,031			—
Comprehensive income attributable to    Westlake Chemical Corporation	$	222,833		$	171,093		$	310,946		$	329,959

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

3

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

	Six Months Ended June 30,
	2015			2014
	(in thousands of dollars)
Cash flows from operating activities
Net income	$	360,468		$	327,475
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	118,981			94,474
Recovery of doubtful accounts	228			311
Amortization of debt issuance costs	1,002			730
Stock-based compensation expense	4,905			4,511
Loss from disposition of fixed assets	890			1,872
Gain from sales of equity 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	3,088			19,359
Windfall tax benefits from share-based payment arrangements	(1,895		)	(4,436		)
Income from equity method investments, net of dividends	(1,760		)	(1,239		)
Other gains (losses), net	423			(526		)
Changes in operating assets and liabilities
Accounts receivable	(22,380		)	(27,367		)
Inventories	50,115			34,360
Prepaid expenses and other current assets	(10,844		)	(5,480		)
Accounts payable	(2,327		)	(21,990		)
Accrued liabilities	(40,526		)	13,631
Other, net	(5,098		)	(3,443		)
Net cash provided by operating activities	435,355			432,242
Cash flows from investing activities
Acquisition of business, net of cash acquired	15,782			—
Additions to property, plant and equipment	(203,933		)	(216,912		)
Proceeds from disposition of assets	—			13
Proceeds from sales and maturities of securities	15,037			342,045
Purchase of securities	—			(117,332		)
Settlements of derivative instruments	(1,174		)	(290		)
Net cash (used for) provided by investing activities	(174,288		)	7,524
Cash flows from financing activities
Dividends paid	(43,896		)	(33,623		)
Distributions to noncontrolling interests	(7,218		)	—
Proceeds from exercise of stock options	831			4,187
Proceeds from issuance of notes payable	2,392			—
Repayment of notes payable	(4,299		)	—
Repurchase of common stock for treasury	(62,804		)	—
Windfall tax benefits from share-based payment arrangements	1,895			4,436
Net cash used for financing activities	(113,099		)	(25,000		)
Effect of exchange rate changes on cash and cash equivalents	(2,000		)	—
Net increase in cash and cash equivalents	145,968			414,766
Cash and cash equivalents at beginning of period	880,601			461,301
Cash and cash equivalents at end of period	$	1,026,569		$	876,067

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 June 30, 2015, its results of operations for the three and six months ended June 30, 2015 and 2014 and the changes in its cash position for the six months ended June 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 interim periods within those fiscal years, and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows.

2. Financial Instruments

Cash Equivalents

The Company had $654,739 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 June 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:

	June 30, 2015		December 31, 2014
Non-current	$	5,074	$	15,414
Total available-for-sale securities	$	5,074	$	15,414

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

	June 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	3,802	$	1,272	$	—	$	5,074
Total available-for-sale securities	$	3,802	$	1,272	$	—	$	5,074

	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 June 30, 2015 and December 31, 2014, net unrealized gains on the Company's available-for-sale securities of $816 and $233, respectively, net of income tax expense of $456 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.

6

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 June 30,					Six Months Ended June 30,
	2015		2014			2015		2014
Proceeds from sales and maturities of securities	$	15,037	$	311,926		$	15,037	$	342,045
Gross realized gains	3,795		1,298			3,795		1,311
Gross realized losses	—		(61		)	—		(99		)

3. Accounts Receivable

Accounts receivable consist of the following:

	June 30, 2015			December 31, 2014
Trade customers	$	575,609		$	525,546
Affiliates	—			437
Allowance for doubtful accounts	(13,468		)	(13,468		)
	562,141			512,515
Federal and state taxes	11,746			8,919
Other	26,835			39,232
Accounts receivable, net	$	600,722		$	560,666

4. Inventories

Inventories consist of the following:

	June 30, 2015		December 31, 2014
Finished products	$	280,317	$	300,909
Feedstock, additives and chemicals	134,369		158,635
Materials and supplies	71,611		66,232
Inventories	$	486,297	$	525,776

5. Property, Plant and Equipment

As of June 30, 2015, the Company had property, plant and equipment, net totaling $2,855,508. 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 $51,263 and $39,859 is included in cost of sales in the consolidated statements of operations for the three months ended June 30, 2015 and 2014, respectively. Depreciation expense on property, plant and equipment of $100,921 and $77,920 is included in cost of sales in the consolidated statements of operations for the six months ended June 30, 2015 and 2014, respectively.

7

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 $9,578 and $9,008 is included in the consolidated statements of operations for the three months ended June 30, 2015 and 2014, respectively. Amortization expense on intangible and other assets of $19,062 and $17,284 is included in the consolidated statements of operations for the six months ended June 30, 2015 and 2014, respectively.

Goodwill

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

7. Accounts and Notes Payable

Accounts and notes payable consist of the following:

	June 30, 2015		December 31, 2014
Accounts payable	$	263,803	$	261,062
Notes payable to banks	19,175		—
Accounts and notes payable	$	282,978	$	261,062

8. Long-Term Debt

Long-term debt consists of the following:

	June 30, 2015		December 31, 2014
3.60% senior notes due 2022	$	249,167	$	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	$	764,056	$	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 June 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 June 30, 2015, the Company had outstanding letters of credit totaling $29,670 and borrowing availability of $370,330 under the revolving credit facility.

8

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 six months ended June 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	—		—			—		351,437			—			9,031			360,468
Other comprehensive income    (loss), net of income taxes:
Pension and other post-    retirement benefits    liability	—		—			—		—			752			—			752
Foreign currency    translation adjustments	—		—			—		—			(41,826		)	—			(41,826		)
Net unrealized holding    gains on investments	—		—			—		—			583			—			583
Common stock repurchased	—		(62,804		)	—		—			—			—			(62,804		)
Shares issued—stock-    based compensation	—		704			127		—			—			—			831
Stock-based compensation,    net of tax on stock options    exercised	—		—			6,800		—			—			—			6,800
Dividends paid	—		—			—		(43,896		)	—			—			(43,896		)
Distributions to noncontrolling    interests	—		—			—		—			—			(7,218		)	(7,218		)
Noncontrolling interest in    acquired business	—		—			—		—			—			1,597			1,597
Balances at June 30, 2015	$	1,347	$	(158,472	)	$	537,368	$	2,863,069		$	(119,924	)	$	293,787		$	3,417,175

	Common Stock		Common Stock, Held in Treasury			Additional Paid-in Capital		Retained Earnings			Accumulated Other Comprehensive  Income (Loss)			Total
Balances at December 31, 2013	$	1,346	$	(46,220	)	$	511,432	$	1,954,661		$	(2,616	)	$	2,418,603
Net income	—		—			—		327,475			—			327,475
Other comprehensive income (loss), net of    income taxes:
Pension and other post-retirement benefits    liability	—		—			—		—			255			255
Foreign currency translation adjustments	—		—			—		—			(90		)	(90		)
Net unrealized holding gains on    investments	—		—			—		—			2,319			2,319
Shares issued—stock-based compensation	1		1,039			3,147		—			—			4,187
Stock-based compensation, net of tax on stock    options exercised	—		—			8,947		—			—			8,947
Dividends paid	—		—			—		(33,623		)	—			(33,623		)
Balances at June 30, 2014	$	1,347	$	(45,181	)	$	523,526	$	2,248,513		$	(132	)	$	2,728,073

9

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 six months ended June 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	(115		)	(41,826		)	3,015			(38,926		)
Amounts reclassified from accumulated other    comprehensive loss (income)	867			—			(2,432		)	(1,565		)
Net other comprehensive income (loss) for the period	752			(41,826		)	583			(40,491		)
Balances at June 30, 2015	$	(22,690	)	$	(98,050	)	$	816		$	(119,924	)

	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	(20		)	(90		)	3,096			2,986
Amounts reclassified from accumulated other    comprehensive loss	275			—			(777		)	(502		)
Net other comprehensive income (loss) for the period	255			(90		)	2,319			2,484
Balances at June 30, 2014	$	(6,441	)	$	3,814		$	2,495		$	(132	)

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 six months ended June 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 June 30,						Six Months Ended June 30,
		2015			2014			2015			2014
Amortization of pension and    other post-retirement items
Prior service costs	(1)	$	—		$	(87	)	$	—		$	(173	)
Net loss	(1)	(675		)	(139		)	(1,327		)	(272		)
		(675		)	(226		)	(1,327		)	(445		)
	Provision for income    taxes	235			86			460			170
		(440		)	(140		)	(867		)	(275		)
Net unrealized gains on    available-for-sale    investments
Realized gain on    available-for-sale    investments	Other income, net	3,795			1,237			3,795			1,212
	Provision for income    taxes	(1,363		)	(444		)	(1,363		)	(435		)
		2,432			793			2,432			777
Total reclassifications for    the period		$	1,992		$	653		$	1,565		$	502

10

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 June 30,								Six Months Ended June 30,
	2015					2014			2015					2014
	U.S. Plans			Non-U.S. Plans		U.S. Plans			U.S. Plans			Non-U.S. Plans		U.S. Plans
Service cost	$	1		$	414	$	84		$	29		$	835	$	167
Interest cost	489			525		576			1,032			1,061		1,170
Expected return on plan assets	(705		)	—		(777		)	(1,524		)	—		(1,586		)
Amortization of prior service cost	—			—		74			—			—		148
Amortization of net loss	318			261		70			609			526		134
Net periodic benefit cost	$	103		$	1,200	$	27		$	146		$	2,422	$	33

The Company made no contribution to the U.S. salaried pension plan in the first six months of 2015. The Company contributed $965 to the U.S. salaried pension plan in the first six months of 2014. The Company contributed $349 and $580 to the U.S. wage pension plan in the first six 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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
	U.S. Plans		U.S. Plans		U.S. Plans		U.S. Plans
Service cost	$	6	$	5	$	11	$	11
Interest cost	149		181		299		362
Amortization of prior service cost	—		13		—		25
Amortization of net loss	96		69		192		138
Net periodic benefit cost	$	251	$	268	$	502	$	536

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 $2,565 and $2,289 for the three months ended June 30, 2015 and 2014,respectively, and $4,905 and $4,511 for the six months ended June 30, 2015 and 2014, respectively.

11

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 six months ended June 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 six months ended June 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 June 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
		June 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	2,439	$	3,145
Commodity forward contracts	Deferred charges and    other assets, net	2,433		—
Total derivative assets		$	4,872	$	3,145

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		June 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	3,446	$	6,549
Commodity forward contracts	Other liabilities	3,047		3,559
Total derivative liabilities		$	6,493	$	10,108

12

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 June 30,				Six Months Ended June 30,
		2015		2014		2015		2014
Commodity forward contracts	Gross profit	$	595	$	240	$	4,836	$	(371	)

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:

	June 30, 2015
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	3,958		$	914		$	4,872
Risk management liabilities—Commodity forward contracts	(1,825		)	(4,668		)	(6,493		)
Marketable securities
Available-for-sale securities	5,074			—			5,074
	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.

There were no transfers in or out of Levels 1 and 2 of the fair value hierarchy for the six months ended June 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.

13

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

	June 30, 2015				December 31, 2014
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	249,167	$	251,118	$	249,108	$	248,630
6 ½% senior notes due 2029	100,000		119,018		100,000		116,384
6 ¾% senior notes due 2032	250,000		277,375		250,000		285,545
6 ½% GO Zone Senior Notes Due 2035	89,000		104,498		89,000		106,504
6 ½% IKE Zone Senior Notes Due 2035	65,000		75,485		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 32.9% for the six months ended June 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. and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 34.9% for the six months ended June 30, 2014. The effective income tax rate for the 2014 period was below the U.S. federal statutory rate of 35.0% primarily due to state tax credits and the domestic manufacturing deduction, mostly offset by state income taxes.

There were no unrecognized tax benefits for the six months ended June 30, 2015. The Company recognizes penalties and interest accrued related to unrecognized tax benefits in income tax expense. As of June 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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Net income attributable to    Westlake Chemical Corporation	$	205,095		$	169,443		$	351,437		$	327,475
Less:
Net income attributable to participating securities	(253		)	(360		)	(457		)	(746		)
Net income attributable to common shareholders	$	204,842		$	169,083		$	350,980		$	326,729

14

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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Weighted average common shares—basic	132,538,123		133,223,705		132,625,857		133,148,398
Plus incremental shares from:
Assumed exercise of options	506,852		544,185		498,840		542,438
Weighted average common shares—diluted	133,044,975		133,767,890		133,124,697		133,690,836
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.55	$	1.27	$	2.65	$	2.45
Diluted	$	1.54	$	1.26	$	2.64	$	2.44

Excluded from the computation of diluted earnings per share are options to purchase 330,315 and 134,938 shares of common stock for the three months ended June 30, 2015 and 2014, respectively, and 285,933 and 102,480 shares of common stock for the six months ended June 30, 2015 and 2014, respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive.

16. Supplemental Information

Accrued Liabilities

Accrued liabilities were $251,680 and $276,118 at June 30, 2015 and December 31, 2014, respectively. Accrued rebates and accrued incentive compensation, which are components of accrued liabilities, were $30,428 and $34,278 at June 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 $162,777 and $174,859 at June 30, 2015 and December 31, 2014, respectively. Non-current pension obligation, which is a component of other liabilities, was $126,708 and $136,296 at June 30, 2015 and December 31, 2014, respectively. No other component of other liabilities was more than five percent of total liabilities.

Other Income, Net

	Three Months Ended June 30,					Six Months Ended June 30,
	2015			2014		2015			2014
Interest income	$	866		$	1,105	$	1,751		$	2,328
Dividend income	1,357			—		3,329			—
Foreign exchange currency (losses) gains, net	(500		)	3		1,871			(245		)
(Loss) income from equity method investments	(350		)	1,920		4,613			3,941
Impairment of equity method investment	(4,925		)	—		(4,925		)	—
Gain on acquisition and related expenses, net	20,430			—		20,430			—
Gain from sales of equity securities	3,795			—		3,795			—
Other	1,385			1,573		290			1,086
Other income, net	$	22,058		$	4,601	$	31,154		$	7,110

15

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, 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, 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 six months ended June 30, 2015. The acquisition-related costs recognized in the consolidated statements of operations for the three and six months ended June 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 six months ended June 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.

16

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 quarter 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. The Company recognized approximately $4,470 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 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.

17

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

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.

18

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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Net external sales
Olefins
Polyethylene	$	450,482		$	475,503		$	859,914		$	962,647
Styrene, feedstock and other	170,396			223,550			344,041			459,204
Total Olefins	620,878			699,053			1,203,955			1,421,851
Vinyls
PVC, caustic soda and other	429,878			168,762			846,866			359,289
Building products	134,246			130,761			237,712			245,112
Total Vinyls	564,124			299,523			1,084,578			604,401
	$	1,185,002		$	998,576		$	2,288,533		$	2,026,252
Intersegment sales
Olefins	$	26,641		$	34,782		$	50,103		$	91,635
Vinyls	387			331			757			674
	$	27,028		$	35,113		$	50,860		$	92,309
Income (loss) from operations
Olefins	$	220,938		$	238,657		$	412,041		$	510,990
Vinyls	87,966			38,129			135,052			17,015
Corporate and other	(13,530		)	(9,998		)	(22,439		)	(13,162		)
	$	295,374		$	266,788		$	524,654		$	514,843
Depreciation and amortization
Olefins	$	27,623		$	26,721		$	54,562		$	53,368
Vinyls	32,599			21,623			64,183			40,791
Corporate and other	118			158			236			315
	$	60,340		$	48,502		$	118,981		$	94,474
Other income (expense), net
Olefins	$	(104	)	$	1,199		$	2,448		$	2,653
Vinyls	1,413			(213		)	6,916			(247		)
Corporate and other	20,749			3,615			21,790			4,704
	$	22,058		$	4,601		$	31,154		$	7,110
Provision for (benefit from) income taxes
Olefins	$	74,212		$	83,502		$	140,669		$	177,052
Vinyls	26,653			10,430			39,458			360
Corporate and other	(2,452		)	(1,525		)	(3,336		)	(1,630		)
	$	98,413		$	92,407		$	176,791		$	175,782
Capital expenditures
Olefins	$	81,534		$	43,448		$	136,835		$	72,522
Vinyls	24,569			62,262			61,425			143,382
Corporate and other	2,007			461			5,673			1,008
	$	108,110		$	106,171		$	203,933		$	216,912

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Income from operations	$	295,374		$	266,788		$	524,654		$	514,843
Interest expense	(8,958		)	(9,539		)	(18,549		)	(18,696		)
Other income, net	22,058			4,601			31,154			7,110
Income before income taxes	$	308,474		$	261,850		$	537,259		$	503,257

	June 30, 2015		December 31, 2014
Total assets
Olefins	$	1,844,391	$	1,785,895
Vinyls	2,656,936		2,618,646
Corporate and other	909,683		809,449
	$	5,411,010	$	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.

19

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 June 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	$	756,385	$	3,923	$	133,890	$	132,371	$	—		$	1,026,569
Accounts receivable, net	13,335		1,995,787		57,957		144,560		(1,610,917		)	600,722
Inventories	—		376,750		3,856		105,691		—			486,297
Prepaid expenses and other current assets	136		20,981		30		4,132		(2,261		)	23,018
Deferred income taxes	409		29,832		—		279		(886		)	29,634
Total current assets	770,265		2,427,273		195,733		387,033		(1,614,064		)	2,166,240
Property, plant and equipment, net	—		1,520,734		914,270		420,504		—			2,855,508
Equity investments	4,690,426		1,228,964		—		467,530		(6,349,174		)	37,746
Other assets, net	18,920		300,172		50,018		133,840		(151,434		)	351,516
Total assets	$	5,479,611	$	5,477,143	$	1,160,021	$	1,408,907	$	(8,114,672	)	$	5,411,010
Current liabilities
Accounts and notes payable	$	1,594,555	$	145,719	$	36,339	$	104,954	$	(1,598,589	)	$	282,978
Accrued liabilities	8,501		173,112		16,441		69,101		(15,475		)	251,680
Total current liabilities	1,603,056		318,831		52,780		174,055		(1,614,064		)	534,658
Long-term debt	753,167		10,889		145,651		—		(145,651		)	764,056
Deferred income taxes	—		498,993		1,614		37,520		(5,783		)	532,344
Other liabilities	—		39,553		—		123,224		—			162,777
Total liabilities	2,356,223		868,266		200,045		334,799		(1,765,498		)	1,993,835
Total Westlake Chemical Corporation stockholders' equity	3,123,388		4,608,877		959,976		780,321		(6,349,174		)	3,123,388
Noncontrolling interests	—		—		—		293,787		—			293,787
Total equity	3,123,388		4,608,877		959,976		1,074,108		(6,349,174		)	3,417,175
Total liabilities and equity	$	5,479,611	$	5,477,143	$	1,160,021	$	1,408,907	$	(8,114,672	)	$	5,411,010

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 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

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 for the Three Months Ended June 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	$	—		$	990,434		$	251,705		$	250,365		$	(307,502	)	$	1,185,002
Cost of sales	—			750,892			157,177			226,283			(302,531		)	831,821
Gross profit	—			239,542			94,528			24,082			(4,971		)	353,181
Selling, general and administrative expenses	399			42,682			5,191			14,506			(4,971		)	57,807
(Loss) income from operations	(399		)	196,860			89,337			9,576			—			295,374
Interest expense	(10,569		)	(4		)	(856		)	(52		)	2,523			(8,958		)
Other income (expense), net	9,776			(9,371		)	34			24,142			(2,523		)	22,058
(Loss) income before income taxes	(1,192		)	187,485			88,515			33,666			—			308,474
(Benefit from) provision for income taxes	(399		)	97,218			(41		)	1,635			—			98,413
Equity in net income of subsidiaries	205,888			76,799			—			11,757			(294,444		)	—
Net income	205,095			167,066			88,556			43,788			(294,444		)	210,061
Net income attributable to noncontrolling interests	—			—			—			4,966			—			4,966
Net income attributable to Westlake Chemical Corporation	$	205,095		$	167,066		$	88,556		$	38,822		$	(294,444	)	$	205,095
Comprehensive income attributable to    Westlake Chemical Corporation	$	222,833		$	167,206		$	88,556		$	56,879		$	(312,641	)	$	222,833

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 June 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	$	—		$	879,842		$	524,135		$	11,753		$	(417,154	)	$	998,576
Cost of sales	—			821,234			277,589			10,936			(417,154		)	692,605
Gross profit	—			58,608			246,546			817			—			305,971
Selling, general and administrative expenses	529			31,066			6,165			1,423			—			39,183
(Loss) income from operations	(529		)	27,542			240,381			(606		)	—			266,788
Interest expense	(9,535		)	(4		)	(4,105		)	—			4,105			(9,539		)
Other income (expense), net	7,137			965			1,397			(793		)	(4,105		)	4,601
(Loss) income before income taxes	(2,927		)	28,503			237,673			(1,399		)	—			261,850
(Benefit from) provision for income taxes	(1,039		)	9,766			83,829			(149		)	—			92,407
Equity in net income of subsidiaries	171,331			153,844			—			—			(325,175		)	—
Net income (loss) attributable to Westlake Chemical Corporation	$	169,443		$	172,581		$	153,844		$	(1,250	)	$	(325,175	)	$	169,443
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	171,093		$	172,701		$	153,844		$	(442	)	$	(326,103	)	$	171,093

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 Six Months Ended June 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	$	—		$	1,901,365		$	510,096		$	496,007		$	(618,935	)	$	2,288,533
Cost of sales	—			1,485,728			319,341			454,553			(608,816		)	1,650,806
Gross profit	—			415,637			190,755			41,454			(10,119		)	637,727
Selling, general and administrative expenses	812			86,366			10,237			25,777			(10,119		)	113,073
(Loss) income from operations	(812		)	329,271			180,518			15,677			—			524,654
Interest expense	(21,321		)	(5		)	(2,232		)	(94		)	5,103			(18,549		)
Other income (expense), net	16,387			(6,544		)	39			26,375			(5,103		)	31,154
(Loss) income before income taxes	(5,746		)	322,722			178,325			41,958			—			537,259
(Benefit from) provision for income taxes	(1,976		)	175,170			426			3,171			—			176,791
Equity in net income of subsidiaries	355,207			156,690			—			21,209			(533,106		)	—
Net income	351,437			304,242			177,899			59,996			(533,106		)	360,468
Net income attributable to noncontrolling interests	—			—			—			9,031			—			9,031
Net income attributable to Westlake Chemical Corporation	$	351,437		$	304,242		$	177,899		$	50,965		$	(533,106	)	$	351,437
Comprehensive income attributable to    Westlake Chemical Corporation	$	310,946		$	304,620		$	177,899		$	9,513		$	(492,032	)	$	310,946

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 Six Months Ended June 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	$	—		$	1,724,184		$	1,084,149		$	20,870		$	(802,951	)	$	2,026,252
Cost of sales	—			1,611,811			605,289			19,122			(802,951		)	1,433,271
Gross profit	—			112,373			478,860			1,748			—			592,981
Selling, general and administrative expenses	1,075			60,351			13,943			2,769			—			78,138
(Loss) income from operations	(1,075		)	52,022			464,917			(1,021		)	—			514,843
Interest expense	(18,690		)	(6		)	(7,696		)	—			7,696			(18,696		)
Other income (expense), net	12,351			1,213			2,649			(1,407		)	(7,696		)	7,110
(Loss) income before income taxes	(7,414		)	53,229			459,870			(2,428		)	—			503,257
(Benefit from) provision for income taxes	(2,597		)	16,553			162,152			(326		)	—			175,782
Equity in net income of subsidiaries	332,292			297,718			—			—			(630,010		)	—
Net income (loss) attributable to Westlake Chemical Corporation	$	327,475		$	334,394		$	297,718		$	(2,102	)	$	(630,010	)	$	327,475
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	329,959		$	334,649		$	297,718		$	(2,192	)	$	(630,175	)	$	329,959

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 Six Months Ended June 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	$	351,437		$	304,242		$	177,899		$	59,996		$	(533,106	)	$	360,468
Adjustments to reconcile net income to net cash (used for)    provided by operating activities
Depreciation and amortization	1,002			59,792			40,195			18,994			—			119,983
Deferred income taxes	(40		)	929			(234		)	2,433			—			3,088
Net changes in working capital and other	(371,716		)	(310,600		)	15,748			85,278			533,106			(48,184		)
Net cash (used for) provided by operating activities	(19,317		)	54,363			233,608			166,701			—			435,355
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			—			—			15,782			—			15,782
Additions to property, plant and equipment	—			(95,363		)	(95,514		)	(13,056		)	—			(203,933		)
Proceeds from sales and maturities of securities	15,037			—			—			—			—			15,037
Settlements of derivative instruments	—			(1,174		)	—			—			—			(1,174		)
Net cash provided by (used for) investing activities	15,037			(96,537		)	(95,514		)	2,726			—			(174,288		)
Cash flows from financing activities
Intercompany financing	208,692			(269,281		)	53,354			7,235			—			—
Intercompany financing—OpCo	—			135,341			(135,341		)	—			—			—
Dividends paid	(43,896		)	—			—			—			—			(43,896		)
Distributions paid	—			176,980			(189,103		)	4,905			—			(7,218		)
Purchase of limited partner interests	—			—			135,341			(135,341		)	—			—
Proceeds from exercise of stock options	831			—			—			—			—			831
Proceeds from issuance of notes payable	—			—			—			2,392			—			2,392
Repayment of notes payable	—			—			—			(4,299		)	—			(4,299		)
Repurchase of common stock for treasury	(62,804		)	—			—			—			—			(62,804		)
Windfall tax benefits from share-based payment arrangements	1,895			—			—			—			—			1,895
Net cash provided by (used for) financing activities	$	104,718		$	43,040		$	(135,749	)	$	(125,108	)	$	—		$	(113,099	)

26

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	$	—	$	—	$	—	$	(2,000	)	$	—	$	(2,000	)
Net increase in cash and cash equivalents	100,438		866		2,345		42,319			—		145,968
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	$	756,385	$	3,923	$	133,890	$	132,371		$	—	$	1,026,569

27

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 Six Months Ended June 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)	$	327,475		$	334,394		$	297,718		$	(2,102	)	$	(630,010	)	$	327,475
Adjustments to reconcile net income (loss) to net cash (used for)    provided by operating activities
Depreciation and amortization	730			54,121			39,282			1,071			—			95,204
Deferred income taxes	(292		)	12,931			6,813			(93		)	—			19,359
Net changes in working capital and other	(336,669		)	(336,097		)	35,108			(2,148		)	630,010			(9,796		)
Net cash (used for) provided by operating activities	(8,756		)	65,349			378,921			(3,272		)	—			432,242
Cash flows from investing activities
Additions to property, plant and equipment	—			(110,338		)	(106,191		)	(383		)	—			(216,912		)
Proceeds from disposition of assets	—			12			—			1			—			13
Proceeds from sales and maturities of securities	342,045			—			—			—			—			342,045
Purchase of securities	(117,332		)	—			—			—			—			(117,332		)
Settlements of derivative instruments	—			—			(290		)	—			—			(290		)
Net cash provided by (used for) investing activities	224,713			(110,326		)	(106,481		)	(382		)	—			7,524
Cash flows from financing activities
Intercompany financing	221,745			(329,044		)	104,173			3,126			—			—
Net distributions prior to Westlake Partners initial public offering	—			376,613			(376,613		)	—			—			—
Dividends paid	(33,623		)	—			—			—			—			(33,623		)
Proceeds from exercise of stock options	4,187			—			—			—			—			4,187
Windfall tax benefits from share-based payment arrangements	4,436			—			—			—			—			4,436
Net cash provided by (used for) financing activities	196,745			47,569			(272,440		)	3,126			—			(25,000		)
Net increase (decrease) in cash and cash equivalents	412,702			2,592			—			(528		)	—			414,766
Cash and cash equivalents at beginning of period	420,948			6,227			—			34,126			—			461,301
Cash and cash equivalents at end of period	$	833,650		$	8,819		$	—		$	33,598		$	—		$	876,067

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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 fabricated 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 second 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 second 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, 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.

On April 29, 2015, Westlake Chemical Partners LP ("Westlake Partners") purchased an additional 2.7% newly issued limited partner interest in OpCo for approximately $135.3 million, resulting in Westlake Partners holding approximately an aggregate 13.3% limited partner interest in OpCo and us holding approximately an aggregate 86.7% limited partner interest in OpCo. In order to fund this purchase, Westlake Partners entered into a revolving credit facility with a subsidiary of ours, which has a total borrowing capacity of $300.0 million. See "—Liquidity and Capital Resources—Westlake Partners Credit Arrangements."

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Results of Operations

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
	(dollars in thousands, except per share data)
Net external sales
Olefins
Polyethylene	$	450,482		$	475,503		$	859,914		$	962,647
Styrene, feedstock and other	170,396			223,550			344,041			459,204
Total Olefins	620,878			699,053			1,203,955			1,421,851
Vinyls
PVC, caustic soda and other	429,878			168,762			846,866			359,289
Building products	134,246			130,761			237,712			245,112
Total Vinyls	564,124			299,523			1,084,578			604,401
Total	$	1,185,002		$	998,576		$	2,288,533		$	2,026,252
Income (loss) from operations
Olefins	$	220,938		$	238,657		$	412,041		$	510,990
Vinyls	87,966			38,129			135,052			17,015
Corporate and other	(13,530		)	(9,998		)	(22,439		)	(13,162		)
Total income from operations	295,374			266,788			524,654			514,843
Interest expense	(8,958		)	(9,539		)	(18,549		)	(18,696		)
Other income, net	22,058			4,601			31,154			7,110
Provision for income taxes	98,413			92,407			176,791			175,782
Net income	210,061			169,443			360,468			327,475
Net income attributable to noncontrolling interests	4,966			—			9,031			—
Net income attributable to    Westlake Chemical Corporation	$	205,095		$	169,443		$	351,437		$	327,475
Diluted earnings per share	$	1.54		$	1.26		$	2.64		$	2.44
	Three Months Ended June 30, 2015						Six Months Ended June 30, 2015
	Average Sales Price			Volume			Average Sales Price			Volume
Product sales price and volume percentage change    from prior-year period
Olefins	-29.4		%	+18.2		%	-28.4		%	+13.1		%
Vinyls	-11.3		%	+99.7		%	-11.2		%	+90.6		%
Company average	-24.0		%	+42.6		%	-23.3		%	+36.2		%
	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Average industry prices (1)
Ethane (cents/lb)	6.2			9.8			6.2			10.6
Propane (cents/lb)	10.8			25.2			11.7			28.0
Ethylene (cents/lb) (2)	36.1			55.5			36.3			55.3
Polyethylene (cents/lb) (3)	78.3			109.0			77.5			108.3
Styrene (cents/lb) (4)	65.8			82.2			60.1			84.5
Caustic soda ($/short ton) (5)	576.7			595.0			582.5			587.1
Chlorine ($/short ton) (6)	268.3			232.5			253.8			234.6
PVC (cents/lb) (7)	67.5			69.5			66.5			68.0

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_____________

(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 film over the period as reported by IHS Chemical.

(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 June 30, 2015, net income attributable to Westlake Chemical Corporation was $205.1 million, or $1.54 per diluted share, on net sales of $1.2 billion. This represents an increase in net income attributable to Westlake Chemical Corporation of $35.7 million, or $0.28 per diluted share, compared to the quarter ended June 30, 2014 net income attributable to Westlake Chemical Corporation of $169.4 million, or $1.26 per diluted share, on net sales of $998.6 million. Net income attributable to Westlake Chemical Corporation for the second quarter of 2015 included a net pre-tax gain of $15.5 million, or $0.13 per diluted share, related to the bargain purchase gain from the acquisition of a controlling interest in Huasu and the partial impairment of an equity method investment. The bargain purchase gain on acquisition was non-taxable and lowered our effective tax rate for the second quarter of 2015 from approximately 34.3% to 31.9%. Net sales for the second quarter of 2015increased by $186.4 million compared to net sales for the second quarter of 2014, mainly attributable to sales contributed by Vinnolit, our specialty PVC resin business, which we acquired in July 2014, 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 $295.4 million for the second quarter of 2015 as compared to $266.8 million for the second quarter of 2014. Income from operations for the second quarter of 2015 benefited from improved vinyls integrated product margins, mainly due 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, and the contribution from Vinnolit as compared to the second quarter of 2014. However, this benefit was partially offset by lower olefins integrated product margins primarily as a result of lower sales prices in the second quarter of 2015 as compared to the prior-year period, and costs related to several maintenance turnarounds completed during the second quarter of 2015.

For the six months ended June 30, 2015, net income attributable to Westlake Chemical Corporation was $351.4 million, or $2.64 per diluted share, on net sales of $2.3 billion. This represents an increase in net income attributable to Westlake Chemical Corporation of $23.9 million, or $0.20 per diluted share, from the six months ended June 30, 2014 net income attributable to Westlake Chemical Corporation of $327.5 million, or $2.44 per diluted share, on net sales of $2.0 billion. Net income attributable to Westlake Chemical Corporation for the six months ended June 30, 2015 included a net pre-tax gain of $15.5 million, or $0.13 per diluted share, related to the bargain purchase gain from the acquisition of a controlling interest in Huasu and the partial impairment of an equity method investment. Net sales for the six months ended June 30, 2015increased by $262.2 million compared to the prior-year period, primarily due to sales contributed by Vinnolit, higher sales volumes for ethylene, PVC resin and caustic soda, partially offset by lower sales prices for all our major products. Income from operations was $524.7 million for the six months ended June 30, 2015 as compared to $514.8 million for the six months ended June 30, 2014, an increase mainly attributable to improved vinyls integrated product margins, primarily driven by 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, and the contribution from Vinnolit, partially offset by lower olefins integrated product margins mainly as a result of lower sales prices as compared to the prior-year period. Sales prices in the first six months of 2015 were negatively impacted by the significant decline in crude oil prices.

RESULTS OF OPERATIONS

Second Quarter 2015 Compared with Second Quarter 2014

Net Sales. Net sales increased by $186.4 million, or 18.7%, to $1.2 billion in the second quarter of 2015 from $998.6 million in the second quarter of 2014, primarily attributable 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. Average sales prices for the second quarter of 2015 decreased by 24.0% as compared to the second quarter of 2014. Sales prices in the second quarter of 2015 were negatively impacted by the lower crude oil prices as compared to the prior-year period. Overall sales volumes increased by 42.6% as compared to the second quarter of 2014.

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Gross Profit. Gross profit margin percentage decreased to 29.8% for the second quarter of 2015 from 30.6% for the second quarter of 2014. The second quarter 2015 gross profit benefited from lower average feedstock costs. However, this increase was more than offset by lower sales prices for our major products as sales prices decreased an average of 24.0% for the second quarter of 2015 as compared to the second quarter of 2014.

Selling, General and Administrative Expenses. Selling, general and administrative expenses for the second quarter of 2015 of $57.8 millionincreased by $18.6 million as compared to the second quarter of 2014, mainly due to general and administrative costs incurred by Vinnolit for the second quarter of 2015 and an increase in consulting and professional fees.

Interest Expense. Interest expense decreased by $0.5 million to $9.0 million in the second quarter of 2015 from $9.5 million in the second 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, Net. Other income, net increased by $17.5 million to $22.1 million in the second quarter of 2015 from $4.6 million in the second quarter of 2014 mainly due to the bargain purchase gain from the acquisition of a controlling interest in Huasu, net of related expenses, of approximately $20.4 million.

Income Taxes. The effective income tax rate was 31.9% for the second quarter of 2015. The effective income tax rate for the second 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 non-recognition of tax related to the bargain purchase of a controlling interest in Huasu and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 35.3% for the second quarter of 2014. The effective income tax rate for the second quarter of 2014 was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, mostly offset by the domestic manufacturing deduction.

Olefins Segment

Net Sales. Net sales decreased by $78.2 million, or 11.2%, to $620.9 million in the second quarter of 2015 from $699.1 million in the second quarter of 2014, primarily due to lower sales prices for our major products, partially offset by higher sales volumes for ethylene and polyethylene as compared to the prior-year period. Average sales prices for the Olefins segment decreased by 29.4% in the second quarter of 2015 as compared to the second quarter of 2014. Average sales volumes for the Olefins segment increased by 18.2% in the second quarter of 2015 as compared to the second quarter of 2014.

Income from Operations. Income from operations decreased by $17.8 million, or 7.5%, to $220.9 million in the second quarter of 2015 from $238.7 million in the second quarter of 2014. This decrease was mainly attributable to lower olefins integrated product margins primarily as a result of lower sales prices and costs incurred related to several polyethylene maintenance turnarounds completed in the second quarter of 2015, partially offset by higher polyethylene sales volume and lower feedstock and energy costs in the second quarter of 2015 as compared to the prior-year period.

Vinyls Segment

Net Sales. Net sales increased by $264.6 million, or 88.3%, to $564.1 million in the second quarter of 2015 from $299.5 million in the second quarter of 2014. This increase was mainly attributable to sales contributed by Vinnolit and higher domestic sales volumes for PVC resin and caustic soda, partially offset by lower sales prices for our major products. Average sales prices for the Vinyls segment decreased by 11.3% in the second quarter of 2015 as compared to the second quarter of 2014. Average sales volumes for the Vinyls segment increased by 99.7% in the second quarter of 2015 as compared to the second quarter of 2014, primarily attributable to sales contributed by Vinnolit.

Income (Loss) from Operations. Income from operations increased by $49.9 million to $88.0 million in the second quarter of 2015 from $38.1 million in the second quarter of 2014. This increase was primarily driven by higher vinyls integrated product margins in the second quarter of 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, as compared to the prior-year period. In addition, second quarter 2015 income from operations benefited from higher caustic soda sales volume, primarily attributable to higher production rates at our Geismar chlor-alkali plant, and the contribution from Vinnolit. The increase in second quarter 2015 income from operations was partially offset by lower sales prices for our major products, as compared to the second quarter of 2014, and costs and reduced sales volume in Europe related to a maintenance turnaround and ethylene shortage. Second quarter 2014 income from operations was negatively impacted by significantly higher propane costs and the lost sales, lower production rates, unabsorbed fixed manufacturing costs 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.

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Six Months Ended June 30, 2015 Compared with Six Months Ended June 30, 2014

Net Sales. Net sales increased by $262.2 million, or 12.9%, to $2.3 billion for the six months ended June 30, 2015 from $2.0 billion for the six months ended June 30, 2014, primarily attributable to sales contributed by Vinnolit, higher sales volumes for ethylene, PVC resin and caustic soda, partially offset by lower sales prices for all our major products. Average sales prices for the six months ended June 30, 2015 decreased by 23.3% as compared to the six months ended June 30, 2014. Sales prices in the first six months of 2015 were negatively impacted by the significant decline in crude oil prices. Overall sales volumes for the six months ended June 30, 2015 increased by 36.2% as compared to the six months ended June 30, 2014.

Gross Profit. Gross profit margin percentage of 27.9% for the six months ended June 30, 2015decreased from the 29.3% gross profit margin percentage for the six months ended June 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 23.3% for the six months ended June 30, 2015 as compared to the prior-year period. In addition, gross profit for the six months ended June 30, 2015 was negatively impacted by lost sales, lower production rates and costs associated with the maintenance turnaround at our Geismar facility. The decrease in gross profit for the six months ended June 30, 2015 was partially offset by lower average feedstock 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 six months ended June 30, 2015increased by $35.0 million as compared to the six months ended June 30, 2014, mainly attributable to general and administrative costs incurred by Vinnolit for the six months ended June 30, 2015, an increase in payroll and related labor costs, including incentive compensation, and an increase in consulting and professional fees.

Interest Expense. Interest expense decreased by $0.2 million to $18.5 million for the six months ended June 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 $24.1 million to $31.2 million for the six months ended June 30, 2015 from $7.1 million for the six months ended June 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, the gain from the sales of equity securities and dividends received from cost method investments, partially offset by the partial impairment of an equity method investment.

Income Taxes. The effective income tax rate was 32.9% for the six months ended June 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 and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 34.9% for the six months ended June 30, 2014. The effective income tax rate for the 2014 period was below the U.S. federal statutory rate of 35.0% primarily due to state tax credits and the domestic manufacturing deduction, mostly offset by state income taxes.

Olefins Segment

Net Sales. Net sales decreased by $217.9 million, or 15.3%, to $1.2 billion for the six months ended June 30, 2015 from $1.4 billion for the six months ended June 30, 2014, mainly due to lower sales prices for our major products, partially offset by higher sales volumes for ethylene and polyethylene as compared to the prior-year period. Average sales prices for the Olefins segment decreased by 28.4% for the six months ended June 30, 2015 as compared to the six months ended June 30, 2014. Average sales volumes for the Olefins segment increased by 13.1% for the six months ended June 30, 2015 as compared to the six months ended June 30, 2014.

Income from Operations. Income from operations decreased by $99.0 million, or 19.4%, to $412.0 million for the six months ended June 30, 2015 from $511.0 million for the six months ended June 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 ethylene and polyethylene sales volumes and lower feedstock and energy costs for the six months ended June 30, 2015 as compared to the prior-year period. Trading activity for the six months ended June 30, 2015 resulted in a gain of $4.8 million as compared to a loss of $0.4 million for the prior-year period.

Vinyls Segment

Net Sales. Net sales increased by $480.2 million, or 79.5%, to $1.1 billion for the six months ended June 30, 2015 from $604.4 million for the six months ended June 30, 2014. This increase was primarily attributable to sales contributed by Vinnolit

33

and higher sales volumes for PVC resin and caustic soda, partially offset by lower sales prices for our major products and lower sales volume for ethylene co-products. Ethylene co-products sales volumes were lower for the six months ended June 30, 2015, mainly due to the change to ethane feedstock currently utilized at OpCo's Calvert City ethylene plant following the completion of the feedstock conversion and ethylene expansion project. Average sales prices for the Vinyls segment decreased by 11.2% for the six months ended June 30, 2015 as compared to the six months ended June 30, 2014. Average sales volumes for the Vinyls segment increased by 90.6% for the six months ended June 30, 2015 as compared to the six months ended June 30, 2014, primarily related to sales contributed by Vinnolit.

Income from Operations. Income from operations increased by $118.1 million to $135.1 million for the six months ended June 30, 2015 from $17.0 million for the six months ended June 30, 2014. This increase was primarily driven by higher vinyls integrated product margins for the six months ended June 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 six months ended June 30, 2015 was partially offset by lost sales, lower production rates and costs associated with the maintenance turnaround at our Geismar facility and lower sales prices for our major products. Income from operations for the six months ended June 30, 2014 was negatively impacted by lost sales, lower production rates, unabsorbed fixed manufacturing costs 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 SIX MONTHS ENDED JUNE 30, 2015 AND 2014

Cash Flows

Operating Activities

Operating activities provided cash of $435.4 million in the first six months of 2015 compared to cash provided of $432.2 million in the first six months of 2014. The $3.2 millionincrease in cash flows from operating activities was mainly due to an increase in income from operations and an increase in depreciation and amortization, partially offset by an increase in the use of cash for working capital purposes. Income from operations increased by $9.9 million in the first six months of 2015 primarily due to higher vinyls integrated product margins, mainly driven by lower feedstock costs, increased production at our Calvert City facilities and higher production rates at our Geismar chlor-alkali plant, and the contribution from Vinnolit. This increase was partially offset by lower olefins integrated product margins mostly due to lower sales prices, as compared to the prior-year period. 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, used cash of $25.9 million in the first six months of 2015, compared to $6.9 million of cash used in the first six months of 2014, an unfavorable change of $19.0 million. The change was mainly due to a decrease in current liabilities (accounts payable and accrued liabilities), partially offset by lower inventory mainly as a result of lower product prices during the 2015 period, as compared to the prior-year period.

Investing Activities

Net cash used for investing activities during the first six months of 2015 was $174.3 million as compared to net cash provided for investing activities of $7.5 million in the first six months of 2014. Capital expenditures were $203.9 million in the first six months of 2015 compared to $216.9 million in the first six months of 2014, a decrease mainly attributable to the completion of the feedstock conversion and ethylene expansion project and PVC plant expansion project at our Calvert City site in the second quarter of 2014. Capital expenditures in the first six months of 2015 were mainly 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 six 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 six 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. We also received aggregate proceeds of $15.0 million from the sales of our investments in the first six months of 2015. The activity during the first six months of 2014 was primarily related to the purchases of securities and the receipt of proceeds from the sales and maturities of our investments.

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Financing Activities

Net cash used by financing activities during the first six months of 2015 was $113.1 million as compared to net cash used of $25.0 million in the first six months of 2014. The activity during the first six months of 2015 was primarily related to the $43.9 million payment of cash dividends, $7.2 million payment of cash distributions to noncontrolling interests and the $62.8 million of cash used for the repurchases of shares of our common stock, partially offset by proceeds of $0.8 million from the exercise of stock options. In addition, we repaid $4.3 million of short-term notes payable to banks, partially offset by $2.4 million of proceeds received from the issuance of the notes payable. The activity during the first six months of 2014 was mainly related to the $33.6 million payment of cash dividends, partially offset by proceeds from the exercise of stock options.

LIQUIDITY AND CAPITAL RESOURCES

Liquidity and Financing Arrangements

Our principal sources of liquidity are from cash and cash equivalents, 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 upgrade and expand the capacity of its Petro 1 ethylene unit at our Lake Charles site during the first half 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 June 30, 2015, OpCo had incurred a total cost of approximately $114.4 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 June 30, 2015, we repurchased 850,457 shares of our common stock for an aggregate purchase price of approximately $60.8 million under the 2014 Program. As of June 30, 2015, we had repurchased 865,034 shares of our common stock for an aggregate purchase price of approximately $61.7 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.

Cash and Cash Equivalents

As of June 30, 2015, our cash and cash equivalents totaled $1.0 billion. In addition, we have a revolving credit facility available to supplement cash if needed, as described under "Debt" below.

Debt

As of June 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 June 30, 2015, debt outstanding under the tax-exempt waste disposal revenue bonds bore interest at a variable rate. As of June 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.

35

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 June 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 June 30, 2015, we had outstanding letters of credit totaling $29.7 million and borrowing availability of $370.3 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, 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 June 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

36

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' 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 June 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 June 30, 2015, outstanding borrowings under the credit facility totaled $113.9 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 eliminate 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;

37

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

• production capacities;

• currency devaluation;

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

• our ability to meet our liquidity needs;

• our intended quarterly dividends;

• 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;

• 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.

38

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 June 30, 2015, a hypothetical $0.10 increase in the price of a gallon of ethane would have increased our income before taxes by $20.3 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 June 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 June 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 June 30, 2015 was 0.15%. 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 June 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 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 June 30, 2015 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

39

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 June 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)
April 2015	250	$	77.77	—	$	249,150,000
May 2015	218,850	$	71.00	218,178	$	232,865,000
June 2015	632,279	$	71.67	632,279	$	188,346,000
	851,379	$	71.50	850,457

_____________

(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 June 30, 2015, 865,034 shares of common stock had been acquired at an aggregate purchase price of $61.7 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.

40

Item 6. Exhibits

Exhibit No.
10.1	Senior Unsecured Revolving Credit Agreement by and among Westlake Chemical Partners GP LLC and Westlake Chemical Finance Corporation, dated as of April 29, 2015 (incorporated by reference to Exhibit 10.1 to Westlake Chemical Partners LP's Current Report on Form 8-K filed on April 30, 2015, File No. 1-36567)
10.2	Form of Stock Option Award Letter for 2015 Executive Officer Awards (incorporated by reference to Exhibit 10.3 to Westlake Chemical Corporation's Quarterly Report on Form 10-Q for the quarter ended March 31, 2015, File No. 1-32260)
10.3	Form of Restricted Stock Units Award Letter for 2015 Executive Officer Awards (incorporated by reference to Exhibit 10.4 to Westlake Chemical Corporation's Quarterly Report on Form 10-Q for the quarter ended March 31, 2015, File No. 1-32260)
10.4	Form of Long-Term Cash Performance Award Letter for 2015 Executive Officer Awards (incorporated by reference to Exhibit 10.5 to Westlake Chemical Corporation's Quarterly Report on Form 10-Q for the quarter ended March 31, 2015, File No. 1-32260)
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.

41

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:	August 5, 2015	By:	/S/    ALBERT CHAO
			Albert Chao
			President and Chief Executive Officer (Principal Executive Officer)
Date:	August 5, 2015	By:	/S/    M. STEVEN BENDER
			M. Steven Bender
			Senior Vice President, Chief Financial Officer and Treasurer (Principal Financial Officer)

42

EXHIBIT INDEX

Exhibit No.	Exhibit
10.1	Senior Unsecured Revolving Credit Agreement by and among Westlake Chemical Partners GP LLC and Westlake Chemical Finance Corporation, dated as of April 29, 2015 (incorporated by reference to Exhibit 10.1 to Westlake Chemical Partners LP's Current Report on Form 8-K filed on April 30, 2015, File No. 1-36567)
10.2	Form of Stock Option Award Letter for 2015 Executive Officer Awards (incorporated by reference to Exhibit 10.3 to Westlake Chemical Corporation's Quarterly Report on Form 10-Q for the quarter ended March 31, 2015, File No. 1-32260)
10.3	Form of Restricted Stock Units Award Letter for 2015 Executive Officer Awards (incorporated by reference to Exhibit 10.4 to Westlake Chemical Corporation's Quarterly Report on Form 10-Q for the quarter ended March 31, 2015, File No. 1-32260)
10.4	Form of Long-Term Cash Performance Award Letter for 2015 Executive Officer Awards (incorporated by reference to Exhibit 10.5 to Westlake Chemical Corporation's Quarterly Report on Form 10-Q for the quarter ended March 31, 2015, File No. 1-32260)
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.

43

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:	August 5, 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:	August 5, 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 June 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:	August 5, 2015	/S/    ALBERT CHAO
		Albert Chao
		President and Chief Executive Officer (Principal Executive Officer)
Date:	August 5, 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 June 30, 2015

FINANCIAL STATEMENTS

WESTLAKE CHEMICAL OPCO LP

BALANCE SHEETS

(Unaudited)

	June 30, 2015		December 31, 2014
	(in thousands of dollars)
ASSETS
Current assets
Cash and cash equivalents	$	133,890	$	131,545
Accounts receivable, net—Westlake Chemical Corporation ("Westlake")	35,882		18,529
Accounts receivable, net—third parties	22,075		37,520
Inventories	3,856		6,634
Prepaid expenses and other current assets	30		212
Total current assets	195,733		194,440
Property, plant and equipment, net	914,270		842,057
Other assets, net
Goodwill	5,814		5,814
Deferred charges and other assets, net	44,204		51,919
Total other assets, net	50,018		57,733
Total assets	$	1,160,021	$	1,094,230
LIABILITIES
Current liabilities
Accounts payable—Westlake	$	13,921	$	5,332
Accounts payable—third parties	22,418		12,348
Accrued liabilities	16,441		11,225
Total current liabilities	52,780		28,905
Long-term debt payable to Westlake	145,651		227,638
Deferred income taxes	1,614		1,848
Other liabilities	—		—
Total liabilities	200,045		258,391
Commitments and contingencies (Notes 8 and 13)
EQUITY
Limited partners interest—Westlake	492,443		504,854
Limited partner interest—Westlake Chemical Partners LP	467,533		330,985
Total equity	959,976		835,839
Total liabilities and equity	$	1,160,021	$	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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
				Predecessor						Predecessor
	(in thousands of dollars)
Revenue
Net sales—Westlake	$	204,669		$	415,033		$	413,582		$	798,960
Net co-product, ethylene and feedstock sales—third   parties	47,036			109,102			96,514			285,189
Total net sales	251,705			524,135			510,096			1,084,149
Cost of sales	157,177			277,589			319,341			605,289
Gross profit	94,528			246,546			190,755			478,860
Selling, general and administrative expenses	5,191			6,165			10,237			13,943
Income from operations	89,337			240,381			180,518			464,917
Other income (expense)
Interest expense—Westlake	(856		)	(4,105		)	(2,232		)	(7,696		)
Other income, net	34			1,397			39			2,649
Income before income taxes	88,515			237,673			178,325			459,870
(Benefit from) provision for income taxes	(41		)	83,829			426			162,152
Net income	$	88,556		$	153,844		$	177,899		$	297,718

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)
Balance as of December 31, 2013	$	455,432		$	—		$	—		$	455,432
Net income	297,718			—			—			297,718
Net distributions to Westlake	(376,613		)	—			—			(376,613		)
Balance as of June 30, 2014	$	376,537		$	—		$	—		$	376,537
Balance as of December 31, 2014	$	—		$	504,854		$	330,985		$	835,839
Net income	—			156,690			21,209			177,899
Capital contribution from Westlake Chemical Partners   LP for additional interest	—			—			135,341			135,341
Quarterly distributions	—			(169,101		)	(20,002		)	(189,103		)
Balance as of June 30, 2015	$	—		$	492,443		$	467,533		$	959,976

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

3

WESTLAKE CHEMICAL OPCO LP

COMBINED STATEMENTS OF CASH FLOWS

(Unaudited)

	Six Months Ended June 30,
	2015			2014
				Predecessor
	(in thousands of dollars)
Cash flows from operating activities
Net income	$	177,899		$	297,718
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	40,195			39,282
Provision for doubtful accounts	170			65
Loss from disposition of fixed assets	124			1,238
Deferred income taxes	(234		)	6,813
Income from equity method investment, net of dividends	—			215
Changes in operating assets and liabilities
Accounts receivable—third parties	15,275			9,258
Net accounts receivable—Westlake	(8,764		)	—
Inventories	2,778			18,996
Prepaid expenses and other current assets	182			212
Accounts payable	4,673			(2,583		)
Accrued and other liabilities	2,019			208
Other, net	(709		)	7,499
Net cash provided by operating activities	233,608			378,921
Cash flows from investing activities
Additions to property, plant and equipment	(95,514		)	(106,191		)
Settlements of derivative instruments	—			(290		)
Net cash used for investing activities	(95,514		)	(106,481		)
Cash flows from financing activities
Proceeds from debt payable to Westlake	53,354			104,173
Repayment of debt payable to Westlake	(135,341		)	—
Capital contribution from Westlake Chemical Partners LP for additional interest	135,341			—
Quarterly distributions	(189,103		)	—
Net distributions to Westlake prior to initial public offering	—			(376,613		)
Net cash used for financing activities	(135,749		)	(272,440		)
Net increase in cash and cash equivalents	2,345			—
Cash and cash equivalents at beginning of period	131,545			—
Cash and cash equivalents at end of period	$	133,890		$	—

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 effective April 1, 2015. 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, as filed with the SEC on February 25, 2015. These combined 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 presented for the periods prior to the IPO on August 4, 2014 consists of the Predecessor's combined results of operations, changes in equity and cash flows. 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.

In the opinion of management, the accompanying unaudited combined financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Predecessor's combined financial statements for the three and six months ended June 30, 2014 and OpCo's financial statements as of June 30, 2015 and December 31, 2014, and for the three and six months ended June 30, 2015.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 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 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

5

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

"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.

2. Financial Instruments

Cash Equivalents

OpCo had $75,029 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 June 30, 2015 and December 31, 2014, respectively. OpCo's investments in held-to-maturity securities are held at amortized cost, which approximates fair value.

3. Accounts Receivable—Third Parties

Accounts receivable—third parties consist of the following:

	June 30, 2015			December 31, 2014
Trade customers	$	22,245		$	37,514
Allowance for doubtful accounts	(170		)	—
	22,075			37,514
Other	—			6
Accounts receivable, net—third parties	$	22,075		$	37,520

4. Inventories

Inventories consist of the following:

	June 30, 2015		December 31, 2014
Finished products	$	3,596	$	6,257
Feedstock, additives and chemicals	260		377
Inventories	$	3,856	$	6,634

5. Property, Plant and Equipment

As of June 30, 2015, OpCo had property, plant and equipment, net totaling $914,270. 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

6

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

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 $16,182 and $15,720 is included in cost of sales in the combined statements of operations for the three months ended June 30, 2015 and 2014, respectively. Depreciation expense on property, plant and equipment of $31,775 and $30,204 is included in cost of sales in the combined statements of operations for the six months ended June 30, 2015 and 2014, respectively.

6. Other Assets

Amortization expense on other assets of $4,210 and $4,548 is included in the combined statements of operations for the three months ended June 30, 2015 and 2014, respectively. Amortization expense on other assets of $8,420 and $9,078 is included in the combined statements of operations for the six months ended June 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.

Sales to related parties were as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
			Predecessor				Predecessor
Net sales—Westlake	$	204,669	$	415,033	$	413,582	$	798,960

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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
			Predecessor				Predecessor
Feedstock purchased from Westlake and included in cost   of sales	$	76,013	$	—	$	156,832	$	—
Other charges from Westlake and included in cost of   sales	19,595		16,534		33,491		33,122
Total	$	95,608	$	16,534	$	190,323	$	33,122

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's finance, legal, information technology, human resources, communication, ethics and compliance, and other administrative functions.

7

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

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 allocation 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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
			Predecessor				Predecessor
Services received from Westlake and included in selling,   general and administrative expenses	$	4,971	$	5,142	$	10,119	$	11,618

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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
			Predecessor				Predecessor
Goods and services purchased from Westlake and   capitalized as assets	$	975	$	1,245	$	1,937	$	3,075

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:

	June 30, 2015			December 31, 2014
Accounts receivable, net—Westlake	$	35,882		$	18,529
Accounts payable—Westlake	(13,921		)	(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 June 30, 2015 and 2014 were $856 and $4,105, respectively, and for the six months ended June 30, 2015 and 2014 were $2,232 and $7,696, respectively, and are reflected as a component of other income (expense) in the combined statement of operations. Interest capitalized as a component of property, plant and equipment on related party debt was $895 for the three months ended June 30, 2015 and $2,110 for the six months ended June 30, 2015. At June 30, 2015 and December 31, 2014, accrued interest on related party debt was $1,751 and $2,403, respectively, and is reflected as a component of accrued liabilities in the balance sheet.

8

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

Debt payable to related parties was as follows:

	June 30, 2015		December 31, 2014
Long-term debt payable to Westlake	$	145,651	$	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 June 30, 2015 and December 31, 2014, Westlake had outstanding letters of credit totaling $29,670 and $31,392 under its revolving credit facility and $754,000 and $754,000 outstanding under its senior notes (less the unamortized discount of $833 and $921), 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:

	June 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 LIBOR plus 3.0%, original scheduled maturity of   August 4, 2019)	113,876		60,522
	$	145,651	$	227,638

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 six months ended June 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 six months ended June 30, 2015 were used to fund capital expenditures at the OpCo's ethylene plants.

As of June 30, 2015, OpCo was in compliance with all of the covenants under the August 2013 Promissory Notes 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.

9

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

There were no assets or liabilities accounted for at fair value on a recurring basis as of June 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 six months ended June 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 June 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 OpCo's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of OpCo's long-term debt include the selection of an appropriate discount rate.

	June 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	113,876		128,769		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 consolidated U.S. federal and state income tax returns. Amounts presented in the combined financial statements 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 financial statements.

The effective income tax rates were 0.0% and 0.2% for the three and six months ended June 30, 2015, respectively. The effective income tax rates for the three and six months ended June 30, 2015 are not comparable to the effective income tax rates for the prior-year comparative periods as OpCo is not subject to federal income taxes subsequent to the IPO. The effective income tax rates of the Predecessor were 35.3% and 35.3% for the three and six months ended June 30, 2014, respectively. The effective income tax rates for the three and six months ended June 30, 2014 were 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.

11.Supplemental Information

Non-cash Operating Activity

The Predecessor settled $4,099 and $7,441 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 six months ended June 30, 2014, respectively.

Non-cash Investing Activity

The change in capital expenditure accrual reducing additions to property, plant and equipment was $8,594 for the six months ended June 30, 2015. The change in capital expenditure accrual increasing additions to property, plant and equipment was $2,062 for the six months ended June 30, 2014.

12. Major Customer and Concentration of Credit Risk

During the three months ended June 30, 2015 and 2014, Westlake accounted for approximately 81.3% and 79.2%, respectively, of OpCo's and the Predecessor's net sales. During the six months ended June 30, 2015 and 2014, Westlake accounted for approximately 81.1% and 73.7%, respectively, of OpCo's and the Predecessor's net sales.

10

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

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 and secondment 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 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

11

WESTLAKE CHEMICAL OPCO LP

NOTES TO COMBINED FINANCIAL STATEMENTS - Continued

(Unaudited)

(in thousands of dollars)

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.

14. Subsequent Events

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

12

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Earnings per Share (Tables)

6 Months Ended

Jun. 30, 2015

Earnings Per Share [Abstract]

Schedule Of Net Income Attributable To Common Stockholders

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Net income attributable to    Westlake Chemical Corporation	$	205,095		$	169,443		$	351,437		$	327,475
Less:
Net income attributable to participating securities	(253		)	(360		)	(457		)	(746		)
Net income attributable to common shareholders	$	204,842		$	169,083		$	350,980		$	326,729

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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Weighted average common shares—basic	132,538,123		133,223,705		132,625,857		133,148,398
Plus incremental shares from:
Assumed exercise of options	506,852		544,185		498,840		542,438
Weighted average common shares—diluted	133,044,975		133,767,890		133,124,697		133,690,836
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.55	$	1.27	$	2.65	$	2.45
Diluted	$	1.54	$	1.26	$	2.64	$	2.44

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Stockholders' Equity (Changes in Stockholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			$ 3,201,888	$ 2,418,603
Net income	$ 210,061	$ 169,443	360,468	327,475
Pension and other post- retirement benefits liability			752	255
Foreign currency translation adjustments			(41,826)	(90)
Net unrealized holding gains on investments			583	2,319
Common stock repurchased			(62,804)
Shares issued—stock- based compensation			831	4,187
Stock-based compensation, net of tax on stock options exercised			6,800	8,947
Dividends paid			(43,896)	(33,623)
Distributions to noncontrolling interests			(7,218)
Noncontrolling interest in acquired business			1,597
Amount, ending balance	3,417,175	2,728,073	3,417,175	2,728,073
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			(62,804)
Shares issued—stock- based compensation			704	1,039
Amount, ending balance	(158,472)	(45,181)	(158,472)	(45,181)
Additional Paid-in Capital [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			530,441	511,432
Shares issued—stock- based compensation			127	3,147
Stock-based compensation, net of tax on stock options exercised			6,800	8,947
Amount, ending balance	537,368	523,526	537,368	523,526
Retained Earnings [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			2,555,528	1,954,661
Net income			351,437	327,475
Dividends paid			(43,896)	(33,623)
Amount, ending balance	2,863,069	2,248,513	2,863,069	2,248,513
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			752	255
Foreign currency translation adjustments			(41,826)	(90)
Net unrealized holding gains on investments			583	2,319
Amount, ending balance	(119,924)	$ (132)	(119,924)	$ (132)
Noncontrolling Interest [Member]
Schedule of Capitalization, Equity [Line Items]
Amount, beginning balance			290,377
Net income			9,031
Distributions to noncontrolling interests			(7,218)
Noncontrolling interest in acquired business			1,597
Amount, ending balance	$ 293,787		$ 293,787

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Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished products	$ 280,317	$ 300,909
Feedstock, additives and chemicals	134,369	158,635
Materials and supplies	71,611	66,232
Inventories	$ 486,297	$ 525,776

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Acquisition (Narrative) (Details) - Jun. 01, 2015 $ in Thousands, lb in Millions	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

Stockholders' Equity (Changes in AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 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			(38,926)	2,986
Amounts reclassified from accumulated other comprehensive loss			(1,565)	(502)
Other comprehensive income (loss)	$ 17,738	$ 1,650	(40,491)	2,484
Accumulated other comprehensive income (loss), ending balance	(119,924)	(132)	(119,924)	(132)
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			(115)	(20)
Amounts reclassified from accumulated other comprehensive loss			867	275
Other comprehensive income (loss)			752	255
Accumulated other comprehensive income (loss), ending balance	(22,690)	(6,441)	(22,690)	(6,441)
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			(41,826)	(90)
Amounts reclassified from accumulated other comprehensive loss			0	0
Other comprehensive income (loss)			(41,826)	(90)
Accumulated other comprehensive income (loss), ending balance	(98,050)	3,814	(98,050)	3,814
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			3,015	3,096
Amounts reclassified from accumulated other comprehensive loss			(2,432)	(777)
Other comprehensive income (loss)			583	2,319
Accumulated other comprehensive income (loss), ending balance	$ 816	$ 2,495	$ 816	$ 2,495

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Guarantor Disclosures (Additional Information) (Detail) - Jun. 30, 2015 - USD ($) $ in Thousands	Total
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

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Financial Instruments (Available-for-sale Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 3,802		$ 3,802		$ 15,050
Gross Unrealized Gains	1,272		1,272		364
Gross Unrealized Losses	0		0		0
Fair Value	5,074		5,074		15,414
Net unrealized gains on available-for-sale securities	816		816		233
Income tax on gains from available-for-sale securities	456		456		131
Proceeds from sales and maturities of securities	15,037	$ 311,926	15,037	$ 342,045
Gross realized gains	3,795	1,298	3,795	1,311
Gross realized losses	0	$ (61)	0	$ (99)
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	3,802		3,802		15,050
Gross Unrealized Gains	1,272		1,272		364
Gross Unrealized Losses	0		0		0
Fair Value	$ 5,074		$ 5,074		$ 15,414

XML

Accounts and Notes Payable (Tables)

6 Months Ended

Jun. 30, 2015

Accounts and Notes Payable [Abstract]

Schedule of Accounts Payable and Accrued Liabilities

	June 30, 2015		December 31, 2014
Accounts payable	$	263,803	$	261,062
Notes payable to banks	19,175		—
Accounts and notes payable	$	282,978	$	261,062

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Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 1,026,569	$ 880,601	$ 876,067	$ 461,301
Accounts receivable, net	600,722	560,666
Inventories	486,297	525,776
Prepaid expenses and other current assets	23,018	11,807
Deferred income taxes	29,634	32,437
Total current assets	2,166,240	2,011,287
Property, plant and equipment, net	2,855,508	2,757,557
Equity investments	37,746	61,305
Other assets, net	351,516	383,841
Total assets	5,411,010	5,213,990
Accounts payable		261,062
Accounts and notes payable	282,978	261,062
Accrued liabilities	251,680	276,118
Total current liabilities	534,658	537,180
Long-term debt	764,056	763,997
Deferred income taxes	532,344	536,066
Other liabilities	162,777	174,859
Total liabilities	1,993,835	2,012,102
Total Westlake Chemical Corporation stockholders' equity	3,123,388	2,911,511
Noncontrolling interests	293,787	290,377
Total equity	3,417,175	3,201,888	2,728,073	2,418,603
Total liabilities and equity	5,411,010	5,213,990
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	756,385	655,947	833,650	420,948
Accounts receivable, net	13,335	8,451
Inventories	0	0
Prepaid expenses and other current assets	136	172
Deferred income taxes	409	409
Total current assets	770,265	664,979
Property, plant and equipment, net	0	0
Equity investments	4,690,426	4,033,378
Other assets, net	18,920	30,543
Total assets	5,479,611	4,728,900
Accounts payable		1,055,527
Accounts and notes payable	1,594,555
Accrued liabilities	8,501	8,754
Total current liabilities	1,603,056	1,064,281
Long-term debt	753,167	753,108
Deferred income taxes	0	0
Other liabilities	0	0
Total liabilities	2,356,223	1,817,389
Total Westlake Chemical Corporation stockholders' equity	3,123,388	2,911,511
Noncontrolling interests	0	0
Total equity	3,123,388	2,911,511
Total liabilities and equity	5,479,611	4,728,900
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	3,923	3,057	8,819	6,227
Accounts receivable, net	1,995,787	1,454,709
Inventories	376,750	414,975
Prepaid expenses and other current assets	20,981	9,485
Deferred income taxes	29,832	29,832
Total current assets	2,427,273	1,912,058
Property, plant and equipment, net	1,520,734	1,477,515
Equity investments	1,228,964	1,237,080
Other assets, net	300,172	387,325
Total assets	5,477,143	5,013,978
Accounts payable		160,834
Accounts and notes payable	145,719
Accrued liabilities	173,112	203,608
Total current liabilities	318,831	364,442
Long-term debt	10,889	10,889
Deferred income taxes	498,993	497,919
Other liabilities	39,553	43,452
Total liabilities	868,266	916,702
Total Westlake Chemical Corporation stockholders' equity	4,608,877	4,097,276
Noncontrolling interests	0	0
Total equity	4,608,877	4,097,276
Total liabilities and equity	5,477,143	5,013,978
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	133,890	131,545	0	0
Accounts receivable, net	57,957	56,049
Inventories	3,856	6,634
Prepaid expenses and other current assets	30	212
Deferred income taxes	0	0
Total current assets	195,733	194,440
Property, plant and equipment, net	914,270	842,057
Equity investments	0	0
Other assets, net	50,018	57,733
Total assets	1,160,021	1,094,230
Accounts payable		17,680
Accounts and notes payable	36,339
Accrued liabilities	16,441	11,225
Total current liabilities	52,780	28,905
Long-term debt	145,651	227,638
Deferred income taxes	1,614	1,848
Other liabilities	0	0
Total liabilities	200,045	258,391
Total Westlake Chemical Corporation stockholders' equity	959,976	835,839
Noncontrolling interests	0	0
Total equity	959,976	835,839
Total liabilities and equity	1,160,021	1,094,230
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	132,371	90,052	33,598	34,126
Accounts receivable, net	144,560	135,133
Inventories	105,691	104,167
Prepaid expenses and other current assets	4,132	1,938
Deferred income taxes	279	2,196
Total current assets	387,033	333,486
Property, plant and equipment, net	420,504	437,985
Equity investments	467,530	352,550
Other assets, net	133,840	141,948
Total assets	1,408,907	1,265,969
Accounts payable		95,856
Accounts and notes payable	104,954
Accrued liabilities	69,101	77,372
Total current liabilities	174,055	173,228
Long-term debt	0	0
Deferred income taxes	37,520	42,369
Other liabilities	123,224	131,407
Total liabilities	334,799	347,004
Total Westlake Chemical Corporation stockholders' equity	780,321	628,588
Noncontrolling interests	293,787	290,377
Total equity	1,074,108	918,965
Total liabilities and equity	1,408,907	1,265,969
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts receivable, net	(1,610,917)	(1,093,676)
Inventories	0	0
Prepaid expenses and other current assets	(2,261)	0
Deferred income taxes	(886)	0
Total current assets	(1,614,064)	(1,093,676)
Property, plant and equipment, net	0	0
Equity investments	(6,349,174)	(5,561,703)
Other assets, net	(151,434)	(233,708)
Total assets	(8,114,672)	(6,889,087)
Accounts payable		(1,068,835)
Accounts and notes payable	(1,598,589)
Accrued liabilities	(15,475)	(24,841)
Total current liabilities	(1,614,064)	(1,093,676)
Long-term debt	(145,651)	(227,638)
Deferred income taxes	(5,783)	(6,070)
Other liabilities	0	0
Total liabilities	(1,765,498)	(1,327,384)
Total Westlake Chemical Corporation stockholders' equity	(6,349,174)	(5,561,703)
Noncontrolling interests	0	0
Total equity	(6,349,174)	(5,561,703)
Total liabilities and equity	$ (8,114,672)	$ (6,889,087)

XML

Commitments and Contingencies (Additional Information) (Detail) - USD ($) $ in Thousands	12 Months Ended	95 Months Ended
	Dec. 31, 2014	Jun. 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

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Pension and Post-Retirement Benefit Costs (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
United States Pension Plan of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 84	$ 29	$ 167
Interest cost	489	576	1,032	1,170
Expected return on plan assets	(705)	(777)	(1,524)	(1,586)
Amortization of prior service cost	0	74	0	148
Amortization of net loss	318	70	609	134
Net periodic benefit cost	(103)	(27)	(146)	(33)
Foreign Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	414		835
Interest cost	525		1,061
Expected return on plan assets	0		0
Amortization of prior service cost	0		0
Amortization of net loss	261		526
Net periodic benefit cost	(1,200)		(2,422)
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	5	11	11
Interest cost	149	181	299	362
Amortization of prior service cost	0	13	0	25
Amortization of net loss	96	69	192	138
Net periodic benefit cost	$ (251)	$ (268)	$ (502)	$ (536)

XML

Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting [Abstract]
Income from operations	$ 295,374	$ 266,788	$ 524,654	$ 514,843
Interest expense	(8,958)	(9,539)	(18,549)	(18,696)
Other income, net	22,058	4,601	31,154	7,110
Income before income taxes	$ 308,474	$ 261,850	$ 537,259	$ 503,257

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Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net income	$ 210,061	$ 169,443	$ 360,468	$ 327,475
Depreciation and amortization			119,983	95,204
Deferred income taxes			3,088	19,359
Net changes in working capital and other			(48,184)	(9,796)
Net cash provided by operating activities			435,355	432,242
Acquisition of business, net of cash acquired			(15,782)	0
Additions to property, plant and equipment	(108,110)	(106,171)	(203,933)	(216,912)
Proceeds from disposition of assets			0	13
Proceeds from sales and maturities of securities			15,037	342,045
Purchase of securities			0	(117,332)
Settlements of derivative instruments			(1,174)	(290)
Net cash used for investing activities			(174,288)	7,524
Intercompany financing			0	0
Intercompany financing—OpCo			0
Net distributions prior to Westlake Partners initial public offering				0
Dividends paid			(43,896)	(33,623)
Distributions paid			(7,218)
Proceeds from exercise of stock options			831	4,187
Proceeds from issuance of notes payable			2,392	0
Repayment of notes payable			(4,299)	0
Repurchase of common stock for treasury			(62,804)
Windfall tax benefits from share-based payment arrangements			1,895	4,436
Net cash provided by financing activities			(113,099)	(25,000)
Effect of exchange rate changes on cash and cash equivalents			(2,000)	0
Net increase in cash and cash equivalents			145,968	414,766
Cash and cash equivalents at beginning of period			880,601	461,301
Cash and cash equivalents at end of period	1,026,569	876,067	1,026,569	876,067
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net income	205,095		351,437	327,475
Depreciation and amortization			1,002	730
Deferred income taxes			(40)	(292)
Net changes in working capital and other			(371,716)	(336,669)
Net cash provided by operating activities			(19,317)	(8,756)
Acquisition of business, net of cash acquired			0
Additions to property, plant and equipment			0	0
Proceeds from disposition of assets				0
Proceeds from sales and maturities of securities			15,037	342,045
Purchase of securities				(117,332)
Settlements of derivative instruments			0	0
Net cash used for investing activities			15,037	224,713
Intercompany financing			208,692	221,745
Intercompany financing—OpCo			0
Net distributions prior to Westlake Partners initial public offering				0
Dividends paid			(43,896)	(33,623)
Distributions paid			0
Proceeds from exercise of stock options			831	4,187
Proceeds from issuance of notes payable			0
Repayment of notes payable			0
Repurchase of common stock for treasury			(62,804)
Windfall tax benefits from share-based payment arrangements			1,895	4,436
Net cash provided by financing activities			104,718	196,745
Effect of exchange rate changes on cash and cash equivalents			0
Net increase in cash and cash equivalents			100,438	412,702
Cash and cash equivalents at beginning of period			655,947	420,948
Cash and cash equivalents at end of period	756,385	833,650	756,385	833,650
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	167,066		304,242	334,394
Depreciation and amortization			59,792	54,121
Deferred income taxes			929	12,931
Net changes in working capital and other			(310,600)	(336,097)
Net cash provided by operating activities			54,363	65,349
Acquisition of business, net of cash acquired			0
Additions to property, plant and equipment			(95,363)	(110,338)
Proceeds from disposition of assets				12
Proceeds from sales and maturities of securities			0	0
Purchase of securities				0
Settlements of derivative instruments			(1,174)	0
Net cash used for investing activities			(96,537)	(110,326)
Intercompany financing			(269,281)	(329,044)
Intercompany financing—OpCo			135,341
Net distributions prior to Westlake Partners initial public offering				376,613
Dividends paid			0	0
Distributions paid			176,980
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
Windfall tax benefits from share-based payment arrangements			0	0
Net cash provided by financing activities			43,040	47,569
Effect of exchange rate changes on cash and cash equivalents			0
Net increase in cash and cash equivalents			866	2,592
Cash and cash equivalents at beginning of period			3,057	6,227
Cash and cash equivalents at end of period	3,923	8,819	3,923	8,819
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Net income	88,556		177,899	297,718
Depreciation and amortization			40,195	39,282
Deferred income taxes			(234)	6,813
Net changes in working capital and other			15,748	35,108
Net cash provided by operating activities			233,608	378,921
Acquisition of business, net of cash acquired			0
Additions to property, plant and equipment			(95,514)	(106,191)
Proceeds from disposition of assets				0
Proceeds from sales and maturities of securities			0	0
Purchase of securities				0
Settlements of derivative instruments			0	(290)
Net cash used for investing activities			(95,514)	(106,481)
Intercompany financing			53,354	104,173
Intercompany financing—OpCo			(135,341)
Net distributions prior to Westlake Partners initial public offering				(376,613)
Dividends paid			0	0
Distributions paid			(189,103)
Purchase of limited partner interests			135,341
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
Windfall tax benefits from share-based payment arrangements			0	0
Net cash provided by financing activities			(135,749)	(272,440)
Effect of exchange rate changes on cash and cash equivalents			0
Net increase in cash and cash equivalents			2,345	0
Cash and cash equivalents at beginning of period			131,545	0
Cash and cash equivalents at end of period	133,890	0	133,890	0
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	43,788		59,996	(2,102)
Depreciation and amortization			18,994	1,071
Deferred income taxes			2,433	(93)
Net changes in working capital and other			85,278	(2,148)
Net cash provided by operating activities			166,701	(3,272)
Acquisition of business, net of cash acquired			(15,782)
Additions to property, plant and equipment			(13,056)	(383)
Proceeds from disposition of assets				1
Proceeds from sales and maturities of securities			0	0
Purchase of securities				0
Settlements of derivative instruments			0	0
Net cash used for investing activities			2,726	(382)
Intercompany financing			7,235	3,126
Intercompany financing—OpCo			0
Net distributions prior to Westlake Partners initial public offering				0
Dividends paid			0	0
Distributions paid			4,905
Purchase of limited partner interests			(135,341)
Proceeds from exercise of stock options			0	0
Proceeds from issuance of notes payable			2,392
Repayment of notes payable			(4,299)
Repurchase of common stock for treasury			0
Windfall tax benefits from share-based payment arrangements			0	0
Net cash provided by financing activities			(125,108)	3,126
Effect of exchange rate changes on cash and cash equivalents			(2,000)
Net increase in cash and cash equivalents			42,319	(528)
Cash and cash equivalents at beginning of period			90,052	34,126
Cash and cash equivalents at end of period	132,371	33,598	132,371	33,598
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income	(294,444)		(533,106)	(630,010)
Depreciation and amortization			0	0
Deferred income taxes			0	0
Net changes in working capital and other			533,106	630,010
Net cash provided by operating activities			0	0
Acquisition of business, net of cash acquired			0
Additions to property, plant and equipment			0	0
Proceeds from disposition of assets				0
Proceeds from sales and maturities of securities			0	0
Purchase of securities				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
Dividends paid			0	0
Distributions paid			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
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
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

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Segment Information (Total Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 5,411,010	$ 5,213,990
Olefins
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,844,391	1,785,895
Vinyls
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,656,936	2,618,646
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 909,683	$ 809,449

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Acquisition (Assets Acquired and Liabilities Assumed - Huasu) (Details) - Jun. 01, 2015 - Suzhou Huasu Plastics Company Ltd [Member] - USD ($) $ in Thousands	Total
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

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Commitments and Contingencies

6 Months Ended

Jun. 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.

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Other Assets (Additional Information) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Other Assets [Line Items]
Amortization expense on intangible assets, included in other assets	$ 9,578	$ 9,008	$ 19,062	$ 17,284
Olefins
Other Assets [Line Items]
Goodwill	29,990		29,990		$ 29,990
Vinyls
Other Assets [Line Items]
Goodwill	$ 32,026		$ 32,026		$ 32,026

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Segment Information (Tables)

6 Months Ended

Jun. 30, 2015

Segment Reporting [Abstract]

Segment Reporting Information

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Net external sales
Olefins
Polyethylene	$	450,482		$	475,503		$	859,914		$	962,647
Styrene, feedstock and other	170,396			223,550			344,041			459,204
Total Olefins	620,878			699,053			1,203,955			1,421,851
Vinyls
PVC, caustic soda and other	429,878			168,762			846,866			359,289
Building products	134,246			130,761			237,712			245,112
Total Vinyls	564,124			299,523			1,084,578			604,401
	$	1,185,002		$	998,576		$	2,288,533		$	2,026,252
Intersegment sales
Olefins	$	26,641		$	34,782		$	50,103		$	91,635
Vinyls	387			331			757			674
	$	27,028		$	35,113		$	50,860		$	92,309
Income (loss) from operations
Olefins	$	220,938		$	238,657		$	412,041		$	510,990
Vinyls	87,966			38,129			135,052			17,015
Corporate and other	(13,530		)	(9,998		)	(22,439		)	(13,162		)
	$	295,374		$	266,788		$	524,654		$	514,843
Depreciation and amortization
Olefins	$	27,623		$	26,721		$	54,562		$	53,368
Vinyls	32,599			21,623			64,183			40,791
Corporate and other	118			158			236			315
	$	60,340		$	48,502		$	118,981		$	94,474
Other income (expense), net
Olefins	$	(104	)	$	1,199		$	2,448		$	2,653
Vinyls	1,413			(213		)	6,916			(247		)
Corporate and other	20,749			3,615			21,790			4,704
	$	22,058		$	4,601		$	31,154		$	7,110
Provision for (benefit from) income taxes
Olefins	$	74,212		$	83,502		$	140,669		$	177,052
Vinyls	26,653			10,430			39,458			360
Corporate and other	(2,452		)	(1,525		)	(3,336		)	(1,630		)
	$	98,413		$	92,407		$	176,791		$	175,782
Capital expenditures
Olefins	$	81,534		$	43,448		$	136,835		$	72,522
Vinyls	24,569			62,262			61,425			143,382
Corporate and other	2,007			461			5,673			1,008
	$	108,110		$	106,171		$	203,933		$	216,912

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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Income from operations	$	295,374		$	266,788		$	524,654		$	514,843
Interest expense	(8,958		)	(9,539		)	(18,549		)	(18,696		)
Other income, net	22,058			4,601			31,154			7,110
Income before income taxes	$	308,474		$	261,850		$	537,259		$	503,257

Total Assets

	June 30, 2015		December 31, 2014
Total assets
Olefins	$	1,844,391	$	1,785,895
Vinyls	2,656,936		2,618,646
Corporate and other	909,683		809,449
	$	5,411,010	$	5,213,990

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Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net external sales	$ 1,185,002	$ 998,576	$ 2,288,533	$ 2,026,252
Income (loss) from operations	295,374	266,788	524,654	514,843
Depreciation and amortization	60,340	48,502	118,981	94,474
Other income (expense), net	22,058	4,601	31,154	7,110
Provision for (benefit from) income taxes	98,413	92,407	176,791	175,782
Capital expenditures	108,110	106,171	203,933	216,912
Olefins
Segment Reporting Information [Line Items]
Net external sales	620,878	699,053	1,203,955	1,421,851
Income (loss) from operations	220,938	238,657	412,041	510,990
Depreciation and amortization	27,623	26,721	54,562	53,368
Other income (expense), net	(104)	1,199	2,448	2,653
Provision for (benefit from) income taxes	74,212	83,502	140,669	177,052
Capital expenditures	81,534	43,448	136,835	72,522
Vinyls
Segment Reporting Information [Line Items]
Net external sales	564,124	299,523	1,084,578	604,401
Income (loss) from operations	87,966	38,129	135,052	17,015
Depreciation and amortization	32,599	21,623	64,183	40,791
Other income (expense), net	1,413	(213)	6,916	(247)
Provision for (benefit from) income taxes	26,653	10,430	39,458	360
Capital expenditures	24,569	62,262	61,425	143,382
Corporate and Other
Segment Reporting Information [Line Items]
Income (loss) from operations	(13,530)	(9,998)	(22,439)	(13,162)
Depreciation and amortization	118	158	236	315
Other income (expense), net	20,749	3,615	21,790	4,704
Provision for (benefit from) income taxes	(2,452)	(1,525)	(3,336)	(1,630)
Capital expenditures	2,007	461	5,673	1,008
Polyethylene | Olefins
Segment Reporting Information [Line Items]
Net external sales	450,482	475,503	859,914	962,647
Ethylene, Styrene And Other | Olefins
Segment Reporting Information [Line Items]
Net external sales	170,396	223,550	344,041	459,204
PVC, Caustic Soda And Other | Vinyls
Segment Reporting Information [Line Items]
Net external sales	429,878	168,762	846,866	359,289
Building Products | Vinyls
Segment Reporting Information [Line Items]
Net external sales	134,246	130,761	237,712	245,112
Intersegment sales
Segment Reporting Information [Line Items]
Net external sales	27,028	35,113	50,860	92,309
Intersegment sales | Olefins
Segment Reporting Information [Line Items]
Net external sales	26,641	34,782	50,103	91,635
Intersegment sales | Vinyls
Segment Reporting Information [Line Items]
Net external sales	$ 387	$ 331	$ 757	$ 674

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Derivative Instruments (Tables)

6 Months Ended

Jun. 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
		June 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	2,439	$	3,145
Commodity forward contracts	Deferred charges and    other assets, net	2,433		—
Total derivative assets		$	4,872	$	3,145

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		June 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	3,446	$	6,549
Commodity forward contracts	Other liabilities	3,047		3,559
Total derivative liabilities		$	6,493	$	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 June 30,				Six Months Ended June 30,
		2015		2014		2015		2014
Commodity forward contracts	Gross profit	$	595	$	240	$	4,836	$	(371	)

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Long-Term Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt	$ 764,056	$ 763,997
3.60% Senior Notes Due 2022
Debt Instrument [Line Items]
Maturity	2022
Stated interest rate	3.60%
Senior notes	$ 249,167	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

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Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 205,095	$ 169,443	$ 351,437	$ 327,475
Less: Net income attributable to participating securities	(253)	(360)	(457)	(746)
Net income attributable to common shareholders	$ 204,842	$ 169,083	$ 350,980	$ 326,729

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Derivative Instruments (Fair Values of Derivative Instruments in Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accrued liabilities
Derivatives, Fair Value [Line Items]
Total derivative liabilities	$ 6,493	$ 10,108
Accounts receivable, net
Derivatives, Fair Value [Line Items]
Total derivative assets	4,872	3,145
Forward Contracts [Member] | Accrued liabilities
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Liabilities	3,446	6,549
Forward Contracts [Member] | Accounts receivable, net
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Assets	2,439	3,145
Forward Contracts [Member] | Deferred charges and other assets, net
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Assets	2,433	0
Commodity Forward Contracts [Member] | Other liabilities
Derivatives, Fair Value [Line Items]
Not designated as hedging instruments, Derivative Liabilities	$ 3,047	$ 3,559

XML

Accounts Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accounts Receivable, Net [Abstract]
Trade customers	$ 575,609	$ 525,546
Affiliates	0	437
Allowance for doubtful accounts	(13,468)	(13,468)
Receivables from trade customers and affiliates, net	562,141	512,515
Federal and state taxes	11,746	8,919
Other	26,835	39,232
Accounts receivable, net	$ 600,722	$ 560,666

XML

Accounts Receivable

6 Months Ended

Jun. 30, 2015

Accounts Receivable, Net [Abstract]

Accounts Receivable

Accounts Receivable

Accounts receivable consist of the following:

	June 30, 2015			December 31, 2014
Trade customers	$	575,609		$	525,546
Affiliates	—			437
Allowance for doubtful accounts	(13,468		)	(13,468		)
	562,141			512,515
Federal and state taxes	11,746			8,919
Other	26,835			39,232
Accounts receivable, net	$	600,722		$	560,666

XML

Derivative Instruments (Impact of Derivative Instruments on Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 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	$ 595	$ 240	$ 4,836	$ (371)

XML

Guarantor Disclosures (Tables)

6 Months Ended

Jun. 30, 2015

Guarantees [Abstract]

Condensed Consolidating Financial Information Balance Sheet

Condensed Consolidating Financial Information as of June 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	$	756,385	$	3,923	$	133,890	$	132,371	$	—		$	1,026,569
Accounts receivable, net	13,335		1,995,787		57,957		144,560		(1,610,917		)	600,722
Inventories	—		376,750		3,856		105,691		—			486,297
Prepaid expenses and other current assets	136		20,981		30		4,132		(2,261		)	23,018
Deferred income taxes	409		29,832		—		279		(886		)	29,634
Total current assets	770,265		2,427,273		195,733		387,033		(1,614,064		)	2,166,240
Property, plant and equipment, net	—		1,520,734		914,270		420,504		—			2,855,508
Equity investments	4,690,426		1,228,964		—		467,530		(6,349,174		)	37,746
Other assets, net	18,920		300,172		50,018		133,840		(151,434		)	351,516
Total assets	$	5,479,611	$	5,477,143	$	1,160,021	$	1,408,907	$	(8,114,672	)	$	5,411,010
Current liabilities
Accounts and notes payable	$	1,594,555	$	145,719	$	36,339	$	104,954	$	(1,598,589	)	$	282,978
Accrued liabilities	8,501		173,112		16,441		69,101		(15,475		)	251,680
Total current liabilities	1,603,056		318,831		52,780		174,055		(1,614,064		)	534,658
Long-term debt	753,167		10,889		145,651		—		(145,651		)	764,056
Deferred income taxes	—		498,993		1,614		37,520		(5,783		)	532,344
Other liabilities	—		39,553		—		123,224		—			162,777
Total liabilities	2,356,223		868,266		200,045		334,799		(1,765,498		)	1,993,835
Total Westlake Chemical Corporation stockholders' equity	3,123,388		4,608,877		959,976		780,321		(6,349,174		)	3,123,388
Noncontrolling interests	—		—		—		293,787		—			293,787
Total equity	3,123,388		4,608,877		959,976		1,074,108		(6,349,174		)	3,417,175
Total liabilities and equity	$	5,479,611	$	5,477,143	$	1,160,021	$	1,408,907	$	(8,114,672	)	$	5,411,010

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 June 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	$	—		$	990,434		$	251,705		$	250,365		$	(307,502	)	$	1,185,002
Cost of sales	—			750,892			157,177			226,283			(302,531		)	831,821
Gross profit	—			239,542			94,528			24,082			(4,971		)	353,181
Selling, general and administrative expenses	399			42,682			5,191			14,506			(4,971		)	57,807
(Loss) income from operations	(399		)	196,860			89,337			9,576			—			295,374
Interest expense	(10,569		)	(4		)	(856		)	(52		)	2,523			(8,958		)
Other income (expense), net	9,776			(9,371		)	34			24,142			(2,523		)	22,058
(Loss) income before income taxes	(1,192		)	187,485			88,515			33,666			—			308,474
(Benefit from) provision for income taxes	(399		)	97,218			(41		)	1,635			—			98,413
Equity in net income of subsidiaries	205,888			76,799			—			11,757			(294,444		)	—
Net income	205,095			167,066			88,556			43,788			(294,444		)	210,061
Net income attributable to noncontrolling interests	—			—			—			4,966			—			4,966
Net income attributable to Westlake Chemical Corporation	$	205,095		$	167,066		$	88,556		$	38,822		$	(294,444	)	$	205,095
Comprehensive income attributable to    Westlake Chemical Corporation	$	222,833		$	167,206		$	88,556		$	56,879		$	(312,641	)	$	222,833

Condensed Consolidating Financial Information for the Three Months Ended June 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	$	—		$	879,842		$	524,135		$	11,753		$	(417,154	)	$	998,576
Cost of sales	—			821,234			277,589			10,936			(417,154		)	692,605
Gross profit	—			58,608			246,546			817			—			305,971
Selling, general and administrative expenses	529			31,066			6,165			1,423			—			39,183
(Loss) income from operations	(529		)	27,542			240,381			(606		)	—			266,788
Interest expense	(9,535		)	(4		)	(4,105		)	—			4,105			(9,539		)
Other income (expense), net	7,137			965			1,397			(793		)	(4,105		)	4,601
(Loss) income before income taxes	(2,927		)	28,503			237,673			(1,399		)	—			261,850
(Benefit from) provision for income taxes	(1,039		)	9,766			83,829			(149		)	—			92,407
Equity in net income of subsidiaries	171,331			153,844			—			—			(325,175		)	—
Net income (loss) attributable to Westlake Chemical Corporation	$	169,443		$	172,581		$	153,844		$	(1,250	)	$	(325,175	)	$	169,443
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	171,093		$	172,701		$	153,844		$	(442	)	$	(326,103	)	$	171,093

Condensed Consolidating Financial Information Statement Of Cash Flows

Condensed Consolidating Financial Information as of June 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	$	756,385	$	3,923	$	133,890	$	132,371	$	—		$	1,026,569
Accounts receivable, net	13,335		1,995,787		57,957		144,560		(1,610,917		)	600,722
Inventories	—		376,750		3,856		105,691		—			486,297
Prepaid expenses and other current assets	136		20,981		30		4,132		(2,261		)	23,018
Deferred income taxes	409		29,832		—		279		(886		)	29,634
Total current assets	770,265		2,427,273		195,733		387,033		(1,614,064		)	2,166,240
Property, plant and equipment, net	—		1,520,734		914,270		420,504		—			2,855,508
Equity investments	4,690,426		1,228,964		—		467,530		(6,349,174		)	37,746
Other assets, net	18,920		300,172		50,018		133,840		(151,434		)	351,516
Total assets	$	5,479,611	$	5,477,143	$	1,160,021	$	1,408,907	$	(8,114,672	)	$	5,411,010
Current liabilities
Accounts and notes payable	$	1,594,555	$	145,719	$	36,339	$	104,954	$	(1,598,589	)	$	282,978
Accrued liabilities	8,501		173,112		16,441		69,101		(15,475		)	251,680
Total current liabilities	1,603,056		318,831		52,780		174,055		(1,614,064		)	534,658
Long-term debt	753,167		10,889		145,651		—		(145,651		)	764,056
Deferred income taxes	—		498,993		1,614		37,520		(5,783		)	532,344
Other liabilities	—		39,553		—		123,224		—			162,777
Total liabilities	2,356,223		868,266		200,045		334,799		(1,765,498		)	1,993,835
Total Westlake Chemical Corporation stockholders' equity	3,123,388		4,608,877		959,976		780,321		(6,349,174		)	3,123,388
Noncontrolling interests	—		—		—		293,787		—			293,787
Total equity	3,123,388		4,608,877		959,976		1,074,108		(6,349,174		)	3,417,175
Total liabilities and equity	$	5,479,611	$	5,477,143	$	1,160,021	$	1,408,907	$	(8,114,672	)	$	5,411,010

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 June 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	$	—		$	990,434		$	251,705		$	250,365		$	(307,502	)	$	1,185,002
Cost of sales	—			750,892			157,177			226,283			(302,531		)	831,821
Gross profit	—			239,542			94,528			24,082			(4,971		)	353,181
Selling, general and administrative expenses	399			42,682			5,191			14,506			(4,971		)	57,807
(Loss) income from operations	(399		)	196,860			89,337			9,576			—			295,374
Interest expense	(10,569		)	(4		)	(856		)	(52		)	2,523			(8,958		)
Other income (expense), net	9,776			(9,371		)	34			24,142			(2,523		)	22,058
(Loss) income before income taxes	(1,192		)	187,485			88,515			33,666			—			308,474
(Benefit from) provision for income taxes	(399		)	97,218			(41		)	1,635			—			98,413
Equity in net income of subsidiaries	205,888			76,799			—			11,757			(294,444		)	—
Net income	205,095			167,066			88,556			43,788			(294,444		)	210,061
Net income attributable to noncontrolling interests	—			—			—			4,966			—			4,966
Net income attributable to Westlake Chemical Corporation	$	205,095		$	167,066		$	88,556		$	38,822		$	(294,444	)	$	205,095
Comprehensive income attributable to    Westlake Chemical Corporation	$	222,833		$	167,206		$	88,556		$	56,879		$	(312,641	)	$	222,833

Condensed Consolidating Financial Information for the Three Months Ended June 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	$	—		$	879,842		$	524,135		$	11,753		$	(417,154	)	$	998,576
Cost of sales	—			821,234			277,589			10,936			(417,154		)	692,605
Gross profit	—			58,608			246,546			817			—			305,971
Selling, general and administrative expenses	529			31,066			6,165			1,423			—			39,183
(Loss) income from operations	(529		)	27,542			240,381			(606		)	—			266,788
Interest expense	(9,535		)	(4		)	(4,105		)	—			4,105			(9,539		)
Other income (expense), net	7,137			965			1,397			(793		)	(4,105		)	4,601
(Loss) income before income taxes	(2,927		)	28,503			237,673			(1,399		)	—			261,850
(Benefit from) provision for income taxes	(1,039		)	9,766			83,829			(149		)	—			92,407
Equity in net income of subsidiaries	171,331			153,844			—			—			(325,175		)	—
Net income (loss) attributable to Westlake Chemical Corporation	$	169,443		$	172,581		$	153,844		$	(1,250	)	$	(325,175	)	$	169,443
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	171,093		$	172,701		$	153,844		$	(442	)	$	(326,103	)	$	171,093

Condensed Consolidating Financial Information for the Six Months Ended June 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	$	—		$	1,901,365		$	510,096		$	496,007		$	(618,935	)	$	2,288,533
Cost of sales	—			1,485,728			319,341			454,553			(608,816		)	1,650,806
Gross profit	—			415,637			190,755			41,454			(10,119		)	637,727
Selling, general and administrative expenses	812			86,366			10,237			25,777			(10,119		)	113,073
(Loss) income from operations	(812		)	329,271			180,518			15,677			—			524,654
Interest expense	(21,321		)	(5		)	(2,232		)	(94		)	5,103			(18,549		)
Other income (expense), net	16,387			(6,544		)	39			26,375			(5,103		)	31,154
(Loss) income before income taxes	(5,746		)	322,722			178,325			41,958			—			537,259
(Benefit from) provision for income taxes	(1,976		)	175,170			426			3,171			—			176,791
Equity in net income of subsidiaries	355,207			156,690			—			21,209			(533,106		)	—
Net income	351,437			304,242			177,899			59,996			(533,106		)	360,468
Net income attributable to noncontrolling interests	—			—			—			9,031			—			9,031
Net income attributable to Westlake Chemical Corporation	$	351,437		$	304,242		$	177,899		$	50,965		$	(533,106	)	$	351,437
Comprehensive income attributable to    Westlake Chemical Corporation	$	310,946		$	304,620		$	177,899		$	9,513		$	(492,032	)	$	310,946

Condensed Consolidating Financial Information for the Six Months Ended June 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	$	—		$	1,724,184		$	1,084,149		$	20,870		$	(802,951	)	$	2,026,252
Cost of sales	—			1,611,811			605,289			19,122			(802,951		)	1,433,271
Gross profit	—			112,373			478,860			1,748			—			592,981
Selling, general and administrative expenses	1,075			60,351			13,943			2,769			—			78,138
(Loss) income from operations	(1,075		)	52,022			464,917			(1,021		)	—			514,843
Interest expense	(18,690		)	(6		)	(7,696		)	—			7,696			(18,696		)
Other income (expense), net	12,351			1,213			2,649			(1,407		)	(7,696		)	7,110
(Loss) income before income taxes	(7,414		)	53,229			459,870			(2,428		)	—			503,257
(Benefit from) provision for income taxes	(2,597		)	16,553			162,152			(326		)	—			175,782
Equity in net income of subsidiaries	332,292			297,718			—			—			(630,010		)	—
Net income (loss) attributable to Westlake Chemical Corporation	$	327,475		$	334,394		$	297,718		$	(2,102	)	$	(630,010	)	$	327,475
Comprehensive income (loss) attributable to    Westlake Chemical Corporation	$	329,959		$	334,649		$	297,718		$	(2,192	)	$	(630,175	)	$	329,959

Condensed Consolidating Financial Information for the Six Months Ended June 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	$	351,437		$	304,242		$	177,899		$	59,996		$	(533,106	)	$	360,468
Adjustments to reconcile net income to net cash (used for)    provided by operating activities
Depreciation and amortization	1,002			59,792			40,195			18,994			—			119,983
Deferred income taxes	(40		)	929			(234		)	2,433			—			3,088
Net changes in working capital and other	(371,716		)	(310,600		)	15,748			85,278			533,106			(48,184		)
Net cash (used for) provided by operating activities	(19,317		)	54,363			233,608			166,701			—			435,355
Cash flows from investing activities
Acquisition of business, net of cash acquired	—			—			—			15,782			—			15,782
Additions to property, plant and equipment	—			(95,363		)	(95,514		)	(13,056		)	—			(203,933		)
Proceeds from sales and maturities of securities	15,037			—			—			—			—			15,037
Settlements of derivative instruments	—			(1,174		)	—			—			—			(1,174		)
Net cash provided by (used for) investing activities	15,037			(96,537		)	(95,514		)	2,726			—			(174,288		)
Cash flows from financing activities
Intercompany financing	208,692			(269,281		)	53,354			7,235			—			—
Intercompany financing—OpCo	—			135,341			(135,341		)	—			—			—
Dividends paid	(43,896		)	—			—			—			—			(43,896		)
Distributions paid	—			176,980			(189,103		)	4,905			—			(7,218		)
Purchase of limited partner interests	—			—			135,341			(135,341		)	—			—
Proceeds from exercise of stock options	831			—			—			—			—			831
Proceeds from issuance of notes payable	—			—			—			2,392			—			2,392
Repayment of notes payable	—			—			—			(4,299		)	—			(4,299		)
Repurchase of common stock for treasury	(62,804		)	—			—			—			—			(62,804		)
Windfall tax benefits from share-based payment arrangements	1,895			—			—			—			—			1,895
Net cash provided by (used for) financing activities	$	104,718		$	43,040		$	(135,749	)	$	(125,108	)	$	—		$	(113,099	)

	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	$	—	$	—	$	—	$	(2,000	)	$	—	$	(2,000	)
Net increase in cash and cash equivalents	100,438		866		2,345		42,319			—		145,968
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	$	756,385	$	3,923	$	133,890	$	132,371		$	—	$	1,026,569

Condensed Consolidating Financial Information for the Six Months Ended June 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)	$	327,475		$	334,394		$	297,718		$	(2,102	)	$	(630,010	)	$	327,475
Adjustments to reconcile net income (loss) to net cash (used for)    provided by operating activities
Depreciation and amortization	730			54,121			39,282			1,071			—			95,204
Deferred income taxes	(292		)	12,931			6,813			(93		)	—			19,359
Net changes in working capital and other	(336,669		)	(336,097		)	35,108			(2,148		)	630,010			(9,796		)
Net cash (used for) provided by operating activities	(8,756		)	65,349			378,921			(3,272		)	—			432,242
Cash flows from investing activities
Additions to property, plant and equipment	—			(110,338		)	(106,191		)	(383		)	—			(216,912		)
Proceeds from disposition of assets	—			12			—			1			—			13
Proceeds from sales and maturities of securities	342,045			—			—			—			—			342,045
Purchase of securities	(117,332		)	—			—			—			—			(117,332		)
Settlements of derivative instruments	—			—			(290		)	—			—			(290		)
Net cash provided by (used for) investing activities	224,713			(110,326		)	(106,481		)	(382		)	—			7,524
Cash flows from financing activities
Intercompany financing	221,745			(329,044		)	104,173			3,126			—			—
Net distributions prior to Westlake Partners initial public offering	—			376,613			(376,613		)	—			—			—
Dividends paid	(33,623		)	—			—			—			—			(33,623		)
Proceeds from exercise of stock options	4,187			—			—			—			—			4,187
Windfall tax benefits from share-based payment arrangements	4,436			—			—			—			—			4,436
Net cash provided by (used for) financing activities	196,745			47,569			(272,440		)	3,126			—			(25,000		)
Net increase (decrease) in cash and cash equivalents	412,702			2,592			—			(528		)	—			414,766
Cash and cash equivalents at beginning of period	420,948			6,227			—			34,126			—			461,301
Cash and cash equivalents at end of period	$	833,650		$	8,819		$	—		$	33,598		$	—		$	876,067

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Basis of Financial Statements (Policies)

6 Months Ended

Jun. 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 June 30, 2015, its results of operations for the three and six months ended June 30, 2015 and 2014 and the changes in its cash position for the six months ended June 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 interim periods within those fiscal years, and is not expected to have an impact on the Company's consolidated financial position, results of operations and cash flows.

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Guarantor Disclosures

6 Months Ended

Jun. 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.

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Stockholders' Equity (Reclassifications in AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of benefits liability	$ 675		$ 226		$ 1,327		$ 445
Realized gain on available-for-sale investments	22,058		4,601		31,154		7,110
Provision for income taxes	(98,413)		(92,407)		(176,791)		(175,782)
Net income attributable to Westlake Chemical Corporation	205,095		169,443		351,437		327,475
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income attributable to Westlake Chemical Corporation	1,992		653		1,565		502
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]	(173)
Amortization of benefits liability	(675)	[1]	(139)	[1]	(1,327)	[1]	(272)
(Loss) income before income taxes	(675)		(226)		(1,327)		(445)
Provision for income taxes	235		86		460		170
Net income attributable to Westlake Chemical Corporation	(440)		(140)		(867)		(275)
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	3,795		1,237		3,795		1,212
Provision for income taxes	(1,363)		(444)		(1,363)		(435)
Net income attributable to Westlake Chemical Corporation	$ 2,432		$ 793		$ 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.

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Financial Instruments Cash Equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Held-to-maturity Securities
Cash Equivalents [Line Items]
Cash equivalents	$ 654,739	$ 509,811

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Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2015

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

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

	June 30, 2015		December 31, 2014
Non-current	$	5,074	$	15,414
Total available-for-sale securities	$	5,074	$	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:

	June 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	3,802	$	1,272	$	—	$	5,074
Total available-for-sale securities	$	3,802	$	1,272	$	—	$	5,074

	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 June 30,					Six Months Ended June 30,
	2015		2014			2015		2014
Proceeds from sales and maturities of securities	$	15,037	$	311,926		$	15,037	$	342,045
Gross realized gains	3,795		1,298			3,795		1,311
Gross realized losses	—		(61		)	—		(99		)

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Accounts Receivable (Tables)

6 Months Ended

Jun. 30, 2015

Accounts Receivable, Net [Abstract]

Schedule Of Accounts Receivable

Accounts receivable consist of the following:

	June 30, 2015			December 31, 2014
Trade customers	$	575,609		$	525,546
Affiliates	—			437
Allowance for doubtful accounts	(13,468		)	(13,468		)
	562,141			512,515
Federal and state taxes	11,746			8,919
Other	26,835			39,232
Accounts receivable, net	$	600,722		$	560,666

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Financial Instruments

6 Months Ended

Jun. 30, 2015

Investments, Debt and Equity Securities [Abstract]

Financial Instruments

Financial Instruments

Cash Equivalents

The Company had $654,739 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 June 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:

	June 30, 2015		December 31, 2014
Non-current	$	5,074	$	15,414
Total available-for-sale securities	$	5,074	$	15,414

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

	June 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	3,802	$	1,272	$	—	$	5,074
Total available-for-sale securities	$	3,802	$	1,272	$	—	$	5,074

	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 June 30, 2015 and December 31, 2014, net unrealized gains on the Company's available-for-sale securities of $816 and $233, respectively, net of income tax expense of $456 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.

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 June 30,					Six Months Ended June 30,
	2015		2014			2015		2014
Proceeds from sales and maturities of securities	$	15,037	$	311,926		$	15,037	$	342,045
Gross realized gains	3,795		1,298			3,795		1,311
Gross realized losses	—		(61		)	—		(99		)

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Inventories (Tables)

6 Months Ended

Jun. 30, 2015

Inventory Disclosure [Abstract]

Schedule Of Inventory

Inventories consist of the following:

	June 30, 2015		December 31, 2014
Finished products	$	280,317	$	300,909
Feedstock, additives and chemicals	134,369		158,635
Materials and supplies	71,611		66,232
Inventories	$	486,297	$	525,776

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Supplemental Information Other Income, Net (Tables)

6 Months Ended

Jun. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Other Income, Net

Other Income, Net

	Three Months Ended June 30,					Six Months Ended June 30,
	2015			2014		2015			2014
Interest income	$	866		$	1,105	$	1,751		$	2,328
Dividend income	1,357			—		3,329			—
Foreign exchange currency (losses) gains, net	(500		)	3		1,871			(245		)
(Loss) income from equity method investments	(350		)	1,920		4,613			3,941
Impairment of equity method investment	(4,925		)	—		(4,925		)	—
Gain on acquisition and related expenses, net	20,430			—		20,430			—
Gain from sales of equity securities	3,795			—		3,795			—
Other	1,385			1,573		290			1,086
Other income, net	$	22,058		$	4,601	$	31,154		$	7,110

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Long-Term Debt (Revolving Credit Facility) (Details) - Jun. 30, 2015 - Line of Credit - USD ($)	Total
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	$ 29,670,000
Remaining borrowing capacity	$ 370,330,000
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%

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Insurance Recovery (Details) $ in Thousands	3 Months Ended
	Jun. 30, 2015 USD ($)
Insurance Recovery [Abstract]
Insurance Recovery	$ 4,470

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Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 1,026,569	$ 880,601
Accounts receivable, net	600,722	560,666
Inventories	486,297	525,776
Prepaid expenses and other current assets	23,018	11,807
Deferred income taxes	29,634	32,437
Total current assets	2,166,240	2,011,287
Property, plant and equipment, net	2,855,508	2,757,557
Equity investments	37,746	61,305
Other assets, net
Intangible assets, net	213,968	218,431
Deferred charges and other assets, net	137,548	165,410
Total other assets, net	351,516	383,841
Total assets	5,411,010	5,213,990
Current liabilities
Accounts and notes payable	282,978	261,062
Accrued liabilities	251,680	276,118
Total current liabilities	534,658	537,180
Long-term debt	764,056	763,997
Deferred income taxes	532,344	536,066
Other liabilities	162,777	174,859
Total liabilities	$ 1,993,835	$ 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; 134,679,064 shares issued at June 30, 2015 and December 31, 2014	1,347	1,347
Common stock, held in treasury, at cost; 2,646,260 and 1,787,546 shares at June 30, 2015 and December 31, 2014, respectively	(158,472)	(96,372)
Additional paid-in capital	537,368	530,441
Retained earnings	2,863,069	2,555,528
Accumulated other comprehensive loss	(119,924)	(79,433)
Total Westlake Chemical Corporation stockholders' equity	3,123,388	2,911,511
Noncontrolling interests	293,787	290,377
Total equity	3,417,175	3,201,888
Total liabilities and equity	$ 5,411,010	$ 5,213,990

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Financial Instruments (Marketable Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Noncurrent	$ 5,074	$ 15,414
Total available-for-sale securities	$ 5,074	$ 15,414

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Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities
Net income	$ 360,468	$ 327,475
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	118,981	94,474
Recovery of doubtful accounts	228	311
Amortization of debt issuance costs	1,002	730
Stock-based compensation expense	4,905	4,511
Loss from disposition of fixed assets	890	1,872
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	3,088	19,359
Windfall tax benefits from share-based payment arrangements	(1,895)	(4,436)
Income from equity method investments, net of dividends	(1,760)	(1,239)
Other gains (losses), net	423	(526)
Changes in operating assets and liabilities
Accounts receivable	(22,380)	(27,367)
Inventories	50,115	34,360
Prepaid expenses and other current assets	(10,844)	(5,480)
Accounts payable	(2,327)	(21,990)
Accrued liabilities	(40,526)	13,631
Other, net	(5,098)	(3,443)
Net cash provided by operating activities	435,355	432,242
Cash flows from investing activities
Acquisition of business, net of cash acquired	(15,782)	0
Additions to property, plant and equipment	(203,933)	(216,912)
Proceeds from disposition of assets	0	13
Proceeds from sales and maturities of securities	15,037	342,045
Purchase of securities	0	(117,332)
Settlements of derivative instruments	(1,174)	(290)
Net cash used for investing activities	(174,288)	7,524
Cash flows from financing activities
Dividends paid	(43,896)	(33,623)
Distributions to noncontrolling interests	(7,218)	0
Proceeds from exercise of stock options	831	4,187
Proceeds from issuance of notes payable	2,392	0
Repayment of notes payable	(4,299)	0
Repurchase of common stock for treasury	(62,804)
Windfall tax benefits from share-based payment arrangements	1,895	4,436
Net cash provided by financing activities	(113,099)	(25,000)
Effect of exchange rate changes on cash and cash equivalents	(2,000)	0
Net increase in cash and cash equivalents	145,968	414,766
Cash and cash equivalents at beginning of period	880,601	461,301
Cash and cash equivalents at end of period	$ 1,026,569	$ 876,067

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Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	$ 2,565	$ 2,289	$ 4,905	$ 4,511

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Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2015

Equity [Abstract]

Schedule of Stockholders Equity

Changes in stockholders' equity for the six months ended June 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	—		—			—		351,437			—			9,031			360,468
Other comprehensive income    (loss), net of income taxes:
Pension and other post-    retirement benefits    liability	—		—			—		—			752			—			752
Foreign currency    translation adjustments	—		—			—		—			(41,826		)	—			(41,826		)
Net unrealized holding    gains on investments	—		—			—		—			583			—			583
Common stock repurchased	—		(62,804		)	—		—			—			—			(62,804		)
Shares issued—stock-    based compensation	—		704			127		—			—			—			831
Stock-based compensation,    net of tax on stock options    exercised	—		—			6,800		—			—			—			6,800
Dividends paid	—		—			—		(43,896		)	—			—			(43,896		)
Distributions to noncontrolling    interests	—		—			—		—			—			(7,218		)	(7,218		)
Noncontrolling interest in    acquired business	—		—			—		—			—			1,597			1,597
Balances at June 30, 2015	$	1,347	$	(158,472	)	$	537,368	$	2,863,069		$	(119,924	)	$	293,787		$	3,417,175

	Common Stock		Common Stock, Held in Treasury			Additional Paid-in Capital		Retained Earnings			Accumulated Other Comprehensive  Income (Loss)			Total
Balances at December 31, 2013	$	1,346	$	(46,220	)	$	511,432	$	1,954,661		$	(2,616	)	$	2,418,603
Net income	—		—			—		327,475			—			327,475
Other comprehensive income (loss), net of    income taxes:
Pension and other post-retirement benefits    liability	—		—			—		—			255			255
Foreign currency translation adjustments	—		—			—		—			(90		)	(90		)
Net unrealized holding gains on    investments	—		—			—		—			2,319			2,319
Shares issued—stock-based compensation	1		1,039			3,147		—			—			4,187
Stock-based compensation, net of tax on stock    options exercised	—		—			8,947		—			—			8,947
Dividends paid	—		—			—		(33,623		)	—			(33,623		)
Balances at June 30, 2014	$	1,347	$	(45,181	)	$	523,526	$	2,248,513		$	(132	)	$	2,728,073

Schedule of Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive income (loss) by component for the six months ended June 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	(115		)	(41,826		)	3,015			(38,926		)
Amounts reclassified from accumulated other    comprehensive loss (income)	867			—			(2,432		)	(1,565		)
Net other comprehensive income (loss) for the period	752			(41,826		)	583			(40,491		)
Balances at June 30, 2015	$	(22,690	)	$	(98,050	)	$	816		$	(119,924	)

	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	(20		)	(90		)	3,096			2,986
Amounts reclassified from accumulated other    comprehensive loss	275			—			(777		)	(502		)
Net other comprehensive income (loss) for the period	255			(90		)	2,319			2,484
Balances at June 30, 2014	$	(6,441	)	$	3,814		$	2,495		$	(132	)

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 six months ended June 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 June 30,						Six Months Ended June 30,
		2015			2014			2015			2014
Amortization of pension and    other post-retirement items
Prior service costs	(1)	$	—		$	(87	)	$	—		$	(173	)
Net loss	(1)	(675		)	(139		)	(1,327		)	(272		)
		(675		)	(226		)	(1,327		)	(445		)
	Provision for income    taxes	235			86			460			170
		(440		)	(140		)	(867		)	(275		)
Net unrealized gains on    available-for-sale    investments
Realized gain on    available-for-sale    investments	Other income, net	3,795			1,237			3,795			1,212
	Provision for income    taxes	(1,363		)	(444		)	(1,363		)	(435		)
		2,432			793			2,432			777
Total reclassifications for    the period		$	1,992		$	653		$	1,565		$	502

_____________

(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.

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Income Taxes (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate	32.90%	34.90%
U.S. federal statutory income tax rate	35.00%	35.00%
Anticipated reductions to unrecognized tax benefits within next twelve months	$ 0
Income Tax Examination, Penalties and Interest Accrued	$ 0

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Supplemental Information

6 Months Ended

Jun. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Supplemental Information

Supplemental Information

Accrued Liabilities

Accrued liabilities were $251,680 and $276,118 at June 30, 2015 and December 31, 2014, respectively. Accrued rebates and accrued incentive compensation, which are components of accrued liabilities, were $30,428 and $34,278 at June 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 $162,777 and $174,859 at June 30, 2015 and December 31, 2014, respectively. Non-current pension obligation, which is a component of other liabilities, was $126,708 and $136,296 at June 30, 2015 and December 31, 2014, respectively. No other component of other liabilities was more than five percent of total liabilities.

Other Income, Net

	Three Months Ended June 30,					Six Months Ended June 30,
	2015			2014		2015			2014
Interest income	$	866		$	1,105	$	1,751		$	2,328
Dividend income	1,357			—		3,329			—
Foreign exchange currency (losses) gains, net	(500		)	3		1,871			(245		)
(Loss) income from equity method investments	(350		)	1,920		4,613			3,941
Impairment of equity method investment	(4,925		)	—		(4,925		)	—
Gain on acquisition and related expenses, net	20,430			—		20,430			—
Gain from sales of equity securities	3,795			—		3,795			—
Other	1,385			1,573		290			1,086
Other income, net	$	22,058		$	4,601	$	31,154		$	7,110

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Pension and Post-Retirement Benefit Costs (Tables)

6 Months Ended

Jun. 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 June 30,								Six Months Ended June 30,
	2015					2014			2015					2014
	U.S. Plans			Non-U.S. Plans		U.S. Plans			U.S. Plans			Non-U.S. Plans		U.S. Plans
Service cost	$	1		$	414	$	84		$	29		$	835	$	167
Interest cost	489			525		576			1,032			1,061		1,170
Expected return on plan assets	(705		)	—		(777		)	(1,524		)	—		(1,586		)
Amortization of prior service cost	—			—		74			—			—		148
Amortization of net loss	318			261		70			609			526		134
Net periodic benefit cost	$	103		$	1,200	$	27		$	146		$	2,422	$	33

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
	U.S. Plans		U.S. Plans		U.S. Plans		U.S. Plans
Service cost	$	6	$	5	$	11	$	11
Interest cost	149		181		299		362
Amortization of prior service cost	—		13		—		25
Amortization of net loss	96		69		192		138
Net periodic benefit cost	$	251	$	268	$	502	$	536

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Insurance Recovery (Notes)

6 Months Ended

Jun. 30, 2015

Insurance Recovery [Abstract]

Insurance Recovery

Insurance Recovery

During the second quarter 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. The Company recognized approximately $4,470 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.

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Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Weighted average common shares—basic	132,538,123	133,223,705	132,625,857	133,148,398
Plus incremental shares from: Assumed exercise of options	506,852	544,185	498,840	542,438
Weighted average common shares-diluted	133,044,975	133,767,890	133,124,697	133,690,836
Earnings per share: Basic (usd per share)	$ 1.55	$ 1.27	$ 2.65	$ 2.45
Earnings per share: Diluted (usd per share)	$ 1.54	$ 1.26	$ 2.64	$ 2.44

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Basis of Financial Statements

6 Months Ended

Jun. 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 June 30, 2015, its results of operations for the three and six months ended June 30, 2015 and 2014 and the changes in its cash position for the six months ended June 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.

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Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 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	134,679,064	134,679,064
Common stock, held in treasury	2,646,260	1,787,546

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Stock-Based Compensation

6 Months Ended

Jun. 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 $2,565 and $2,289 for the three months ended June 30, 2015 and 2014,respectively, and $4,905 and $4,511 for the six months ended June 30, 2015 and 2014, respectively.

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Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 29, 2015
Document Documentand Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
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		131,938,403

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Derivative Instruments

6 Months Ended

Jun. 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 six months ended June 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 six months ended June 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 June 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
		June 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	2,439	$	3,145
Commodity forward contracts	Deferred charges and    other assets, net	2,433		—
Total derivative assets		$	4,872	$	3,145

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		June 30, 2015		December 31, 2014
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	3,446	$	6,549
Commodity forward contracts	Other liabilities	3,047		3,559
Total derivative liabilities		$	6,493	$	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 June 30,				Six Months Ended June 30,
		2015		2014		2015		2014
Commodity forward contracts	Gross profit	$	595	$	240	$	4,836	$	(371	)

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

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Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,185,002	$ 998,576	$ 2,288,533	$ 2,026,252
Cost of sales	831,821	692,605	1,650,806	1,433,271
Gross profit	353,181	305,971	637,727	592,981
Selling, general and administrative expenses	57,807	39,183	113,073	78,138
Income from operations	295,374	266,788	524,654	514,843
Interest expense	(8,958)	(9,539)	(18,549)	(18,696)
Other income, net	22,058	4,601	31,154	7,110
Income before income taxes	308,474	261,850	537,259	503,257
Provision for (benefit from) income taxes	98,413	92,407	176,791	175,782
Equity in net income of subsidiaries	0	0	0	0
Net income	210,061	169,443	360,468	327,475
Net income attributable to noncontrolling interests	4,966	0	9,031	0
Net income attributable to Westlake Chemical Corporation	205,095	169,443	351,437	327,475
Comprehensive income (loss) attributable to Westlake Chemical Corporation	222,833	171,093	310,946	329,959
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	399	529	812	1,075
Income from operations	(399)	(529)	(812)	(1,075)
Interest expense	(10,569)	(9,535)	(21,321)	(18,690)
Other income, net	9,776	7,137	16,387	12,351
Income before income taxes	(1,192)	(2,927)	(5,746)	(7,414)
Provision for (benefit from) income taxes	(399)	(1,039)	(1,976)	(2,597)
Equity in net income of subsidiaries	205,888	171,331	355,207	332,292
Net income	205,095		351,437	327,475
Net income attributable to noncontrolling interests	0		0
Net income attributable to Westlake Chemical Corporation	205,095	169,443	351,437	327,475
Comprehensive income (loss) attributable to Westlake Chemical Corporation	222,833	171,093	310,946	329,959
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	990,434	879,842	1,901,365	1,724,184
Cost of sales	750,892	821,234	1,485,728	1,611,811
Gross profit	239,542	58,608	415,637	112,373
Selling, general and administrative expenses	42,682	31,066	86,366	60,351
Income from operations	196,860	27,542	329,271	52,022
Interest expense	(4)	(4)	(5)	(6)
Other income, net	(9,371)	965	(6,544)	1,213
Income before income taxes	187,485	28,503	322,722	53,229
Provision for (benefit from) income taxes	97,218	9,766	175,170	16,553
Equity in net income of subsidiaries	76,799	153,844	156,690	297,718
Net income	167,066		304,242	334,394
Net income attributable to noncontrolling interests	0		0
Net income attributable to Westlake Chemical Corporation	167,066	172,581	304,242	334,394
Comprehensive income (loss) attributable to Westlake Chemical Corporation	167,206	172,701	304,620	334,649
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Net sales	251,705	524,135	510,096	1,084,149
Cost of sales	157,177	277,589	319,341	605,289
Gross profit	94,528	246,546	190,755	478,860
Selling, general and administrative expenses	5,191	6,165	10,237	13,943
Income from operations	89,337	240,381	180,518	464,917
Interest expense	(856)	(4,105)	(2,232)	(7,696)
Other income, net	34	1,397	39	2,649
Income before income taxes	88,515	237,673	178,325	459,870
Provision for (benefit from) income taxes	(41)	83,829	426	162,152
Equity in net income of subsidiaries	0	0	0	0
Net income	88,556		177,899	297,718
Net income attributable to noncontrolling interests	0		0
Net income attributable to Westlake Chemical Corporation	88,556	153,844	177,899	297,718
Comprehensive income (loss) attributable to Westlake Chemical Corporation	88,556	153,844	177,899	297,718
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	250,365	11,753	496,007	20,870
Cost of sales	226,283	10,936	454,553	19,122
Gross profit	24,082	817	41,454	1,748
Selling, general and administrative expenses	14,506	1,423	25,777	2,769
Income from operations	9,576	(606)	15,677	(1,021)
Interest expense	(52)	0	(94)	0
Other income, net	24,142	(793)	26,375	(1,407)
Income before income taxes	33,666	(1,399)	41,958	(2,428)
Provision for (benefit from) income taxes	1,635	(149)	3,171	(326)
Equity in net income of subsidiaries	11,757	0	21,209	0
Net income	43,788		59,996	(2,102)
Net income attributable to noncontrolling interests	4,966		9,031
Net income attributable to Westlake Chemical Corporation	38,822	(1,250)	50,965	(2,102)
Comprehensive income (loss) attributable to Westlake Chemical Corporation	56,879	(442)	9,513	(2,192)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(307,502)	(417,154)	(618,935)	(802,951)
Cost of sales	(302,531)	(417,154)	(608,816)	(802,951)
Gross profit	(4,971)	0	(10,119)	0
Selling, general and administrative expenses	(4,971)	0	(10,119)	0
Income from operations	0	0	0	0
Interest expense	2,523	4,105	5,103	7,696
Other income, net	(2,523)	(4,105)	(5,103)	(7,696)
Income before income taxes	0	0	0	0
Provision for (benefit from) income taxes	0	0	0	0
Equity in net income of subsidiaries	(294,444)	(325,175)	(533,106)	(630,010)
Net income	(294,444)		(533,106)	(630,010)
Net income attributable to noncontrolling interests	0		0
Net income attributable to Westlake Chemical Corporation	(294,444)	(325,175)	(533,106)	(630,010)
Comprehensive income (loss) attributable to Westlake Chemical Corporation	$ (312,641)	$ (326,103)	$ (492,032)	$ (630,175)

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Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Net sales	$ 1,185,002	$ 998,576	$ 2,288,533	$ 2,026,252
Cost of sales	831,821	692,605	1,650,806	1,433,271
Gross profit	353,181	305,971	637,727	592,981
Selling, general and administrative expenses	57,807	39,183	113,073	78,138
Income from operations	295,374	266,788	524,654	514,843
Other income (expense)
Interest expense	(8,958)	(9,539)	(18,549)	(18,696)
Other income, net	22,058	4,601	31,154	7,110
Income before income taxes	308,474	261,850	537,259	503,257
Provision for income taxes	98,413	92,407	176,791	175,782
Net income	210,061	169,443	360,468	327,475
Net income attributable to noncontrolling interests	4,966	0	9,031	0
Net income attributable to Westlake Chemical Corporation	$ 205,095	$ 169,443	$ 351,437	$ 327,475
Earnings per common share attributable to Westlake Chemical Corporation
Basic (usd per share)	$ 1.55	$ 1.27	$ 2.65	$ 2.45
Diluted (usd per share)	$ 1.54	$ 1.26	$ 2.64	$ 2.44
Weighted average shares outstanding:
Basic	132,538,123	133,223,705	132,625,857	133,148,398
Diluted	133,044,975	133,767,890	133,124,697	133,690,836
Dividends per common share	$ 0.1650	$ 0.1260	$ 0.3300	$ 0.2520

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Other Assets

6 Months Ended

Jun. 30, 2015

Other Assets [Abstract]

Other Assets

Other Assets

Amortization expense on intangible and other assets of $9,578 and $9,008 is included in the consolidated statements of operations for the three months ended June 30, 2015 and 2014, respectively. Amortization expense on intangible and other assets of $19,062 and $17,284 is included in the consolidated statements of operations for the six months ended June 30, 2015 and 2014, respectively.

Goodwill

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

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Property, Plant and Equipment

6 Months Ended

Jun. 30, 2015

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

As of June 30, 2015, the Company had property, plant and equipment, net totaling $2,855,508. 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 $51,263 and $39,859 is included in cost of sales in the consolidated statements of operations for the three months ended June 30, 2015 and 2014, respectively. Depreciation expense on property, plant and equipment of $100,921 and $77,920 is included in cost of sales in the consolidated statements of operations for the six months ended June 30, 2015 and 2014, respectively.

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Acquisition

6 Months Ended

Jun. 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, 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, 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 six months ended June 30, 2015. The acquisition-related costs recognized in the consolidated statements of operations for the three and six months ended June 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 six months ended June 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.

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Fair Value Measurements

6 Months Ended

Jun. 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:

	June 30, 2015
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	3,958		$	914		$	4,872
Risk management liabilities—Commodity forward contracts	(1,825		)	(4,668		)	(6,493		)
Marketable securities
Available-for-sale securities	5,074			—			5,074
	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.

There were no transfers in or out of Levels 1 and 2 of the fair value hierarchy for the six months ended June 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.

	June 30, 2015				December 31, 2014
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	249,167	$	251,118	$	249,108	$	248,630
6 ½% senior notes due 2029	100,000		119,018		100,000		116,384
6 ¾% senior notes due 2032	250,000		277,375		250,000		285,545
6 ½% GO Zone Senior Notes Due 2035	89,000		104,498		89,000		106,504
6 ½% IKE Zone Senior Notes Due 2035	65,000		75,485		65,000		77,784
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

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Stockholders Equity

6 Months Ended

Jun. 30, 2015

Equity [Abstract]

Stockholders' Equity

Stockholders' Equity

Changes in stockholders' equity for the six months ended June 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	—		—			—		351,437			—			9,031			360,468
Other comprehensive income    (loss), net of income taxes:
Pension and other post-    retirement benefits    liability	—		—			—		—			752			—			752
Foreign currency    translation adjustments	—		—			—		—			(41,826		)	—			(41,826		)
Net unrealized holding    gains on investments	—		—			—		—			583			—			583
Common stock repurchased	—		(62,804		)	—		—			—			—			(62,804		)
Shares issued—stock-    based compensation	—		704			127		—			—			—			831
Stock-based compensation,    net of tax on stock options    exercised	—		—			6,800		—			—			—			6,800
Dividends paid	—		—			—		(43,896		)	—			—			(43,896		)
Distributions to noncontrolling    interests	—		—			—		—			—			(7,218		)	(7,218		)
Noncontrolling interest in    acquired business	—		—			—		—			—			1,597			1,597
Balances at June 30, 2015	$	1,347	$	(158,472	)	$	537,368	$	2,863,069		$	(119,924	)	$	293,787		$	3,417,175

	Common Stock		Common Stock, Held in Treasury			Additional Paid-in Capital		Retained Earnings			Accumulated Other Comprehensive  Income (Loss)			Total
Balances at December 31, 2013	$	1,346	$	(46,220	)	$	511,432	$	1,954,661		$	(2,616	)	$	2,418,603
Net income	—		—			—		327,475			—			327,475
Other comprehensive income (loss), net of    income taxes:
Pension and other post-retirement benefits    liability	—		—			—		—			255			255
Foreign currency translation adjustments	—		—			—		—			(90		)	(90		)
Net unrealized holding gains on    investments	—		—			—		—			2,319			2,319
Shares issued—stock-based compensation	1		1,039			3,147		—			—			4,187
Stock-based compensation, net of tax on stock    options exercised	—		—			8,947		—			—			8,947
Dividends paid	—		—			—		(33,623		)	—			(33,623		)
Balances at June 30, 2014	$	1,347	$	(45,181	)	$	523,526	$	2,248,513		$	(132	)	$	2,728,073

Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive income (loss) by component for the six months ended June 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	(115		)	(41,826		)	3,015			(38,926		)
Amounts reclassified from accumulated other    comprehensive loss (income)	867			—			(2,432		)	(1,565		)
Net other comprehensive income (loss) for the period	752			(41,826		)	583			(40,491		)
Balances at June 30, 2015	$	(22,690	)	$	(98,050	)	$	816		$	(119,924	)

	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	(20		)	(90		)	3,096			2,986
Amounts reclassified from accumulated other    comprehensive loss	275			—			(777		)	(502		)
Net other comprehensive income (loss) for the period	255			(90		)	2,319			2,484
Balances at June 30, 2014	$	(6,441	)	$	3,814		$	2,495		$	(132	)

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 six months ended June 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 June 30,						Six Months Ended June 30,
		2015			2014			2015			2014
Amortization of pension and    other post-retirement items
Prior service costs	(1)	$	—		$	(87	)	$	—		$	(173	)
Net loss	(1)	(675		)	(139		)	(1,327		)	(272		)
		(675		)	(226		)	(1,327		)	(445		)
	Provision for income    taxes	235			86			460			170
		(440		)	(140		)	(867		)	(275		)
Net unrealized gains on    available-for-sale    investments
Realized gain on    available-for-sale    investments	Other income, net	3,795			1,237			3,795			1,212
	Provision for income    taxes	(1,363		)	(444		)	(1,363		)	(435		)
		2,432			793			2,432			777
Total reclassifications for    the period		$	1,992		$	653		$	1,565		$	502

_____________

(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.

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

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Accounts and Notes Payable

6 Months Ended

Jun. 30, 2015

Accounts and Notes Payable [Abstract]

Accounts and Notes Payable

Accounts and Notes Payable

Accounts and notes payable consist of the following:

	June 30, 2015		December 31, 2014
Accounts payable	$	263,803	$	261,062
Notes payable to banks	19,175		—
Accounts and notes payable	$	282,978	$	261,062

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Long-Term Debt

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Long-Term Debt

Long-Term Debt

Long-term debt consists of the following:

	June 30, 2015		December 31, 2014
3.60% senior notes due 2022	$	249,167	$	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	$	764,056	$	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 June 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 June 30, 2015, the Company had outstanding letters of credit totaling $29,670 and borrowing availability of $370,330 under the revolving credit facility.

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Pension and Post-Retirement Benefit Costs

6 Months Ended

Jun. 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 June 30,								Six Months Ended June 30,
	2015					2014			2015					2014
	U.S. Plans			Non-U.S. Plans		U.S. Plans			U.S. Plans			Non-U.S. Plans		U.S. Plans
Service cost	$	1		$	414	$	84		$	29		$	835	$	167
Interest cost	489			525		576			1,032			1,061		1,170
Expected return on plan assets	(705		)	—		(777		)	(1,524		)	—		(1,586		)
Amortization of prior service cost	—			—		74			—			—		148
Amortization of net loss	318			261		70			609			526		134
Net periodic benefit cost	$	103		$	1,200	$	27		$	146		$	2,422	$	33

The Company made no contribution to the U.S. salaried pension plan in the first six months of 2015. The Company contributed $965 to the U.S. salaried pension plan in the first six months of 2014. The Company contributed $349 and $580 to the U.S. wage pension plan in the first six 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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
	U.S. Plans		U.S. Plans		U.S. Plans		U.S. Plans
Service cost	$	6	$	5	$	11	$	11
Interest cost	149		181		299		362
Amortization of prior service cost	—		13		—		25
Amortization of net loss	96		69		192		138
Net periodic benefit cost	$	251	$	268	$	502	$	536

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Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 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	$ 249,167	$ 249,108
3.60% Senior Notes Due 2022 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 251,118	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	$ 119,018	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	$ 277,375	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	$ 104,498	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	$ 75,485	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

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Earnings per Share (Additional Information) (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Number of options excluded from computation of diluted earnings per share	330,315	134,938	285,933	102,480

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Fair Value Measurements (Summary of Assets and Liabilities Accounted at Fair Value on Recurring Basis) (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 5,074	$ 15,414
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	5,074	15,414
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	4,872	3,145
Risk management liabilities - Commodity forward contracts	(6,493)	(10,108)
Forward Contracts [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	3,958	3,143
Risk management liabilities - Commodity forward contracts	(1,825)	0
Forward Contracts [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk management assets - Commodity forward contracts	914	2
Risk management liabilities - Commodity forward contracts	$ (4,668)	$ (10,108)

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Long-Term Debt (Tables)

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Schedule Of Long-Term Debt

Long-term debt consists of the following:

	June 30, 2015		December 31, 2014
3.60% senior notes due 2022	$	249,167	$	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	$	764,056	$	763,997

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Accounts and Notes Payable (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accounts and Notes Payable [Abstract]
Accounts payable	$ 263,803	$ 261,062
Notes payable to banks	19,175	0
Accounts and notes payable	$ 282,978	$ 261,062

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Earnings per Share

6 Months Ended

Jun. 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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Net income attributable to    Westlake Chemical Corporation	$	205,095		$	169,443		$	351,437		$	327,475
Less:
Net income attributable to participating securities	(253		)	(360		)	(457		)	(746		)
Net income attributable to common shareholders	$	204,842		$	169,083		$	350,980		$	326,729

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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Weighted average common shares—basic	132,538,123		133,223,705		132,625,857		133,148,398
Plus incremental shares from:
Assumed exercise of options	506,852		544,185		498,840		542,438
Weighted average common shares—diluted	133,044,975		133,767,890		133,124,697		133,690,836
Earnings per common share attributable to    Westlake Chemical Corporation:
Basic	$	1.55	$	1.27	$	2.65	$	2.45
Diluted	$	1.54	$	1.26	$	2.64	$	2.44

Excluded from the computation of diluted earnings per share are options to purchase 330,315 and 134,938 shares of common stock for the three months ended June 30, 2015 and 2014, respectively, and 285,933 and 102,480 shares of common stock for the six months ended June 30, 2015 and 2014, respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive.

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Segment Information

6 Months Ended

Jun. 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 June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Net external sales
Olefins
Polyethylene	$	450,482		$	475,503		$	859,914		$	962,647
Styrene, feedstock and other	170,396			223,550			344,041			459,204
Total Olefins	620,878			699,053			1,203,955			1,421,851
Vinyls
PVC, caustic soda and other	429,878			168,762			846,866			359,289
Building products	134,246			130,761			237,712			245,112
Total Vinyls	564,124			299,523			1,084,578			604,401
	$	1,185,002		$	998,576		$	2,288,533		$	2,026,252
Intersegment sales
Olefins	$	26,641		$	34,782		$	50,103		$	91,635
Vinyls	387			331			757			674
	$	27,028		$	35,113		$	50,860		$	92,309
Income (loss) from operations
Olefins	$	220,938		$	238,657		$	412,041		$	510,990
Vinyls	87,966			38,129			135,052			17,015
Corporate and other	(13,530		)	(9,998		)	(22,439		)	(13,162		)
	$	295,374		$	266,788		$	524,654		$	514,843
Depreciation and amortization
Olefins	$	27,623		$	26,721		$	54,562		$	53,368
Vinyls	32,599			21,623			64,183			40,791
Corporate and other	118			158			236			315
	$	60,340		$	48,502		$	118,981		$	94,474
Other income (expense), net
Olefins	$	(104	)	$	1,199		$	2,448		$	2,653
Vinyls	1,413			(213		)	6,916			(247		)
Corporate and other	20,749			3,615			21,790			4,704
	$	22,058		$	4,601		$	31,154		$	7,110
Provision for (benefit from) income taxes
Olefins	$	74,212		$	83,502		$	140,669		$	177,052
Vinyls	26,653			10,430			39,458			360
Corporate and other	(2,452		)	(1,525		)	(3,336		)	(1,630		)
	$	98,413		$	92,407		$	176,791		$	175,782
Capital expenditures
Olefins	$	81,534		$	43,448		$	136,835		$	72,522
Vinyls	24,569			62,262			61,425			143,382
Corporate and other	2,007			461			5,673			1,008
	$	108,110		$	106,171		$	203,933		$	216,912

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Income from operations	$	295,374		$	266,788		$	524,654		$	514,843
Interest expense	(8,958		)	(9,539		)	(18,549		)	(18,696		)
Other income, net	22,058			4,601			31,154			7,110
Income before income taxes	$	308,474		$	261,850		$	537,259		$	503,257

	June 30, 2015		December 31, 2014
Total assets
Olefins	$	1,844,391	$	1,785,895
Vinyls	2,656,936		2,618,646
Corporate and other	909,683		809,449
	$	5,411,010	$	5,213,990

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Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, plant and equipment	$ 2,855,508		$ 2,855,508		$ 2,757,557
Depreciation expense on property, plant and equipment	$ 51,263	$ 39,859	$ 100,921	$ 77,920

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Acquisition (Tables)

6 Months Ended

Jun. 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.

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Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 210,061	$ 169,443	$ 360,468	$ 327,475
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	186	31	186	31
Amortization of benefits liability	675	226	1,327	445
Income tax provision on pension and other post-retirement benefits liability	(164)	(75)	(389)	(159)
Foreign currency translation adjustments	17,872	808	(41,826)	(90)
Available-for-sale investments
Unrealized holding gains on investments	3,077	2,364	4,703	4,831
Reclassification of net realized gain to net income	(3,795)	(1,237)	(3,795)	(1,212)
Income tax benefit (provision) on available- for-sale investments	259	(405)	(325)	(1,300)
Other comprehensive income (loss)	17,738	1,650	(40,491)	2,484
Comprehensive income	227,799	171,093	319,977	329,959
Comprehensive income attributable to noncontrolling interests, net of tax	4,966	0	9,031	0
Comprehensive income attributable to Westlake Chemical Corporation	$ 222,833	$ 171,093	$ 310,946	$ 329,959

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Inventories

6 Months Ended

Jun. 30, 2015

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories consist of the following:

	June 30, 2015		December 31, 2014
Finished products	$	280,317	$	300,909
Feedstock, additives and chemicals	134,369		158,635
Materials and supplies	71,611		66,232
Inventories	$	486,297	$	525,776

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Pension and Post-Retirement Benefit Costs (Additional Information) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Salaried Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 0	$ 965
Estimated future employer contributions for next fiscal year	0
Wage Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	349	$ 580
Estimated future employer contributions for next fiscal year	$ 0

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Supplemental Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Accrued Liabilities [Abstract]
Accrued liabilities	$ 251,680		$ 251,680		$ 276,118
Accrued rebates	30,428		30,428		49,900
Accrued incentive compensation	34,278		34,278		37,626
Other Liabilities [Abstract]
Other liabilities	162,777		162,777		174,859
Non-current pension obligation	126,708		126,708		$ 136,296
Other Income and Expenses [Abstract]
Interest income	866	$ 1,105	1,751	$ 2,328
Dividend income	1,357	0	3,329	0
Foreign exchange currency (losses) gains, net	(500)	3	1,871	(245)
(Loss) income from equity method investments	(350)	1,920	4,613	3,941
Impairment of equity method investment	(4,925)	0	(4,925)	0
Gain on acquisition and related expenses, net	20,430	0	20,430	0
Gain from sales of equity securities	3,795	0	3,795	0
Other	1,385	1,573	290	1,086
Other income, net	$ 22,058	$ 4,601	$ 31,154	$ 7,110

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Subsequent Events

6 Months Ended

Jun. 30, 2015

Subsequent Events [Abstract]

Subsequent Events

Subsequent Events

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

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Segment Information (Additional Information) (Detail)	3 Months Ended
	Jun. 30, 2015 Segment
Segment Reporting [Abstract]
Number of segments	2

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Fair Value Measurements (Tables)

6 Months Ended

Jun. 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:

	June 30, 2015
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	3,958		$	914		$	4,872
Risk management liabilities—Commodity forward contracts	(1,825		)	(4,668		)	(6,493		)
Marketable securities
Available-for-sale securities	5,074			—			5,074
	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.

	June 30, 2015				December 31, 2014
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	249,167	$	251,118	$	249,108	$	248,630
6 ½% senior notes due 2029	100,000		119,018		100,000		116,384
6 ¾% senior notes due 2032	250,000		277,375		250,000		285,545
6 ½% GO Zone Senior Notes Due 2035	89,000		104,498		89,000		106,504
6 ½% IKE Zone Senior Notes Due 2035	65,000		75,485		65,000		77,784
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

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Income Taxes

6 Months Ended

Jun. 30, 2015

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

The effective income tax rate was 32.9% for the six months ended June 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. and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 34.9% for the six months ended June 30, 2014. The effective income tax rate for the 2014 period was below the U.S. federal statutory rate of 35.0% primarily due to state tax credits and the domestic manufacturing deduction, mostly offset by state income taxes.

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