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 March 31, 2013

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 April 30, 2013 was 66,777,348.

INDEX

Item	Page
PART I. FINANCIAL INFORMATION
1) Financial Statements	1
2) Management's Discussion and Analysis of Financial Condition and Results of Operations	22
3) Quantitative and Qualitative Disclosures about Market Risk	30
4) Controls and Procedures	30
PART II. OTHER INFORMATION
1) Legal Proceedings	31
1A) Risk Factors	31
2) Unregistered Sales of Equity Securities and Use of Proceeds	31
6) Exhibits	32

PART I. FINANCIAL INFORMATION

Item 1. Financial Statements

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED BALANCE SHEETS

(Unaudited)

	March 31, 2013			December 31, 2012
	(in thousands of dollars, except par values and share amounts)
ASSETS
Current assets
Cash and cash equivalents	$	777,887		$	790,078
Marketable securities	94,903			124,873
Accounts receivable, net	407,580			400,159
Inventories	408,074			399,298
Prepaid expenses and other current assets	14,536			14,700
Deferred income taxes	22,298			22,305
Total current assets	1,725,278			1,751,413
Property, plant and equipment, net	1,629,309			1,510,048
Equity investments	43,914			43,736
Other assets, net
Intangible assets, net	48,108			48,292
Deferred charges and other assets, net	112,616			58,707
Total other assets, net	160,724			106,999
Total assets	$	3,559,225		$	3,412,196
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities
Accounts payable	$	232,061		$	217,050
Accrued liabilities	167,754			181,460
Total current liabilities	399,815			398,510
Long-term debt	763,790			763,761
Deferred income taxes	355,975			326,290
Other liabilities	49,854			51,379
Total liabilities	1,569,434			1,539,940
Commitments and contingencies (Notes 7 and 15)
Stockholders' equity
Preferred stock, $0.01 par value, 50,000,000 shares authorized;    no shares issued and outstanding	—			—
Common stock, $0.01 par value, 150,000,000 shares authorized;    67,232,590 and 67,187,224 shares issued at March 31, 2013    and December 31, 2012, respectively	672			672
Common stock, held in treasury, at cost; 284,493 shares    at March 31, 2013 and December 31, 2012	(13,302		)	(13,302		)
Additional paid-in capital	503,187			496,254
Retained earnings	1,510,266			1,399,472
Accumulated other comprehensive loss	(11,032		)	(10,840		)
Total stockholders' equity	1,989,791			1,872,256
Total liabilities and stockholders' equity	$	3,559,225		$	3,412,196

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

1

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited)

	Three Months Ended March 31,
	2013			2012
	(in thousands of dollars, except per share data and share amounts)
Net sales	$	864,647		$	1,034,867
Cost of sales	636,838			862,230
Gross profit	227,809			172,637
Selling, general and administrative expenses	33,754			27,012
Income from operations	194,055			145,625
Other income (expense)
Interest expense	(6,281		)	(12,177		)
Other income, net	3,519			1,347
Income before income taxes	191,293			134,795
Provision for income taxes	67,946			46,982
Net income	$	123,347		$	87,813
Earnings per share:
Basic	$	1.84		$	1.32
Diluted	$	1.84		$	1.31
Weighted average shares outstanding:
Basic	66,625,536			66,109,297
Diluted	66,908,869			66,558,517
Dividends per common share	$	0.1875		$	0.0738

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 March 31,
	2013			2012
	(in thousands of dollars)
Net income	$	123,347		$	87,813
Other comprehensive income (loss)
Pension and other post-retirement benefits liability
Amortization of benefits liability	614			578
Income tax provision on pension and other    post-retirement benefits liability	(236		)	(222		)
Foreign currency translation adjustments	(570		)	512
Available-for-sale investments
Unrealized holding gains on investments	—			25,473
Income tax provision on unrealized    holding gains	—			(9,135		)
Other comprehensive (loss) income	(192		)	17,206
Comprehensive income	$	123,155		$	105,019

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

3

WESTLAKE CHEMICAL CORPORATION

CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

	Three Months Ended March 31,
	2013			2012
	(in thousands of dollars)
Cash flows from operating activities
Net income	$	123,347		$	87,813
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	35,356			35,394
Provision for (recovery of) doubtful accounts	393			(155		)
Amortization of debt issuance costs	365			400
Stock-based compensation expense	1,499			1,651
Loss from disposition of fixed assets	2,387			481
Deferred income taxes	29,466			791
Windfall tax benefits from share-based payment arrangements	(3,844		)	(4,481		)
Equity in (income) loss of joint ventures	(178		)	702
Changes in operating assets and liabilities
Accounts receivable	(7,917		)	(37,720		)
Inventories	(8,776		)	68,372
Prepaid expenses and other current assets	(2,077		)	(1,611		)
Accounts payable	14,733			(28,138		)
Accrued liabilities	(14,670		)	(21,647		)
Other, net	(53,832		)	3,724
Net cash provided by operating activities	116,252			105,576
Cash flows from investing activities
Additions to property, plant and equipment	(150,784		)	(64,902		)
Proceeds from disposition of assets	2			3
Proceeds from repayment of loan to affiliate	167			167
Proceeds from sales and maturities of securities	124,873			—
Purchase of securities	(94,903		)	(2,961		)
Settlements of derivative instruments	(679		)	511
Net cash used for investing activities	(121,324		)	(67,182		)
Cash flows from financing activities
Dividends paid	(12,553		)	(4,914		)
Proceeds from exercise of stock options	1,590			480
Utilization of restricted cash	—			30,800
Windfall tax benefits from share-based payment arrangements	3,844			4,481
Net cash (used for) provided by financing activities	(7,119		)	30,847
Net (decrease) increase in cash and cash equivalents	(12,191		)	69,241
Cash and cash equivalents at beginning of period	790,078			825,901
Cash and cash equivalents at end of period	$	777,887		$	895,142

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 have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2012 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, 2012 (the "2012 Form 10-K"), filed with the SEC on February 22, 2013. 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, 2012.

In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of March 31, 2013, its results of operations for the three months ended March 31, 2013 and 2012 and the changes in its cash position for the three months ended March 31, 2013 and 2012.

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, 2013 or any other interim period. The preparation of financial statements in conformity with generally accepted accounting principles in the United States 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.

Revisions

The consolidated statement of cash flows for the three months ended March 31, 2012 has been revised to correct the presentation of windfall tax benefits from share-based compensation of $4,481 in financing activities, instead of operating activities. This revision also impacts the consolidated statements of cash flows for the six months ended June 30, 2012 and nine months ended September 30, 2012 by $6,468 and $7,792, respectively, as well as the years ended December 31, 2010, 2011 and 2012 by $326, $3,361 and $11,967, respectively. The Company has determined that these revisions were immaterial to the Company's previously issued financial statements.

Recent Accounting Pronouncements

Disclosures about Offsetting Assets and Liabilities

In December 2011, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on disclosures for offsetting assets and liabilities. The new accounting guidance requires companies to disclose both gross and net information about (1) instruments and transactions eligible for offset in the statement of financial position, and (2) instruments and transactions subject to an agreement similar to a master netting arrangement. The FASB issued another accounting standards update clarifying the scope of the assets and liabilities offset disclosure requirements in January 2013. The effective date of the disclosure requirements remains unchanged. The Company adopted the new guidance as of January 1, 2013, and the adoption did not have an impact on the Company's consolidated financial position, results of operations or cash flows.

Testing Indefinite-Lived Intangible Assets for Impairment

In July 2012, the FASB issued an accounting standards update to simplify how entities test indefinite-lived intangible assets for impairment and to improve consistency in impairment testing guidance among long-lived asset categories. The new accounting guidance provides an entity with an option to first assess qualitative factors to determine whether it is more likely than not that an indefinite-lived intangible asset is impaired as a basis for determining whether it is necessary to perform the quantitative impairment test under current accounting guidance. If an entity concludes that it is not more likely than not that the indefinite-lived intangible asset is impaired, then the entity is not required to take further action. However, if an entity concludes otherwise, then it is required to determine the fair value of the indefinite-lived intangible asset and perform the quantitative impairment test by comparing the fair value with the carrying amount in accordance with current accounting guidance. Also under this new accounting guidance, an entity has the option to bypass the qualitative assessment for any indefinite-lived intangible asset in any period and proceed directly to performing the quantitative impairment test, but may resume performing the qualitative assessment in any subsequent period. The Company adopted the new indefinite-lived

5

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

intangible assets test guidance as of January 1, 2013, and the adoption did not have a material impact on the Company's consolidated financial position, results of operations or cash flows.

Reclassifications Out of Accumulated Other Comprehensive Income

In February 2013, the FASB issued an accounting standards update on reporting items reclassified out of accumulated other comprehensive income. The new accounting guidance requires companies to present either parenthetically on the face of the financial statements or in the notes, significant amounts reclassified from each component of accumulated other comprehensive income and the income statement line items affected by the reclassification, with certain exceptions. The Company adopted the new guidance as of January 1, 2013, and the adoption did not have an impact on the Company's consolidated financial position, results of operations or cash flows.

2. Current Marketable Securities

The Company owned current marketable securities of $94,903 and $124,873 at March 31, 2013 and December 31, 2012, respectively, consisting of short-term corporate debt securities with maturities exceeding three months at the date of acquisition. These debt securities are classified as held-to-maturity and are carried at amortized cost, which approximates their fair value.

3. Accounts Receivable

Accounts receivable consist of the following:

	March 31, 2013			December 31, 2012
Trade customers	$	384,413		$	388,949
Affiliates	297			258
Allowance for doubtful accounts	(11,562		)	(11,172		)
	373,148			378,035
Federal and state taxes	22,480			4,011
Other	11,952			18,113
Accounts receivable, net	$	407,580		$	400,159

4. Inventories

Inventories consist of the following:

	March 31, 2013		December 31, 2012
Finished products	$	198,639	$	200,940
Feedstock, additives and chemicals	154,304		143,912
Materials and supplies	55,131		54,446
Inventories	$	408,074	$	399,298

5. Property, Plant and Equipment

As of March 31, 2013, the Company had property, plant and equipment, net totaling $1,629,309. 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 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.

6

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

Depreciation expense on property, plant and equipment of $30,920 and $30,171 is included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2013 and 2012, respectively.

6. Other Assets

Amortization expense on intangible and other assets of $4,801 and $5,623 is included in the consolidated statements of operations for the three months ended March 31, 2013 and 2012, respectively.

7. Long-Term Debt

Long-term debt consists of the following:

	March 31, 2013		December 31, 2012
3.60% senior notes due 2022	$	248,901	$	248,872
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	$	763,790	$	763,761

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 $150,000) under certain circumstances if lenders agree to commit to such an increase. At March 31, 2013, 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 1.75% to 2.25% or a base rate plus a spread ranging from 0.25% to 0.75%. The revolving credit facility also requires an unused commitment fee of 0.375% 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 September 16, 2016. As of March 31, 2013, the Company had outstanding letters of credit totaling $16,214 and borrowing availability of $383,786 under the revolving credit facility.

8. Stock-Based Compensation

Under the Westlake Chemical Corporation 2004 Omnibus Incentive Plan (the "2004 Plan"), all employees and nonemployee 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 2004 Plan. At the discretion of the administrator of the 2004 Plan, employees and nonemployee 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 2004 Plan was $1,499 and $1,651 for the three months ended March 31, 2013 and 2012, respectively.

9. 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, were included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2013 and 2012. As of March 31, 2013, the Company had 32,130,000 gallons of feedstock forward contracts designated as fair value hedges.

7

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

Gains and losses from changes in the fair value of derivative instruments that are not designated as hedging instruments were included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2013 and 2012.

The exposure on commodity derivatives used for price risk management includes the risk that the counterparty will not pay if the market declines below the established fixed price. In such case, the Company would lose the benefit of the derivative differential on the volume of the commodities covered. In any event, the Company would continue to receive the market price on the actual volume hedged. The Company also bears the risk that it could lose the benefit of market improvements over the fixed derivative price for the term and volume of the derivative instruments (as such improvements would accrue to the benefit of the counterparty).

The fair values of derivative instruments in the Company's consolidated balance sheets were as follows:

	Derivative Assets
	Balance Sheet Location	Fair Value as of
		March 31, 2013		December 31, 2012
Designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	8,299	$	13,032
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	1,903		1,395
Total derivative assets		$	10,202	$	14,427

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		March 31, 2013		December 31, 2012
Designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	—	$	399
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	9,843		13,295
Total derivative liabilities		$	9,843	$	13,694

The following tables reflect the impact of derivative instruments designated as fair value hedges and the related hedged item on the Company's consolidated statements of operations. For the three months ended March 31, 2013 and 2012, there was no material ineffectiveness with regard to the Company's qualifying fair value hedges.

Derivatives in Fair Value    Hedging Relationships	Location of Gain (Loss) Recognized in  Income on Derivative	Three Months Ended March 31,
		2013			2012
Commodity forward contracts	Cost of sales	$	(1,643	)	$	10,463
Hedged Items in Fair Value    Hedging Relationships	Location of Gain (Loss) Recognized in  Income on Hedged Items	Three Months Ended March 31,
		2013			2012
Firm commitment designated as the hedged item	Cost of sales	$	1,395		$	(11,664	)

The impact of derivative instruments that have not been designated as hedges on the Company's consolidated statements of operations were as follows:

Derivatives Not Designated as    Hedging Instruments	Location of Gain (Loss) Recognized in  Income on Derivative	Three Months Ended March 31,
		2013		2012
Commodity forward contracts	Cost of sales	$	7,335	$	560

See Note 10 for the fair value of the Company's derivative instruments.

8

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

Disclosure about Offsetting Asset and Liability Derivatives

Certain of the Company's derivative instruments are executed under an International Swaps and Derivatives Association ("ISDA") Master Agreement, which permit the Company and a counterparty to aggregate the amounts owed by each party under multiple transactions and replace them with a single net amount payable by one party to the other. The following tables present the Company's derivative assets and derivative liabilities reported on the consolidated balance sheets and derivative assets and derivative liabilities subject to enforceable master netting arrangements.

	Derivative Assets
	March 31, 2013		December 31, 2012
Derivative assets subject to enforceable master netting arrangements	$	—	$	—
Derivative assets not subject to enforceable master netting arrangements	9,057		13,032
Total derivative assets	$	9,057	$	13,032

	March 31, 2013							December 31, 2012
Offsetting of Derivative Assets	Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Assets Presented in the Consolidated Balance Sheet		Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Assets Presented in the Consolidated Balance Sheet
Commodity forward contracts	$	1,145	$	(1,145	)	$	—	$	1,395	$	(1,395	)	$	—

	Derivative Liabilities
	March 31, 2013		December 31, 2012
Derivative liabilities subject to enforceable master netting arrangements	$	697	$	1,774
Derivative liabilities not subject to enforceable master netting arrangements	8,001		10,525
Total derivative liabilities	$	8,698	$	12,299

	March 31, 2013							December 31, 2012
Offsetting of Derivative Liabilities	Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Liabilities Presented in the Consolidated Balance Sheet
Commodity forward contracts	$	1,842	$	(1,145	)	$	697	$	3,169	$	(1,395	)	$	1,774

	March 31, 2013						December 31, 2012
Derivative Liabilities by Counterparty	Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts Not Offset in the Consolidated Balance Sheet		Net Amount		Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts Not Offset in the Consolidated Balance Sheet		Net Amount
Counterparty A	$	463	$	—	$	463	$	1,128	$	—	$	1,128
Counterparty B	234		—		234		646		—		646
Total	$	697	$	—	$	697	$	1,774	$	—	$	1,774

9

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

10. Fair Value Measurements

The Company reports certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Under the accounting guidance for fair value measurements, inputs used to measure fair value are classified in one of three levels:

Level 1: Quoted market prices in active markets for identical assets or liabilities.

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data.

Level 3: Unobservable inputs that are not corroborated by market data.

The following tables summarize, by level within the fair value hierarchy, the Company's assets and liabilities that were accounted for at fair value on a recurring basis:

	March 31, 2013
	Level 1		Level 2			Total
Derivative instruments
Risk management assets - Commodity forward contracts	$	1,145	$	9,057		$	10,202
Risk management liabilities - Commodity forward contracts	—		(9,843		)	(9,843		)
Firm commitments
Hedged portion of firm commitment	—		(8,299		)	(8,299		)
	December 31, 2012
	Level 1		Level 2			Total
Derivative instruments
Risk management assets - Commodity forward contracts	$	1,395	$	13,032		$	14,427
Risk management liabilities - Commodity forward contracts	—		(13,694		)	(13,694		)
Firm commitments
Hedged portion of firm commitment	—		399			399
Hedged portion of firm commitment	—		(13,032		)	(13,032		)

The Level 2 measurements are derived using forward curves supplied by industry recognized and unrelated third-party services. There were no transfers in and out of Levels 1 and 2 of the fair value hierarchy for the three months ended March 31, 2013 and 2012.

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 payable and long-term debt, all of which are recorded at carrying value. Further, the Company has current marketable securities that are carried at amortized cost. The amounts reported in the consolidated balance sheets for cash and cash equivalents, current marketable securities, accounts receivable, net and accounts 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.

10

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

	March 31, 2013				December 31, 2012
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	248,901	$	252,273	$	248,872	$	251,125
6 ½% senior notes due 2029	100,000		115,999		100,000		119,738
6 ¾% senior notes due 2032	250,000		286,235		250,000		283,168
6 ½% GO Zone Senior Notes Due 2035	89,000		100,367		89,000		102,095
6 ½% IKE Zone Senior Notes Due 2035	65,000		73,302		65,000		74,564
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

11. Income Taxes

The effective income tax rate was 35.5% for the three months ended March 31, 2013. The effective income tax rate for the 2013 period was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction. The effective income tax rate was 34.9% for the three months ended March 31, 2012. The effective income tax rate for the 2012 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 was no material change to the total gross unrecognized tax benefits for the three months ended March 31, 2013. Management anticipates reductions to the total amount of unrecognized tax benefits of an additional $621 within the next twelve months due to expiring statutes of limitations.

The Company recognizes penalties and interest accrued related to unrecognized tax benefits in income tax expense. As of March 31, 2013, the Company had no material 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 2007.

12. Earnings per Share

The Company has unvested shares of restricted stock and restricted stock units outstanding that are considered participating securities and, therefore, computes basic and diluted earnings per share under the two-class method. Basic earnings per share for the periods are based upon the weighted average number of shares of common stock outstanding during the periods. Diluted earnings per share include the effect of certain stock options.

	Three Months Ended March 31,
	2013			2012
Net income	$	123,347		$	87,813
Less:
Net income attributable to participating securities	(568		)	(610		)
Net income attributable to common shareholders	$	122,779		$	87,203

11

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 March 31,
	2013		2012
Weighted average common shares—basic	66,625,536		66,109,297
Plus incremental shares from:
Assumed exercise of options	283,333		449,220
Weighted average common shares—diluted	66,908,869		66,558,517
Earnings per share:
Basic	$	1.84	$	1.32
Diluted	$	1.84	$	1.31

Excluded from the computation of diluted earnings per share are options to purchase 36,388 and 67,098 shares of common stock for the three months ended March 31, 2013 and 2012, respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive.

13. Pension and Post-Retirement Benefit Costs

Components of net periodic benefit cost are as follows:

	Three Months Ended March 31,
	Pension						Post-retirement Healthcare
	2013			2012			2013		2012
Service cost	$	264		$	254		$	2	$	2
Interest cost	501			647			147		185
Expected return on plan assets	(714		)	(620		)	—		—
Amortization of prior service cost	74			74			21		21
Amortization of net loss	429			439			90		44
Net periodic benefit cost	$	554		$	794		$	260	$	252

The Company contributed $442 to the Salaried pension plan in the first three months of 2012, and contributed $60 and $278 to the Wage pension plan in the first three months of 2013 and 2012, respectively. The Company did not contribute to the Salaried pension plan in the first three months of 2013. The Company expects to make additional contributions of $1,164 to the Salaried pension plan and $870 to the Wage pension plan during the fiscal year ending December 31, 2013.

14. Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2013 were as follows:

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Total
Balances at December 31, 2012	$	(16,351	)	$	5,511		$	(10,840	)
Other comprehensive loss before reclassifications	—			(570		)	(570		)
Amounts reclassified from accumulated other comprehensive loss	378			—			378
Net other comprehensive income (loss) for the period	378			(570		)	(192		)
Balances at March 31, 2013	$	(15,973	)	$	4,941		$	(11,032	)

12

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three months ended March 31, 2013:

Details about Accumulated Other Comprehensive    Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Three Months Ended March 31, 2013
Amortization of pension and other post-retirement items
Prior service costs	(1)	$	(95	)
Net loss	(1)	(519		)
		(614		)
	Provision for income taxes	236
Total reclassifications for the period		$	(378	)

_____________

(1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 8 (Employee Benefits) to the financial statements included in the 2012 Form 10-K.

15. 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, 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.

Contract Disputes with Goodrich and PolyOne. In connection with the 1990 and 1997 acquisitions of the Goodrich Corporation ("Goodrich") chemical manufacturing complex in Calvert City, Kentucky, Goodrich agreed to indemnify the Company for any liabilities related to preexisting contamination at the complex. 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 complex, 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 complex 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 $2,687 in 2012. 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.

Administrative Proceedings. There are several administrative proceedings in Kentucky involving the Company, Goodrich and PolyOne related to the same manufacturing complex 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 complex. 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.

13

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

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 pursuant to an Administrative Settlement Agreement ("AOC"), which became effective on December 9, 2009. See "Change in Regulatory Regime" below. The proceedings have been postponed. Periodic status conferences will be held to evaluate whether additional proceedings will be required.

Change in Regulatory Regime. In May 2009, the Cabinet sent a letter to the U.S. Environmental Protection Agency ("EPA") requesting the EPA's assistance in addressing contamination at the Calvert City site under the U.S. Comprehensive Environmental Response, Compensation, and Liability Act ("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. During the past two years, 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, the AOC and an order to conduct the RIFS. The parties submitted and received EPA approval for a RIFS work plan to implement the AOC. The parties are currently conducting the RIFS.

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 complex 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.

EPA Audit of Ethylene Units in Lake Charles. During 2007, the EPA conducted an audit of the Company's ethylene units in Lake Charles, Louisiana, with a focus on leak detection and repair ("LDAR"). As a result of the audit, the EPA brought allegations that the Company had violated certain environmental laws and regulations pertaining to LDAR. The Company has agreed to settle this matter, subject to court approval, by paying a cash penalty of $500 and has recorded an accrual in such amount.

In addition to the matters described above, the Company is involved in various routine legal proceedings incidental to the conduct of its business. The Company 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

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

16. Segment Information

The Company operates in two principal business segments: Olefins and Vinyls. These segments are strategic business units that offer a variety of different products. The Company manages each segment separately as each business requires different technology and marketing strategies.

	Three Months Ended March 31,
	2013			2012
Net external sales
Olefins
Polyethylene	$	420,768		$	445,420
Styrene, feedstock and other	162,077			286,851
Total Olefins	582,845			732,271
Vinyls
PVC, caustic soda and other	195,246			214,383
Building products	86,556			88,213
Total Vinyls	281,802			302,596
	$	864,647		$	1,034,867
Intersegment sales
Olefins	$	70,283		$	101,457
Vinyls	264			388
	$	70,547		$	101,845
Income (loss) from operations
Olefins	$	161,058		$	129,207
Vinyls	43,663			21,082
Corporate and other	(10,666		)	(4,664		)
	$	194,055		$	145,625
Depreciation and amortization
Olefins	$	23,346		$	23,763
Vinyls	11,884			11,509
Corporate and other	126			122
	$	35,356		$	35,394
Other income (expense), net
Olefins	$	4,010		$	956
Vinyls	(425		)	240
Corporate and other	(66		)	151
	$	3,519		$	1,347
Provision for (benefit from) income taxes
Olefins	$	55,477		$	42,175
Vinyls	13,720			6,016
Corporate and other	(1,251		)	(1,209		)
	$	67,946		$	46,982

15

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

	Three Months Ended March 31,
	2013		2012
Capital expenditures
Olefins	$	50,040	$	17,480
Vinyls	100,317		46,841
Corporate and other	427		581
	$	150,784	$	64,902

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

	Three Months Ended March 31,
	2013			2012
Income from operations	$	194,055		$	145,625
Interest expense	(6,281		)	(12,177		)
Other income, net	3,519			1,347
Income before income taxes	$	191,293		$	134,795

	March 31, 2013		December 31, 2012
Total assets
Olefins	$	1,534,996	$	1,439,308
Vinyls	1,106,500		1,030,912
Corporate and other	917,729		941,976
	$	3,559,225	$	3,412,196

17. Subsequent Events

In March 2013, the Company announced that it had entered into a definitive agreement with CertainTeed Corporation, a subsidiary of the French public company, Compagnie de Saint-Gobain, to purchase its Pipe and Foundation Group business, a leading producer of PVC pipe and fittings for municipal, water well, mining, agriculture and irrigation applications, with an annual production capacity of approximately 150 million pounds, for a cash purchase price of $175,000, including working capital, subject to post-closing adjustments. This transaction closed on May 1, 2013. No pro forma financial information has been provided as the purchase is not significant to the Company's consolidated financial position or results of operations.

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

16

WESTLAKE CHEMICAL CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued

(Unaudited)

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

18. 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"). Each Guarantor Subsidiary is 100% owned by Westlake Chemical Corporation. 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 Guarantor Subsidiaries and the remaining subsidiaries that do not guarantee the 3.60% senior notes due 2022 (the "Non-Guarantor Subsidiaries"), together with consolidating adjustments necessary to present the Company's results on a consolidated basis.

Condensed Consolidating Financial Information as of March 31, 2013

	Westlake Chemical Corporation		Guarantor Subsidiaries		Non- Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	742,898	$	7,648	$	27,341	$	—		$	777,887
Marketable securities	94,903		—		—		—			94,903
Accounts receivable, net	12,629		1,644,221		4,575		(1,253,845		)	407,580
Inventories	—		393,260		14,814		—			408,074
Prepaid expenses and other    current assets	223		12,588		1,725		—			14,536
Deferred income taxes	431		21,581		286		—			22,298
Total current assets	851,084		2,079,298		48,741		(1,253,845		)	1,725,278
Property, plant and equipment, net	—		1,621,290		8,019		—			1,629,309
Equity investments	3,143,697		65,868		32,711		(3,198,362		)	43,914
Other assets, net	16,692		148,886		1,132		(5,986		)	160,724
Total assets	$	4,011,473	$	3,915,342	$	90,603	$	(4,458,193	)	$	3,559,225
Current liabilities
Accounts payable	$	1,252,908	$	221,992	$	15,382	$	(1,258,221	)	$	232,061
Accrued liabilities	15,873		146,546		959		4,376			167,754
Total current liabilities	1,268,781		368,538		16,341		(1,253,845		)	399,815
Long-term debt	752,901		10,889		—		—			763,790
Deferred income taxes	—		361,450		511		(5,986		)	355,975
Other liabilities	—		49,823		31		—			49,854
Stockholders' equity	1,989,791		3,124,642		73,720		(3,198,362		)	1,989,791
Total liabilities and stockholders' equity	$	4,011,473	$	3,915,342	$	90,603	$	(4,458,193	)	$	3,559,225

17

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, 2012

	Westlake Chemical Corporation		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	753,881	$	6,973	$	29,224	$	—		$	790,078
Marketable securities	124,873		—		—		—			124,873
Accounts receivable, net	7,933		1,675,274		2,959		(1,286,007		)	400,159
Inventories	—		385,140		14,158		—			399,298
Prepaid expenses and other    current assets	389		11,386		2,925		—			14,700
Deferred income taxes	431		21,581		293		—			22,305
Total current assets	887,507		2,100,354		49,559		(1,286,007		)	1,751,413
Property, plant and equipment, net	—		1,502,902		7,146		—			1,510,048
Equity investments	3,018,926		65,448		32,923		(3,073,561		)	43,736
Other assets, net	17,033		94,678		1,252		(5,964		)	106,999
Total assets	$	3,923,466	$	3,763,382	$	90,880	$	(4,365,532	)	$	3,412,196
Current liabilities
Accounts payable	$	1,285,530	$	192,443	$	13,969	$	(1,274,892	)	$	217,050
Accrued liabilities	12,808		178,915		852		(11,115		)	181,460
Total current liabilities	1,298,338		371,358		14,821		(1,286,007		)	398,510
Long-term debt	752,872		10,889		—		—			763,761
Deferred income taxes	—		331,320		934		(5,964		)	326,290
Other liabilities	—		51,312		67		—			51,379
Stockholders' equity	1,872,256		2,998,503		75,058		(3,073,561		)	1,872,256
Total liabilities and stockholders' equity	$	3,923,466	$	3,763,382	$	90,880	$	(4,365,532	)	$	3,412,196

18

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 March 31, 2013

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	856,085		$	10,540		$	(1,978	)	$	864,647
Cost of sales	—			629,286			9,530			(1,978		)	636,838
Gross profit	—			226,799			1,010			—			227,809
Selling, general and administrative    expenses	510			31,709			1,535			—			33,754
(Loss) income from operations	(510		)	195,090			(525		)	—			194,055
Interest expense	(6,258		)	(23		)	—			—			(6,281		)
Other income (expense), net	4,309			(290		)	(500		)	—			3,519
(Loss) income before income taxes	(2,459		)	194,777			(1,025		)	—			191,293
(Benefit from) provision for income taxes	(874		)	69,051			(231		)	—			67,946
Equity in net income of subsidiaries	124,932			—			—			(124,932		)	—
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Comprehensive income (loss)	$	123,155		$	126,104		$	(1,364	)	$	(124,740	)	$	123,155

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2012

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	1,026,332		$	9,843		$	(1,308	)	$	1,034,867
Cost of sales	—			854,987			8,551			(1,308		)	862,230
Gross profit	—			171,345			1,292			—			172,637
Selling, general and administrative    expenses	505			24,756			1,751			—			27,012
(Loss) income from operations	(505		)	146,589			(459		)	—			145,625
Interest expense	(12,171		)	(6		)	—			—			(12,177		)
Other income (expense), net	3,534			(1,700		)	(487		)	—			1,347
(Loss) income before income taxes	(9,142		)	144,883			(946		)	—			134,795
(Benefit from) provision for income taxes	(3,173		)	50,231			(76		)	—			46,982
Equity in net income of subsidiaries	93,782			—			—			(93,782		)	—
Net income (loss)	$	87,813		$	94,652		$	(870	)	$	(93,782	)	$	87,813
Comprehensive income (loss)	$	105,019		$	111,344		$	(358	)	$	(110,986	)	$	105,019

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 for the Three Months Ended March 31, 2013

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Adjustments to reconcile net income    (loss) to net cash (used for) provided    by operating activities
Depreciation and amortization	365			34,766			590			—			35,721
Deferred income taxes	(23		)	29,896			(407		)	—			29,466
Net changes in working capital    and other	(129,403		)	(68,474		)	663			124,932			(72,282		)
Net cash (used for) provided by    operating activities	(5,714		)	121,914			52			—			116,252
Cash flows from investing activities
Additions to property, plant and    equipment	—			(149,113		)	(1,671		)	—			(150,784		)
Proceeds from disposition of assets	—			—			2			—			2
Proceeds from repayment of loan    to affiliate	—			—			167			—			167
Proceeds from sales and maturities of    securities	124,873			—			—			—			124,873
Purchase of securities	(94,903		)	—			—			—			(94,903		)
Settlements of derivative instruments	—			(679		)	—			—			(679		)
Net cash provided by (used for)    investing activities	29,970			(149,792		)	(1,502		)	—			(121,324		)
Cash flows from financing activities
Intercompany financing	(28,120		)	28,553			(433		)	—			—
Dividends paid	(12,553		)	—			—			—			(12,553		)
Proceeds from exercise of stock options	1,590			—			—			—			1,590
Windfall tax benefits from share-based    payment arrangements	3,844			—			—			—			3,844
Net cash (used for) provided by    financing activities	(35,239		)	28,553			(433		)	—			(7,119		)
Net (decrease) increase in cash and    cash equivalents	(10,983		)	675			(1,883		)	—			(12,191		)
Cash and cash equivalents at beginning    of period	753,881			6,973			29,224			—			790,078
Cash and cash equivalents at end of period	$	742,898		$	7,648		$	27,341		$	—		$	777,887

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 for the Three Months Ended March 31, 2012

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	87,813		$	94,652		$	(870	)	$	(93,782	)	$	87,813
Adjustments to reconcile net income    (loss) to net cash (used for) provided    by operating activities
Depreciation and amortization	400			34,593			801			—			35,794
Deferred income taxes	(48		)	779			60			—			791
Net changes in working capital    and other	(98,271		)	(12,415		)	(1,918		)	93,782			(18,822		)
Net cash (used for) provided by    operating activities	(10,106		)	117,609			(1,927		)	—			105,576
Cash flows from investing activities
Additions to property, plant and    equipment	—			(64,871		)	(31		)	—			(64,902		)
Proceeds from disposition of assets	—			—			3			—			3
Proceeds from repayment of loan    to affiliate	—			—			167			—			167
Purchase of securities	—			(2,961		)	—			—			(2,961		)
Settlements of derivative instruments	—			511			—			—			511
Net cash (used for) provided by    investing activities	—			(67,321		)	139			—			(67,182		)
Cash flows from financing activities
Intercompany financing	44,883			(49,242		)	4,359			—			—
Dividends paid	(4,914		)	—			—			—			(4,914		)
Proceeds from exercise of stock options	480			—			—			—			480
Utilization of restricted cash	30,800			—			—			—			30,800
Windfall tax benefits from share-based    payment arrangements	4,481			—			—			—			4,481
Net cash provided by (used for)    financing activities	75,730			(49,242		)	4,359			—			30,847
Net increase in cash and cash equivalents	65,624			1,046			2,571			—			69,241
Cash and cash equivalents at beginning    of period	803,320			2,517			20,064			—			825,901
Cash and cash equivalents at end of period	$	868,944		$	3,563		$	22,635		$	—		$	895,142

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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, 2012 (the "2012 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 manufacturer and marketer of petrochemicals, polymers and fabricated building products. Our two principal business segments are Olefins and Vinyls. We use the majority of our internally-produced basic chemicals to produce higher value-added chemicals and building products.

Since 2009 and continuing through the first quarter of 2013, a cost advantage for natural gas liquids-based ethylene producers over naphtha-based ethylene producers has allowed a strong export market for ethylene derivatives and higher margins for North American chemical producers, including Westlake. Increased global demand for polyethylene in recent years in particular has resulted in improved operating margins and cash flow for our Olefins segment. However, some olefins industry consultants predict that a significant increase in worldwide ethylene and ethylene derivative capacity may occur within the next decade, with the largest increases in Asia and North America. As a result, our Olefins segment operating margins may be negatively impacted.

Continued weakness in the U.S. construction markets and budgetary constraints in municipal spending have contributed to lower domestic demand for our vinyls products. In addition, increases in feedstock costs, combined with the industry's inability to sufficiently raise domestic prices for PVC resin and building products in order to offset cost increases, affected our Vinyls segment's operating results in 2010 and 2011. However, since late 2010, the PVC industry 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, domestic PVC resin industry operating rates have improved since 2010, largely due to higher PVC resin export shipments. However, looking forward, our Vinyls segment operating rates and margins may continue to be negatively impacted by the slow recovery of U.S. construction markets.

The current U.S. economic environment, while slowly improving, continues to be somewhat challenging for our customers. However, we believe our customer base is generally healthy. As we continue to manage our business in this environment, including the slowdown in construction activity, we have taken steps designed to address the changes in demand and margins in our Vinyls segment and its resulting impact on our operations by matching production with sales demand and continuing to operate our plants in an efficient manner. We continue to monitor our cost management programs and discretionary capital spending. The impact of the weak global economic environment has been challenging to our business and, depending on the performance of the global economy in the remainder of 2013 and beyond, could have a negative effect on our financial condition, results of operations or cash flows.

Recent Developments

In March 2013, we announced that we had entered into a definitive agreement with CertainTeed Corporation, a subsidiary of the French public company, Compagnie de Saint-Gobain, to purchase its Pipe and Foundation Group business, a leading producer of PVC pipe and fittings for municipal, water well, mining, agriculture and irrigation applications, with an annual production capacity of approximately 150 million pounds, for a cash purchase price of $175.0 million, including working capital, subject to post-closing adjustments. This transaction closed on May 1, 2013.

In March 2013, we completed planned major maintenance activities, or turnaround, of one of the ethylene units at our Lake Charles, Louisiana complex. In conjunction with this turnaround, we completed the previously announced expansion to increase the ethane-based ethylene capacity of that ethylene unit. The unit was restarted after 74 days. Income from operations for the first quarter of 2013 was negatively impacted as a result of the lost production, unabsorbed fixed manufacturing costs and other costs related to the turnaround and expansion.

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Results of Operations

	Three Months Ended March 31,
	2013			2012
	(dollars in thousands, except per share data)
Net external sales
Olefins
Polyethylene	$	420,768		$	445,420
Styrene, feedstock and other	162,077			286,851
Total Olefins	582,845			732,271
Vinyls
PVC, caustic soda and other	195,246			214,383
Building products	86,556			88,213
Total Vinyls	281,802			302,596
Total	$	864,647		$	1,034,867
Income (loss) from operations
Olefins	$	161,058		$	129,207
Vinyls	43,663			21,082
Corporate and other	(10,666		)	(4,664		)
Total income from operations	194,055			145,625
Interest expense	(6,281		)	(12,177		)
Other income, net	3,519			1,347
Provision for income taxes	67,946			46,982
Net income	$	123,347		$	87,813
Diluted earnings per share	$	1.84		$	1.31
	Three Months Ended March 31, 2013
	Average Sales Price			Volume
Product sales price and volume percentage change from prior year period
Olefins	-2.3		%	-18.1		%
Vinyls	-0.2		%	-6.7		%
Company average	-1.7		%	-14.7		%
	Three Months Ended March 31,
	2013			2012
Average industry prices (1)
Ethane (cents/lb)	8.7			18.9
Propane (cents/lb)	20.5			29.8
Ethylene (cents/lb) (2)	63.3			62.3
Polyethylene (cents/lb) (3)	97.3			99.0
Styrene (cents/lb) (4)	85.9			74.3
Caustic soda ($/short ton) (5)	602.5			570.8
Chlorine ($/short ton) (6)	255.0			274.2
PVC (cents/lb) (7)	59.2			56.5

_____________

(1) Industry pricing data was obtained through 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.

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(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 March 31, 2013, net income was $123.3 million, or $1.84 per diluted share, on net sales of $864.6 million. This represents an increase in net income of $35.5 million, or $0.53 per diluted share, compared to the quarter ended March 31, 2012 net income of $87.8 million, or $1.31 per diluted share, on net sales of $1,034.9 million. Net sales for the first quarter of 2013 decreased by $170.3 million compared to net sales for the first quarter of 2012, mainly attributable to lower feedstock, ethylene and ethylene co-product sales volumes and lower sales prices for polyethylene and PVC resin. Ethylene and ethylene co-product sales volumes were lower primarily due to the turnaround and expansion of one of our Lake Charles ethylene units, which lasted 74 days. Income from operations was $194.1 million for the first quarter of 2013 as compared to $145.6 million for the first quarter of 2012. Income from operations for the first quarter of 2013 benefited primarily from improved olefins and vinyls integrated product margins predominantly due to lower feedstock and energy costs as compared to the prior year period. Industry ethane prices declined 54.0% and industry propane prices declined 31.2% in the first quarter of 2013 as compared to the first quarter of 2012.

RESULTS OF OPERATIONS

First Quarter 2013 Compared with First Quarter 2012

Net Sales. Net sales decreased by $170.3 million, or 16.5%, to $864.6 million in the first quarter of 2013 from $1,034.9 million in the first quarter of 2012, primarily attributable to lower sales volumes for feedstock, ethylene and ethylene co-products and lower sales prices for polyethylene and PVC resin. Average sales prices for the first quarter of 2013 decreased by 1.7% as compared to the first quarter of 2012. Overall sales volume decreased by 14.7% as compared to the first quarter of 2012.

Gross Profit. Gross profit margin percentage increased to 26.3% for the first quarter of 2013 from 16.7% for the first quarter of 2012, driven mainly by improved olefins and vinyls integrated product margins mainly attributable to lower feedstock and energy costs. Our raw material cost in both segments normally tracks industry prices, which experienced a decrease of 54.0% and 31.2% for ethane and propane, respectively, as compared to the first quarter of 2012. Sales prices decreased an average of 1.7% for the first quarter of 2013 as compared to the first quarter of 2012.

Selling, General and Administrative Expenses. Selling, general and administrative expenses for the first quarter of 2013 of $33.8 million increased by $6.8 million as compared to the first quarter of 2012 mainly due to an increase in payroll and related labor costs, including incentive compensation, and consulting fees.

Interest Expense. Interest expense decreased by $5.9 million to $6.3 million in the first quarter of 2013 from $12.2 million in the first quarter of 2012 largely as a result of increased capitalized interest on major capital projects and lower average interest rates in the first quarter of 2013 as compared to the prior year period. Debt balances remained relatively unchanged from the prior year period.

Other Income, Net. Other income, net increased to $3.5 million in the first quarter of 2013 from $1.3 million in the first quarter of 2012, mainly due to higher equity in income from our joint ventures and the settlement of a claim against a supplier in the first quarter of 2013.

Income Taxes. The effective income tax rate was 35.5% for the first quarter of 2013. The effective income tax rate for the first quarter of 2013 was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction. The effective income tax rate was 34.9% for the first quarter of 2012. The effective income tax rate for the first quarter of 2012 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.

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Olefins Segment

Net Sales. Net sales decreased by $149.5 million, or 20.4%, to $582.8 million in the first quarter of 2013 from $732.3 million in the first quarter of 2012, predominantly due to lower feedstock, ethylene and ethylene co-product sales volumes and lower polyethylene sales prices as compared to the prior year period. Ethylene and ethylene co-product sales volumes were lower primarily due to the turnaround and expansion of the Lake Charles ethylene unit. Average sales prices for the Olefins segment decreased by 2.3% in the first quarter of 2013 as compared to the first quarter of 2012. Average sales volumes decreased by 18.1% in the first quarter of 2013 as compared to the first quarter of 2012.

Income from Operations. Income from operations increased by $31.9 million, or 24.7%, to $161.1 million in the first quarter of 2013 from $129.2 million in the first quarter of 2012. This increase was mainly attributable to higher olefins integrated product margins as compared to the prior year period. Margins improved primarily as a result of significantly lower feedstock and energy costs, which were only partially offset by lower sales prices. Income from operations in the first quarter of 2013 was negatively impacted as a result of the lost production and the expensing of $19.9 million related to unabsorbed fixed manufacturing costs and other costs associated with the turnaround and expansion of the Lake Charles ethylene unit. Trading activity in the first quarter of 2013 resulted in a gain of $7.3 million as compared to a gain of $0.6 million in the first quarter of 2012.

Vinyls Segment

Net Sales. Net sales decreased by $20.8 million, or 6.9%, to $281.8 million in the first quarter of 2013 from $302.6 million in the first quarter of 2012. This decrease was mainly attributable to lower sales volumes for all major products, partially offset by higher sales prices for caustic and building products. Average sales prices for the Vinyls segment decreased marginally by 0.2% in the first quarter of 2013 as compared to the first quarter of 2012. Average sales volumes for the Vinyls segment decreased by 6.7% in the first quarter of 2013 as compared to the first quarter of 2012.

Income from Operations. Income from operations increased by $22.6 million, or 107.1%, to $43.7 million in the first quarter of 2013 from $21.1 million in the first quarter of 2012. This increase was primarily driven by higher vinyls integrated product margins largely resulting from lower feedstock costs as compared to the prior year period. While Vinyls segment operating results for the first quarter of 2013 generally improved as compared to recent quarters, our Vinyls segment remains constrained by weakness in the U.S. construction markets and budgetary constraints in municipal spending.

CASH FLOW DISCUSSION FOR THE THREE MONTHS ENDED MARCH 31, 2013 AND 2012

Cash Flows

Operating Activities

Operating activities provided cash of $116.3 million in the first three months of 2013 compared to cash provided of $105.6 million in the first three months of 2012. The $10.7 million increase in cash flows from operating activities was mainly due to an increase in income from operations and a decrease in working capital as compared to the prior year period, partially offset by deferred turnaround costs from the turnaround of our Lake Charles ethylene unit. Income from operations increased by $48.5 million in the first three months of 2013 primarily as a result of higher olefins and vinyls integrated product margins 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 $18.8 million in the first three months of 2013, compared to $20.6 million of cash used in the first three months of 2012, a favorable change of $1.8 million. An increase in current liabilities and a decrease in accounts receivable largely attributable to lower average sales volumes were mostly offset by an increase in inventory during the 2013 period. In addition, inventory decreased during the 2012 period as high cost feedstock in inventory at December 31, 2011 flowed through cost of sales in the first quarter of 2012.

Investing Activities

Net cash used for investing activities during the first three months of 2013 was $121.3 million as compared to net cash used for investing activities of $67.2 million in the first three months of 2012. Capital expenditures were $150.8 million in the first three months of 2013 compared to $64.9 million in the first three months of 2012. The higher capital expenditures in the first three months of 2013 were largely attributable to the construction of the new chlor-alkali plant at our Geismar, Louisiana facility, the expansion of the ethylene unit at our Lake Charles complex and the feedstock conversion and ethylene furnaces modernization projects at our Calvert City, Kentucky complex. Capital expenditures in the first three months of 2012 were mainly incurred on the construction of the new Geismar chlor-alkali plant and the expansion of the ethylene unit at our Lake Charles complex. The remaining capital expenditures in the first three months of 2013 and 2012 primarily related to projects to improve production capacity or reduce costs and maintenance, safety and environmental projects at our various facilities.

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Purchases of securities in the first three months of 2013 totaled $94.9 million and were comprised of short-term commercial paper. We also received aggregate proceeds of $124.9 million from the maturities of short-term commercial paper in the first three months of 2013. The activity during the first three months of 2012 was primarily related to the purchase of equity securities.

Financing Activities

Net cash used for financing activities during the first three months of 2013 was $7.1 million as compared to net cash provided of $30.8 million in the first three months of 2012. The activity during the first three months of 2013 was primarily related to the $12.6 million payment of cash dividends, partially offset by proceeds of $1.6 million from the exercise of stock options. The activity during the first three months of 2012 was mainly related to the draw-down of our restricted cash and proceeds from the exercise of stock options, partially offset by the $4.9 million payment of cash dividends.

LIQUIDITY AND CAPITAL RESOURCES

Liquidity and Financing Arrangements

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

In October 2012, we announced a project to convert the feedstock for our Calvert City ethylene plant from propane to ethane and the planned increase in ethylene capacity from 450 million pounds annually to 630 million pounds annually. The ethylene expansion and feedstock conversion project is targeted for start-up in the second quarter of 2014. In addition, we announced an expansion of the existing PVC plant in Calvert City, which should allow us to take advantage of the increased ethylene production at our Calvert City complex and to provide additional PVC resin to meet the growing demands of our global customers. The expansion of the Calvert City PVC plant is expected to increase PVC resin capacity by approximately 200 million pounds annually and is targeted for completion by late 2014. These projects are currently estimated to cost in the range of $210.0 million to $240.0 million in the aggregate. Further, in December 2011, we announced plans to perform a major modernization of the ethylene furnaces at our Calvert City complex. We currently expect the modernization to be completed by mid-2013. This capital project is currently estimated to cost approximately $40.0 million.

In August 2010, we announced that we intend to proceed with the previously announced plans for the construction of a new chlor-alkali plant at our Geismar facility. The project is currently estimated to cost in the range of $390.0 million to $420.0 million and is targeted for start-up in the fourth quarter of 2013.

These capital projects are expected to be funded with cash on hand, cash flow from operations, and, if necessary, borrowings under our revolving credit facility and other external financing. As of March 31, 2013, we had incurred a total cost of approximately $344.7 million on these capital projects.

In April 2011, we announced an expansion program to increase the ethane-based ethylene capacity of both of the ethylene units at our Lake Charles complex. We completed the expansion of the first ethylene unit in the first quarter of 2013. We are evaluating plans for the expansion of the second ethylene unit at our Lake Charles complex.

In August 2011, our Board of Directors authorized a stock repurchase program totaling $100.0 million. As of March 31, 2013, we had repurchased 284,493 shares of our common stock for an aggregate purchase price of approximately $13.3 million under this program. We did not repurchase any shares under this program during the three months ended March 31, 2013. Purchases under this 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 program will be influenced by our cash on hand, our cash flow from operations, general market conditions and other factors. The 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 may 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, Cash Equivalents and Current Marketable Securities

As of March 31, 2013, our cash, cash equivalents and current marketable securities totaled $872.8 million. In addition, we have a revolving credit facility available to supplement cash if needed, as described under "Debt" below.

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Debt

As of March 31, 2013, our long-term debt, including current maturities, totaled $763.8 million, consisting of $250.0 million principal amount of 3.60% senior notes due 2022 (less the unamortized discount of $1.1 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 March 31, 2013, debt outstanding under the tax-exempt waste disposal revenue bonds bore interest at a variable rate. As of March 31, 2013, 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.

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 $150.0 million) under certain circumstances if certain lenders agree to commit to such an increase.

At March 31, 2013, 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 1.75% to 2.25% or a base rate plus a spread ranging from 0.25% to 0.75%. The revolving credit facility also requires an unused commitment fee of 0.375% 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 September 16, 2016. As of March 31, 2013, we had outstanding letters of credit totaling $16.2 million and borrowing availability of $383.8 million under the revolving credit facility.

Our revolving credit facility requires us to maintain a minimum fixed charge coverage ratio of 1.0:1 for successive 30-day periods after any date on which the borrowing availability under the facility is less than the greater of (1) 12.5% of the commitments under the facility and (2) $50.0 million, until the borrowing availability exceeds the greater of the amount in clause (1) and the amount in clause (2) for a 30-day period.

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 $100.0 million or 25% 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 $70.0 million or 17.5% 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. However, we may make specified distributions up to an aggregate of $25.0 million and specified acquisitions up to an aggregate of $25.0 million if either we maintain a minimum borrowing availability of at least the greater of $70.0 million or 17.5% of the total bank commitments under our revolving credit facility or we meet the minimum fixed charge coverage ratio of 1.0:1 under our revolving credit facility. Notwithstanding the foregoing, we may make (1) investments up to $200.0 million in one or more joint ventures that own feedstock, raw material and ethylene pipeline, storage and fractionating facilities and (2) additional investments up to $55.0 million in Suzhou Huasu Plastics Co., Ltd. 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 2012 Form 10-K for more information on the revolving credit facility.

GO Zone and IKE Zone Bonds

As of March 31, 2013, 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 2012 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,

27

provide limitations on incurrence of additional indebtedness, the payment of dividends, certain investments and acquisitions and sales of assets. However, the effectiveness of certain of these restrictions is currently suspended because the Senior Notes are currently rated investment grade by at least two nationally recognized credit rating agencies. The most significant of these provisions, if it were currently effective, would restrict us from incurring additional debt, except specified permitted debt (including borrowings under our credit facility), when our fixed charge coverage ratio is below 2.0:1. These limitations are subject to a number of important qualifications and exceptions, including, without limitation, an exception for the payment of our regular quarterly dividend of up to $0.20 per share (currently $0.1875 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 2012 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.

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, 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.

Off-Balance Sheet Arrangements

None.

FORWARD-LOOKING STATEMENTS

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

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

• industry market outlook;

• production capacities;

28

• 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 the expansion and feedstock conversion programs at our Lake Charles and Calvert City complexes;

• timing, funding and results of the planned new chlor-alkali plant in Geismar;

• health of our customer base;

• pension plan 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;

• the utilization of net operating loss carryforwards;

• 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 2012 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 and worldwide economies, including those due to political tensions in the Middle East and elsewhere;

• current and potential governmental regulatory actions in the United States 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 implement our business strategies; and

• creditworthiness of our customers.

Many of these factors are beyond our ability to control or predict. Any of the factors, or a combination of these factors, could materially affect our future results of operations and the ultimate accuracy of the forward-looking statements. These forward-looking statements are not guarantees of our future performance, and our actual results and future developments may differ materially from those projected in the forward-looking statements. Management cautions against putting undue reliance

29

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 March 31, 2013, a hypothetical $0.10 increase in the price of a gallon of ethane would have increased our income before taxes by $5.4 million and a hypothetical $0.10 increase in the price of a pound of ethylene would have decreased our income before taxes by $10.8 million. Additional information concerning derivative commodity instruments appears in Notes 9 and 10 to the consolidated financial statements.

Interest Rate Risk

We are exposed to interest rate risk with respect to fixed and variable rate debt. At March 31, 2013, we had variable rate debt of $10.9 million outstanding. All of the debt outstanding under our revolving credit facility (none was outstanding at March 31, 2013) 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 March 31, 2013 was 0.22%. 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 March 31, 2013, 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.

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 March 31, 2013 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

30

PART II. OTHER INFORMATION

Item 1. Legal Proceedings

The 2012 Form 10-K, filed on February 22, 2013, contained a description of various legal proceedings in which we are involved, including environmental proceedings at our facilities in Calvert City. See Note 15 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 2012 Form 10-K. There have been no material changes from those risk factors, except as described below.

We may have difficulties integrating the operations of the business we acquired from CertainTeed.

If we are unable to integrate or to successfully manage the Pipe and Foundation Group business we acquired from CertainTeed Corporation, our business, financial condition, results of operations and cash flows could be adversely affected. We may not be able to realize the operating efficiencies, synergies, cost savings or other benefits expected from the acquisition for a number of reasons, including, but not limited to, the following:

• we may fail to integrate the business into a cohesive, efficient enterprise;

• our resources, including management resources, are limited and may be strained, and the acquisition may divert our management's attention from initiating or carrying out programs to save costs or enhance revenues; and

• our failure to retain key employees and contracts of the business.

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 March 31, 2013:

Period	Total Number of Shares Purchased (1)	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)
January 2013	—	$	—	—	$	86,698,000
February 2013	45,743	$	84.10	—	$	86,698,000
March 2013	—	$	—	—	$	86,698,000
	45,743	$	84.10	—

_____________

(1) Represents shares withheld in satisfaction of withholding taxes due upon the vesting of restricted stock granted to our employees under the 2004 Plan.

(2) On August 22, 2011, we announced the authorization by our Board of Directors of a $100.0 million stock repurchase program. As of March 31, 2013, 284,493 shares of common stock had been acquired at an aggregate purchase price of $13.3 million. Decisions regarding the amount and the timing of purchases under the program will be influenced by our cash on hand, our cash flow from operations, general market conditions and other factors. The program may be discontinued by our Board of Directors at any time.

31

Item 6. Exhibits

Exhibit No.
10.1	Form of Restricted Stock Units Award Letter effective as of February 15, 2013 (incorporated by reference to Westlake's Annual Report on Form 10-K for the year ended December 31, 2012, filed on February 22, 2013, File No. 1-32260)
10.2	Consultant's Agreement dated March 26, 2013 by and between Westlake Management Services Inc. and Donald M. Condon, Jr. (incorporated by reference to Westlake's Current Report on Form 8-K, filed on March 29, 2013, 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)
101.INS	XBRL Instance Document (1)
101.SCH	XBRL Taxonomy Extension Schema Document (1)
101.CAL	XBRL Taxonomy Extension Calculation Linkbase Document (1)
101.DEF	XBRL Taxonomy Extension Definition Linkbase Document (1)
101.LAB	XBRL Taxonomy Extension Label Linkbase Document (1)
101.PRE	XBRL Taxonomy Extension Presentation Linkbase Document (1)

_____________

(1) Pursuant to Rule 406T of Regulation S-T, this interactive data file is deemed not filed or part of a registration statement or prospectus for purposes of sections 11 or 12 of the Securities Act of 1933, is deemed not filed for purposes of section 18 of the Securities Exchange Act of 1934, and otherwise is not subject to liability under these sections.

32

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:	May 7, 2013	By:	/S/    ALBERT CHAO
			Albert Chao
			President and Chief Executive Officer (Principal Executive Officer)
Date:	May 7, 2013	By:	/S/    M. STEVEN BENDER
			M. Steven Bender
			Senior Vice President, Chief Financial Officer and Treasurer (Principal Financial Officer)

33

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 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:	May 7, 2013	/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 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:	May 7, 2013	/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 March 31, 2013 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:	May 7, 2013	/S/    ALBERT CHAO
		Albert Chao
		President and Chief Executive Officer (Principal Executive Officer)
Date:	May 7, 2013	/S/    M. STEVEN BENDER
		M. Steven Bender
		Senior Vice President, Chief Financial Officer and Treasurer (Principal Financial Officer)

XML

Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Finished products	$ 198,639	$ 200,940
Feedstock, additives and chemicals	154,304	143,912
Materials and supplies	55,131	54,446
Inventories	$ 408,074	$ 399,298

XML

Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 123,347	$ 87,813
Less: Net income attributable to participating securities	(568)	(610)
Net income attributable to common shareholders	$ 122,779	$ 87,203

XML

Derivative Instruments (Derivative Assets Reported on Balance Sheet and Subject to Enforceable Master Netting Arrangements) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Offsetting Assets [Line Items]
Derivative assets not subject to enforceable master netting arrangements	$ 9,057	$ 13,032
Total derivative assets	0	0
Total derivative assets	9,057	13,032
Subject to Master Netting | Commodity Forward Contracts
Offsetting Assets [Line Items]
Total derivative assets	0	0
Gross Amounts of Recognized Assets	1,145	1,395
Gross Amounts Offset in the Consolidated Balance Sheet	$ (1,145)	$ (1,395)

XML

Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Basic	66,625,536	66,109,297
Plus incremental shares from: Assumed exercise of options	283,333	449,220
Weighted average common shares-diluted	66,908,869	66,558,517
Earnings per share: Basic	$ 1.84	$ 1.32
Earnings per share: Diluted	$ 1.84	$ 1.31

XML

Derivative Instruments (Fair Values of Derivative Instruments in Consolidated Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accrued Liabilities
Derivatives, Fair Value [Line Items]
Total derivative liabilities	$ 9,843	$ 13,694
Accounts Receivable
Derivatives, Fair Value [Line Items]
Total derivative assets	10,202	14,427
Commodity Forward Contracts | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Designated as hedging instruments, Derivative Liabilities	0	399
Not designated as hedging instruments, Derivative Liabilities	9,843	13,295
Commodity Forward Contracts | Accounts Receivable
Derivatives, Fair Value [Line Items]
Designated as hedging instruments, Derivative Assets	8,299	13,032
Not designated as hedging instruments, Derivative Assets	$ 1,903	$ 1,395

XML

Accumulated Other Comprehensive Income (Tables)

3 Months Ended

Mar. 31, 2013

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

Changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2013 were as follows:

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Total
Balances at December 31, 2012	$	(16,351	)	$	5,511		$	(10,840	)
Other comprehensive loss before reclassifications	—			(570		)	(570		)
Amounts reclassified from accumulated other comprehensive loss	378			—			378
Net other comprehensive income (loss) for the period	378			(570		)	(192		)
Balances at March 31, 2013	$	(15,973	)	$	4,941		$	(11,032	)

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three months ended March 31, 2013:

Details about Accumulated Other Comprehensive    Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Three Months Ended March 31, 2013
Amortization of pension and other post-retirement items
Prior service costs	(1)	$	(95	)
Net loss	(1)	(519		)
		(614		)
	Provision for income taxes	236
Total reclassifications for the period		$	(378	)

_____________

(1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 8 (Employee Benefits) to the financial statements included in the 2012 Form 10-K.

XML

Pension and Post-Retirement Benefit Costs (Additional Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Document Fiscal Year Focus	2013
Salaried Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 0	$ 442
Expected additional contributions	1,164
Wage Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	60	278
Expected additional contributions	$ 870

XML

Basis of Financial Statements (Policies)

3 Months Ended

Mar. 31, 2013

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 have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2012 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, 2012 (the "2012 Form 10-K"), filed with the SEC on February 22, 2013. 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, 2012.

In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of March 31, 2013, its results of operations for the three months ended March 31, 2013 and 2012 and the changes in its cash position for the three months ended March 31, 2013 and 2012.

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, 2013 or any other interim period. The preparation of financial statements in conformity with generally accepted accounting principles in the United States 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

Disclosures about Offsetting Assets and Liabilities

In December 2011, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on disclosures for offsetting assets and liabilities. The new accounting guidance requires companies to disclose both gross and net information about (1) instruments and transactions eligible for offset in the statement of financial position, and (2) instruments and transactions subject to an agreement similar to a master netting arrangement. The FASB issued another accounting standards update clarifying the scope of the assets and liabilities offset disclosure requirements in January 2013. The effective date of the disclosure requirements remains unchanged. The Company adopted the new guidance as of January 1, 2013, and the adoption did not have an impact on the Company's consolidated financial position, results of operations or cash flows.

Testing Indefinite-Lived Intangible Assets for Impairment

In July 2012, the FASB issued an accounting standards update to simplify how entities test indefinite-lived intangible assets for impairment and to improve consistency in impairment testing guidance among long-lived asset categories. The new accounting guidance provides an entity with an option to first assess qualitative factors to determine whether it is more likely than not that an indefinite-lived intangible asset is impaired as a basis for determining whether it is necessary to perform the quantitative impairment test under current accounting guidance. If an entity concludes that it is not more likely than not that the indefinite-lived intangible asset is impaired, then the entity is not required to take further action. However, if an entity concludes otherwise, then it is required to determine the fair value of the indefinite-lived intangible asset and perform the quantitative impairment test by comparing the fair value with the carrying amount in accordance with current accounting guidance. Also under this new accounting guidance, an entity has the option to bypass the qualitative assessment for any indefinite-lived intangible asset in any period and proceed directly to performing the quantitative impairment test, but may resume performing the qualitative assessment in any subsequent period. The Company adopted the new indefinite-lived intangible assets test guidance as of January 1, 2013, and the adoption did not have a material impact on the Company's consolidated financial position, results of operations or cash flows.

Reclassifications Out of Accumulated Other Comprehensive Income

In February 2013, the FASB issued an accounting standards update on reporting items reclassified out of accumulated other comprehensive income. The new accounting guidance requires companies to present either parenthetically on the face of the financial statements or in the notes, significant amounts reclassified from each component of accumulated other comprehensive income and the income statement line items affected by the reclassification, with certain exceptions. The Company adopted the new guidance as of January 1, 2013, and the adoption did not have an impact on the Company's consolidated financial position, results of operations or cash flows.

XML

Fair Value Measurements (Summary of Assets and Liabilities Accounted at Fair Value on Recurring Basis) (Details) (Recurring, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Hedged portion of firm commitment assets		$ 399
Hedged portion of firm commitment liabilities	(8,299)	(13,032)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Hedged portion of firm commitment assets		0
Hedged portion of firm commitment liabilities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Hedged portion of firm commitment assets		399
Hedged portion of firm commitment liabilities	(8,299)	(13,032)
Commodity Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total derivative assets	10,202	14,427
Gross Amounts of Recognized Liabilities	(9,843)	(13,694)
Commodity Forward Contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total derivative assets	1,145	1,395
Gross Amounts of Recognized Liabilities	0	0
Commodity Forward Contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total derivative assets	9,057	13,032
Gross Amounts of Recognized Liabilities	$ (9,843)	$ (13,694)

XML

Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term debt	$ 763,790	$ 763,761
3.60% Senior Notes Due 2022
Debt Instrument [Line Items]
Maturity	2022
Stated interest rate	3.60%
Senior notes	248,901	248,872
6 1/2% Senior Notes Due 2029
Debt Instrument [Line Items]
Maturity	2029
Stated interest rate	6.50%
Senior notes	100,000	100,000
6 3/4% Senior Notes Due 2032
Debt Instrument [Line Items]
Maturity	2032
Stated interest rate	6.75%
Senior notes	250,000	250,000
2035 GO Zone 6 1/2% Notes
Debt Instrument [Line Items]
Maturity	2035
Stated interest rate	6.50%
Senior notes	89,000	89,000
2035 IKE Zone 6 1/2% Notes
Debt Instrument [Line Items]
Maturity	2035
Stated interest rate	6.50%
Senior notes	65,000	65,000
Loan Related To Tax-Exempt Waste Disposal Revenue Bonds Due 2027
Debt Instrument [Line Items]
Maturity	2027
Non-current loan payable	$ 10,889	$ 10,889

XML

Current Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Schedule of Held-to-maturity Securities [Line Items]
Marketable securities	$ 94,903	$ 124,873
Short-term corporate debt securities
Schedule of Held-to-maturity Securities [Line Items]
Marketable securities	$ 94,903	$ 124,873

XML

Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Tax Disclosure [Abstract]
Effective income tax rate	35.50%	34.90%
U.S. federal statutory income tax rate	35.00%	35.00%
Anticpated reductions to unrecognized tax benefits within next twelve months	$ 621

XML

Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 777,887	$ 790,078	$ 895,142	$ 825,901
Marketable securities	94,903	124,873
Accounts receivable, net	407,580	400,159
Inventories	408,074	399,298
Prepaid expenses and other current assets	14,536	14,700
Deferred income taxes	22,298	22,305
Total current assets	1,725,278	1,751,413
Property, plant and equipment, net	1,629,309	1,510,048
Equity investments	43,914	43,736
Other assets, net	160,724	106,999
Total assets	3,559,225	3,412,196
Accounts payable	232,061	217,050
Accrued liabilities	167,754	181,460
Total current liabilities	399,815	398,510
Long-term debt	763,790	763,761
Deferred income taxes	355,975	326,290
Other liabilities	49,854	51,379
Stockholders' equity	1,989,791	1,872,256
Total liabilities and stockholders' equity	3,559,225	3,412,196
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	742,898	753,881	868,944	803,320
Marketable securities	94,903	124,873
Accounts receivable, net	12,629	7,933
Inventories	0	0
Prepaid expenses and other current assets	223	389
Deferred income taxes	431	431
Total current assets	851,084	887,507
Property, plant and equipment, net	0	0
Equity investments	3,143,697	3,018,926
Other assets, net	16,692	17,033
Total assets	4,011,473	3,923,466
Accounts payable	1,252,908	1,285,530
Accrued liabilities	15,873	12,808
Total current liabilities	1,268,781	1,298,338
Long-term debt	752,901	752,872
Deferred income taxes	0	0
Other liabilities	0	0
Stockholders' equity	1,989,791	1,872,256
Total liabilities and stockholders' equity	4,011,473	3,923,466
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	7,648	6,973	3,563	2,517
Marketable securities	0	0
Accounts receivable, net	1,644,221	1,675,274
Inventories	393,260	385,140
Prepaid expenses and other current assets	12,588	11,386
Deferred income taxes	21,581	21,581
Total current assets	2,079,298	2,100,354
Property, plant and equipment, net	1,621,290	1,502,902
Equity investments	65,868	65,448
Other assets, net	148,886	94,678
Total assets	3,915,342	3,763,382
Accounts payable	221,992	192,443
Accrued liabilities	146,546	178,915
Total current liabilities	368,538	371,358
Long-term debt	10,889	10,889
Deferred income taxes	361,450	331,320
Other liabilities	49,823	51,312
Stockholders' equity	3,124,642	2,998,503
Total liabilities and stockholders' equity	3,915,342	3,763,382
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	27,341	29,224	22,635	20,064
Marketable securities	0	0
Accounts receivable, net	4,575	2,959
Inventories	14,814	14,158
Prepaid expenses and other current assets	1,725	2,925
Deferred income taxes	286	293
Total current assets	48,741	49,559
Property, plant and equipment, net	8,019	7,146
Equity investments	32,711	32,923
Other assets, net	1,132	1,252
Total assets	90,603	90,880
Accounts payable	15,382	13,969
Accrued liabilities	959	852
Total current liabilities	16,341	14,821
Long-term debt	0	0
Deferred income taxes	511	934
Other liabilities	31	67
Stockholders' equity	73,720	75,058
Total liabilities and stockholders' equity	90,603	90,880
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net	(1,253,845)	(1,286,007)
Inventories	0	0
Prepaid expenses and other current assets	0	0
Deferred income taxes	0	0
Total current assets	(1,253,845)	(1,286,007)
Property, plant and equipment, net	0	0
Equity investments	(3,198,362)	(3,073,561)
Other assets, net	(5,986)	(5,964)
Total assets	(4,458,193)	(4,365,532)
Accounts payable	(1,258,221)	(1,274,892)
Accrued liabilities	4,376	(11,115)
Total current liabilities	(1,253,845)	(1,286,007)
Long-term debt	0	0
Deferred income taxes	(5,986)	(5,964)
Other liabilities	0	0
Stockholders' equity	(3,198,362)	(3,073,561)
Total liabilities and stockholders' equity	$ (4,458,193)	$ (4,365,532)

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Segment Information (Additional Information) (Detail)	3 Months Ended
	Mar. 31, 2013 Segment
Segment Reporting [Abstract]
Number of segments	2

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Derivative Instruments (Impact of Derivative Instruments on Income) (Details) (Cost of Sales, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Designated As Fair Value Hedges | Firm Commitment Derivative Items Designated As Hedged Item
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	$ 1,395	$ (11,664)
Designated As Fair Value Hedges | Commodity Forward Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	(1,643)	10,463
Derivatives Not Designated As Hedging Instruments | Commodity Forward Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	$ 7,335	$ 560

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Accounts Receivable

3 Months Ended

Mar. 31, 2013

Accounts Receivable

Accounts Receivable

Accounts receivable consist of the following:

	March 31, 2013			December 31, 2012
Trade customers	$	384,413		$	388,949
Affiliates	297			258
Allowance for doubtful accounts	(11,562		)	(11,172		)
	373,148			378,035
Federal and state taxes	22,480			4,011
Other	11,952			18,113
Accounts receivable, net	$	407,580		$	400,159

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Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Net external sales	$ 864,647	$ 1,034,867
Intersegment sales	70,547	101,845
Income (loss) from operations	194,055	145,625
Depreciation and amortization	35,356	35,394
Other income, net	3,519	1,347
Provision for (benefit from) income taxes	67,946	46,982
Capital expenditures	150,784	64,902
Olefins
Segment Reporting Information [Line Items]
Net external sales	582,845	732,271
Intersegment sales	70,283	101,457
Income (loss) from operations	161,058	129,207
Depreciation and amortization	23,346	23,763
Other income, net	4,010	956
Provision for (benefit from) income taxes	55,477	42,175
Capital expenditures	50,040	17,480
Vinyls
Segment Reporting Information [Line Items]
Net external sales	281,802	302,596
Intersegment sales	264	388
Income (loss) from operations	43,663	21,082
Depreciation and amortization	11,884	11,509
Other income, net	(425)	240
Provision for (benefit from) income taxes	13,720	6,016
Capital expenditures	100,317	46,841
Corporate and Other
Segment Reporting Information [Line Items]
Income (loss) from operations	(10,666)	(4,664)
Depreciation and amortization	126	122
Other income, net	(66)	151
Provision for (benefit from) income taxes	(1,251)	(1,209)
Capital expenditures	427	581
Polyethylene | Olefins
Segment Reporting Information [Line Items]
Net external sales	420,768	445,420
Ethylene, Styrene And Other | Olefins
Segment Reporting Information [Line Items]
Net external sales	162,077	286,851
PVC, Caustic Soda And Other | Vinyls
Segment Reporting Information [Line Items]
Net external sales	195,246	214,383
Building Products | Vinyls
Segment Reporting Information [Line Items]
Net external sales	$ 86,556	$ 88,213

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Long-Term Debt (Revolving Credit Facility) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 400,000
Percentage of commitment on borrowing availability	0.375%
Letters of credit outstanding	16,214
Remaining borrowing capacity	383,786
Minimum
Line of Credit Facility [Line Items]
Increase in credit facility borrowings	25,000
Maximum | Line of Credit
Line of Credit Facility [Line Items]
Increase in credit facility borrowings	$ 150,000
Plus Libor | Minimum | Line of Credit
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	1.75%
Plus Libor | Maximum | Line of Credit
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	2.25%
Plus Base Rate | Minimum | Line of Credit
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	0.25%
Plus Base Rate | Maximum | Line of Credit
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	0.75%

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Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Fair Values of Derivatives Instruments in Consolidated Balance Sheets

The fair values of derivative instruments in the Company's consolidated balance sheets were as follows:

	Derivative Assets
	Balance Sheet Location	Fair Value as of
		March 31, 2013		December 31, 2012
Designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	8,299	$	13,032
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	1,903		1,395
Total derivative assets		$	10,202	$	14,427

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		March 31, 2013		December 31, 2012
Designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	—	$	399
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	9,843		13,295
Total derivative liabilities		$	9,843	$	13,694

Impact of Derivatives Instruments Designated as Fair Value Hedges

The following tables reflect the impact of derivative instruments designated as fair value hedges and the related hedged item on the Company's consolidated statements of operations. For the three months ended March 31, 2013 and 2012, there was no material ineffectiveness with regard to the Company's qualifying fair value hedges.

Derivatives in Fair Value    Hedging Relationships	Location of Gain (Loss) Recognized in  Income on Derivative	Three Months Ended March 31,
		2013			2012
Commodity forward contracts	Cost of sales	$	(1,643	)	$	10,463
Hedged Items in Fair Value    Hedging Relationships	Location of Gain (Loss) Recognized in  Income on Hedged Items	Three Months Ended March 31,
		2013			2012
Firm commitment designated as the hedged item	Cost of sales	$	1,395		$	(11,664	)

Impact of Derivative Instruments Not Designated as Fair Value Hedges

The impact of derivative instruments that have not been designated as hedges on the Company's consolidated statements of operations were as follows:

Derivatives Not Designated as    Hedging Instruments	Location of Gain (Loss) Recognized in  Income on Derivative	Three Months Ended March 31,
		2013		2012
Commodity forward contracts	Cost of sales	$	7,335	$	560

Derivative Assets Subject to and Not Subject to Master Netting Arrangements

The following tables present the Company's derivative assets and derivative liabilities reported on the consolidated balance sheets and derivative assets and derivative liabilities subject to enforceable master netting arrangements.

	Derivative Assets
	March 31, 2013		December 31, 2012
Derivative assets subject to enforceable master netting arrangements	$	—	$	—
Derivative assets not subject to enforceable master netting arrangements	9,057		13,032
Total derivative assets	$	9,057	$	13,032

	March 31, 2013							December 31, 2012
Offsetting of Derivative Assets	Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Assets Presented in the Consolidated Balance Sheet		Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Assets Presented in the Consolidated Balance Sheet
Commodity forward contracts	$	1,145	$	(1,145	)	$	—	$	1,395	$	(1,395	)	$	—

Derivative Liabilities Subject to and Not Subject to Master Netting Arrangements

	Derivative Liabilities
	March 31, 2013		December 31, 2012
Derivative liabilities subject to enforceable master netting arrangements	$	697	$	1,774
Derivative liabilities not subject to enforceable master netting arrangements	8,001		10,525
Total derivative liabilities	$	8,698	$	12,299

	March 31, 2013							December 31, 2012
Offsetting of Derivative Liabilities	Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Liabilities Presented in the Consolidated Balance Sheet
Commodity forward contracts	$	1,842	$	(1,145	)	$	697	$	3,169	$	(1,395	)	$	1,774

	March 31, 2013						December 31, 2012
Derivative Liabilities by Counterparty	Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts Not Offset in the Consolidated Balance Sheet		Net Amount		Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts Not Offset in the Consolidated Balance Sheet		Net Amount
Counterparty A	$	463	$	—	$	463	$	1,128	$	—	$	1,128
Counterparty B	234		—		234		646		—		646
Total	$	697	$	—	$	697	$	1,774	$	—	$	1,774

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Long-Term Debt (Tables)

3 Months Ended

Mar. 31, 2013

Debt Disclosure [Abstract]

Schedule Of Long-Term Debt

Long-term debt consists of the following:

	March 31, 2013		December 31, 2012
3.60% senior notes due 2022	$	248,901	$	248,872
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	$	763,790	$	763,761

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Pension and Post-Retirement Benefit Costs (Components of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 264	$ 254
Interest cost	501	647
Expected return on plan assets	(714)	(620)
Amortization of prior service cost	74	74
Amortization of net loss	429	439
Net periodic benefit cost	554	794
Post-Retirement Healthcare
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest cost	147	185
Expected return on plan assets	0	0
Amortization of prior service cost	21	21
Amortization of net loss	90	44
Net periodic benefit cost	$ 260	$ 252

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Stock-Based Compensation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	$ 1,499	$ 1,651

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Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Summary Of Assets And Liabilities Accounted At Fair Value On A Recurring Basis

The following tables summarize, by level within the fair value hierarchy, the Company's assets and liabilities that were accounted for at fair value on a recurring basis:

	March 31, 2013
	Level 1		Level 2			Total
Derivative instruments
Risk management assets - Commodity forward contracts	$	1,145	$	9,057		$	10,202
Risk management liabilities - Commodity forward contracts	—		(9,843		)	(9,843		)
Firm commitments
Hedged portion of firm commitment	—		(8,299		)	(8,299		)
	December 31, 2012
	Level 1		Level 2			Total
Derivative instruments
Risk management assets - Commodity forward contracts	$	1,395	$	13,032		$	14,427
Risk management liabilities - Commodity forward contracts	—		(13,694		)	(13,694		)
Firm commitments
Hedged portion of firm commitment	—		399			399
Hedged portion of firm commitment	—		(13,032		)	(13,032		)

Summary Of Carrying And Fair Values Of Long-Term Debt

The carrying and fair values of the Company's long-term debt are summarized in the table below. The Company's long-term debt instruments are publicly-traded. A market approach, based upon quotes from financial reporting services, is used to measure the fair value of the Company's long-term debt. Because the Company's long-term debt instruments may not be actively traded, the inputs used to measure the fair value of the Company's long-term debt are classified as Level 2 inputs within the fair value hierarchy.

	March 31, 2013				December 31, 2012
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	248,901	$	252,273	$	248,872	$	251,125
6 ½% senior notes due 2029	100,000		115,999		100,000		119,738
6 ¾% senior notes due 2032	250,000		286,235		250,000		283,168
6 ½% GO Zone Senior Notes Due 2035	89,000		100,367		89,000		102,095
6 ½% IKE Zone Senior Notes Due 2035	65,000		73,302		65,000		74,564
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

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Earnings per Share (Tables)

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Schedule Of Net Income Attributable To Common Stockholders

	Three Months Ended March 31,
	2013			2012
Net income	$	123,347		$	87,813
Less:
Net income attributable to participating securities	(568		)	(610		)
Net income attributable to common shareholders	$	122,779		$	87,203

Reconciliation Of Denominator For Basic And Diluted Earnings Per Share

The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:

	Three Months Ended March 31,
	2013		2012
Weighted average common shares—basic	66,625,536		66,109,297
Plus incremental shares from:
Assumed exercise of options	283,333		449,220
Weighted average common shares—diluted	66,908,869		66,558,517
Earnings per share:
Basic	$	1.84	$	1.32
Diluted	$	1.84	$	1.31

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Current Marketable Securities (Notes)

3 Months Ended

Mar. 31, 2013

Investments, Debt and Equity Securities [Abstract]

Current Marketable Securities

Current Marketable Securities

The Company owned current marketable securities of $94,903 and $124,873 at March 31, 2013 and December 31, 2012, respectively, consisting of short-term corporate debt securities with maturities exceeding three months at the date of acquisition. These debt securities are classified as held-to-maturity and are carried at amortized cost, which approximates their fair value.

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Pension and Post-Retirement Benefit Costs (Tables)

3 Months Ended

Mar. 31, 2013

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Components of Net Periodic Benefit Cost

Components of net periodic benefit cost are as follows:

	Three Months Ended March 31,
	Pension						Post-retirement Healthcare
	2013			2012			2013		2012
Service cost	$	264		$	254		$	2	$	2
Interest cost	501			647			147		185
Expected return on plan assets	(714		)	(620		)	—		—
Amortization of prior service cost	74			74			21		21
Amortization of net loss	429			439			90		44
Net periodic benefit cost	$	554		$	794		$	260	$	252

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Property, Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Property, plant and equipment	$ 1,629,309		$ 1,510,048
Depreciation expense on property, plant and equipment	$ 30,920	$ 30,171

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Earnings per Share (Additional Information) (Detail)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Options excluded from computation of earnings per share, shares	36,388	67,098

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Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 777,887	$ 790,078
Marketable securities	94,903	124,873
Accounts receivable, net	407,580	400,159
Inventories	408,074	399,298
Prepaid expenses and other current assets	14,536	14,700
Deferred income taxes	22,298	22,305
Total current assets	1,725,278	1,751,413
Property, plant and equipment, net	1,629,309	1,510,048
Equity investments	43,914	43,736
Intangible assets, net	48,108	48,292
Deferred charges and other assets	112,616	58,707
Total other assets, net	160,724	106,999
Total assets	3,559,225	3,412,196
Current liabilities
Accounts payable	232,061	217,050
Accrued liabilities	167,754	181,460
Total current liabilities	399,815	398,510
Long-term debt	763,790	763,761
Deferred income taxes	355,975	326,290
Other liabilities	49,854	51,379
Total liabilities	1,569,434	1,539,940
Commitments and contingencies (Notes 6 and 14)
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, 150,000,000 shares authorized; 000 and 67,187,224 shares issued at March 31, 2013 and December 31, 2012, respectively	672	672
Common stock, held in treasury, at cost; 284,493 shares at March 31, 2013 and December 31, 2012	(13,302)	(13,302)
Additional paid-in capital	503,187	496,254
Retained earnings	1,510,266	1,399,472
Accumulated other comprehensive loss	(11,032)	(10,840)
Total stockholders' equity	1,989,791	1,872,256
Total liabilities and stockholders' equity	$ 3,559,225	$ 3,412,196

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Derivative Instruments (Textual) (Detail) (Commodity Forward Contracts, Designated As Fair Value Hedges)	Mar. 31, 2013 gal
Commodity Forward Contracts | Designated As Fair Value Hedges
Derivative [Line Items]
Feedstock forward contracts, in gallons	32,130,000

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Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities
Net income	$ 123,347	$ 87,813
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	35,356	35,394
Provision for (recovery of) doubtful accounts	393	(155)
Amortization of debt issuance costs	365	400
Stock-based compensation expense	1,499	1,651
Loss from disposition of fixed assets	2,387	481
Deferred income taxes	29,466	791
Windfall tax benefits from share-based payment arrangements	(3,844)	(4,481)
Equity in (income) loss of joint ventures	(178)	702
Changes in operating assets and liabilities
Accounts receivable	(7,917)	(37,720)
Inventories	(8,776)	68,372
Prepaid expenses and other current assets	(2,077)	(1,611)
Accounts payable	14,733	(28,138)
Accrued liabilities	(14,670)	(21,647)
Other, net	(53,832)	3,724
Net cash provided by operating activities	116,252	105,576
Cash flows from investing activities
Additions to property, plant and equipment	(150,784)	(64,902)
Proceeds from disposition of assets	2	3
Proceeds from repayment of loan to affiliate	167	167
Proceeds from Sale and Maturity of Marketable Securities	124,873	0
Purchase of securities and other investments	(94,903)	(2,961)
Settlements of derivative instruments	(679)	511
Net cash used for investing activities	(121,324)	(67,182)
Cash flows from financing activities
Dividends paid	(12,553)	(4,914)
Proceeds from exercise of stock options	1,590	480
Utilization of restricted cash	0	30,800
Windfall tax benefits from share-based payment arrangements	3,844	4,481
Net cash provided by financing activities	(7,119)	30,847
Net increase in cash and cash equivalents	(12,191)	69,241
Cash and cash equivalents at beginning of period	790,078	825,901
Cash and cash equivalents at end of period	$ 777,887	$ 895,142

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Accumulated Other Comprehensive Income Reclassifications in AOCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	$ 191,293		$ 134,795
Provision for income taxes	(67,946)		(46,982)
Net income	123,347		87,813
Accumulated Defined Benefit Plans Adjustment | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service costs	(95)	[1]
Net loss	(519)	[1]
Income before income taxes	(614)
Provision for income taxes	236
Net income	$ (378)

[1] These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 8 (Employee Benefits) to the financial statements included in the 2012 Form 10-K.

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Guarantor Disclosures (Tables)

3 Months Ended

Mar. 31, 2013

Guarantees [Abstract]

Condensed Consolidating Financial Information Balance Sheet

Condensed Consolidating Financial Information as of March 31, 2013

	Westlake Chemical Corporation		Guarantor Subsidiaries		Non- Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	742,898	$	7,648	$	27,341	$	—		$	777,887
Marketable securities	94,903		—		—		—			94,903
Accounts receivable, net	12,629		1,644,221		4,575		(1,253,845		)	407,580
Inventories	—		393,260		14,814		—			408,074
Prepaid expenses and other    current assets	223		12,588		1,725		—			14,536
Deferred income taxes	431		21,581		286		—			22,298
Total current assets	851,084		2,079,298		48,741		(1,253,845		)	1,725,278
Property, plant and equipment, net	—		1,621,290		8,019		—			1,629,309
Equity investments	3,143,697		65,868		32,711		(3,198,362		)	43,914
Other assets, net	16,692		148,886		1,132		(5,986		)	160,724
Total assets	$	4,011,473	$	3,915,342	$	90,603	$	(4,458,193	)	$	3,559,225
Current liabilities
Accounts payable	$	1,252,908	$	221,992	$	15,382	$	(1,258,221	)	$	232,061
Accrued liabilities	15,873		146,546		959		4,376			167,754
Total current liabilities	1,268,781		368,538		16,341		(1,253,845		)	399,815
Long-term debt	752,901		10,889		—		—			763,790
Deferred income taxes	—		361,450		511		(5,986		)	355,975
Other liabilities	—		49,823		31		—			49,854
Stockholders' equity	1,989,791		3,124,642		73,720		(3,198,362		)	1,989,791
Total liabilities and stockholders' equity	$	4,011,473	$	3,915,342	$	90,603	$	(4,458,193	)	$	3,559,225

Condensed Consolidating Financial Information as of December 31, 2012

	Westlake Chemical Corporation		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	753,881	$	6,973	$	29,224	$	—		$	790,078
Marketable securities	124,873		—		—		—			124,873
Accounts receivable, net	7,933		1,675,274		2,959		(1,286,007		)	400,159
Inventories	—		385,140		14,158		—			399,298
Prepaid expenses and other    current assets	389		11,386		2,925		—			14,700
Deferred income taxes	431		21,581		293		—			22,305
Total current assets	887,507		2,100,354		49,559		(1,286,007		)	1,751,413
Property, plant and equipment, net	—		1,502,902		7,146		—			1,510,048
Equity investments	3,018,926		65,448		32,923		(3,073,561		)	43,736
Other assets, net	17,033		94,678		1,252		(5,964		)	106,999
Total assets	$	3,923,466	$	3,763,382	$	90,880	$	(4,365,532	)	$	3,412,196
Current liabilities
Accounts payable	$	1,285,530	$	192,443	$	13,969	$	(1,274,892	)	$	217,050
Accrued liabilities	12,808		178,915		852		(11,115		)	181,460
Total current liabilities	1,298,338		371,358		14,821		(1,286,007		)	398,510
Long-term debt	752,872		10,889		—		—			763,761
Deferred income taxes	—		331,320		934		(5,964		)	326,290
Other liabilities	—		51,312		67		—			51,379
Stockholders' equity	1,872,256		2,998,503		75,058		(3,073,561		)	1,872,256
Total liabilities and stockholders' equity	$	3,923,466	$	3,763,382	$	90,880	$	(4,365,532	)	$	3,412,196

Condensed Consolidating Financial Information Statement Of Operations

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	856,085		$	10,540		$	(1,978	)	$	864,647
Cost of sales	—			629,286			9,530			(1,978		)	636,838
Gross profit	—			226,799			1,010			—			227,809
Selling, general and administrative    expenses	510			31,709			1,535			—			33,754
(Loss) income from operations	(510		)	195,090			(525		)	—			194,055
Interest expense	(6,258		)	(23		)	—			—			(6,281		)
Other income (expense), net	4,309			(290		)	(500		)	—			3,519
(Loss) income before income taxes	(2,459		)	194,777			(1,025		)	—			191,293
(Benefit from) provision for income taxes	(874		)	69,051			(231		)	—			67,946
Equity in net income of subsidiaries	124,932			—			—			(124,932		)	—
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Comprehensive income (loss)	$	123,155		$	126,104		$	(1,364	)	$	(124,740	)	$	123,155

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2012

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	1,026,332		$	9,843		$	(1,308	)	$	1,034,867
Cost of sales	—			854,987			8,551			(1,308		)	862,230
Gross profit	—			171,345			1,292			—			172,637
Selling, general and administrative    expenses	505			24,756			1,751			—			27,012
(Loss) income from operations	(505		)	146,589			(459		)	—			145,625
Interest expense	(12,171		)	(6		)	—			—			(12,177		)
Other income (expense), net	3,534			(1,700		)	(487		)	—			1,347
(Loss) income before income taxes	(9,142		)	144,883			(946		)	—			134,795
(Benefit from) provision for income taxes	(3,173		)	50,231			(76		)	—			46,982
Equity in net income of subsidiaries	93,782			—			—			(93,782		)	—
Net income (loss)	$	87,813		$	94,652		$	(870	)	$	(93,782	)	$	87,813
Comprehensive income (loss)	$	105,019		$	111,344		$	(358	)	$	(110,986	)	$	105,019

Condensed Consolidating Financial Information Statement Of Cash Flows

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Adjustments to reconcile net income    (loss) to net cash (used for) provided    by operating activities
Depreciation and amortization	365			34,766			590			—			35,721
Deferred income taxes	(23		)	29,896			(407		)	—			29,466
Net changes in working capital    and other	(129,403		)	(68,474		)	663			124,932			(72,282		)
Net cash (used for) provided by    operating activities	(5,714		)	121,914			52			—			116,252
Cash flows from investing activities
Additions to property, plant and    equipment	—			(149,113		)	(1,671		)	—			(150,784		)
Proceeds from disposition of assets	—			—			2			—			2
Proceeds from repayment of loan    to affiliate	—			—			167			—			167
Proceeds from sales and maturities of    securities	124,873			—			—			—			124,873
Purchase of securities	(94,903		)	—			—			—			(94,903		)
Settlements of derivative instruments	—			(679		)	—			—			(679		)
Net cash provided by (used for)    investing activities	29,970			(149,792		)	(1,502		)	—			(121,324		)
Cash flows from financing activities
Intercompany financing	(28,120		)	28,553			(433		)	—			—
Dividends paid	(12,553		)	—			—			—			(12,553		)
Proceeds from exercise of stock options	1,590			—			—			—			1,590
Windfall tax benefits from share-based    payment arrangements	3,844			—			—			—			3,844
Net cash (used for) provided by    financing activities	(35,239		)	28,553			(433		)	—			(7,119		)
Net (decrease) increase in cash and    cash equivalents	(10,983		)	675			(1,883		)	—			(12,191		)
Cash and cash equivalents at beginning    of period	753,881			6,973			29,224			—			790,078
Cash and cash equivalents at end of period	$	742,898		$	7,648		$	27,341		$	—		$	777,887

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2012

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	87,813		$	94,652		$	(870	)	$	(93,782	)	$	87,813
Adjustments to reconcile net income    (loss) to net cash (used for) provided    by operating activities
Depreciation and amortization	400			34,593			801			—			35,794
Deferred income taxes	(48		)	779			60			—			791
Net changes in working capital    and other	(98,271		)	(12,415		)	(1,918		)	93,782			(18,822		)
Net cash (used for) provided by    operating activities	(10,106		)	117,609			(1,927		)	—			105,576
Cash flows from investing activities
Additions to property, plant and    equipment	—			(64,871		)	(31		)	—			(64,902		)
Proceeds from disposition of assets	—			—			3			—			3
Proceeds from repayment of loan    to affiliate	—			—			167			—			167
Purchase of securities	—			(2,961		)	—			—			(2,961		)
Settlements of derivative instruments	—			511			—			—			511
Net cash (used for) provided by    investing activities	—			(67,321		)	139			—			(67,182		)
Cash flows from financing activities
Intercompany financing	44,883			(49,242		)	4,359			—			—
Dividends paid	(4,914		)	—			—			—			(4,914		)
Proceeds from exercise of stock options	480			—			—			—			480
Utilization of restricted cash	30,800			—			—			—			30,800
Windfall tax benefits from share-based    payment arrangements	4,481			—			—			—			4,481
Net cash provided by (used for)    financing activities	75,730			(49,242		)	4,359			—			30,847
Net increase in cash and cash equivalents	65,624			1,046			2,571			—			69,241
Cash and cash equivalents at beginning    of period	803,320			2,517			20,064			—			825,901
Cash and cash equivalents at end of period	$	868,944		$	3,563		$	22,635		$	—		$	895,142

XML

Subsequent Events Subsequent Events (Details) (Subsequent Event, Pipe and Foundation Group [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 lb
Subsequent Event | Pipe and Foundation Group [Member]
Subsequent Event [Line Items]
Annual production capacity of PVC pipe and fittings	150,000,000
Cash purchase price, including working capital, subject to post-closing adjustments	$ 175,000

XML

Segment Information

3 Months Ended

Mar. 31, 2013

Segment Reporting [Abstract]

Segment Information

Segment Information

The Company operates in two principal business segments: Olefins and Vinyls. These segments are strategic business units that offer a variety of different products. The Company manages each segment separately as each business requires different technology and marketing strategies.

	Three Months Ended March 31,
	2013			2012
Net external sales
Olefins
Polyethylene	$	420,768		$	445,420
Styrene, feedstock and other	162,077			286,851
Total Olefins	582,845			732,271
Vinyls
PVC, caustic soda and other	195,246			214,383
Building products	86,556			88,213
Total Vinyls	281,802			302,596
	$	864,647		$	1,034,867
Intersegment sales
Olefins	$	70,283		$	101,457
Vinyls	264			388
	$	70,547		$	101,845
Income (loss) from operations
Olefins	$	161,058		$	129,207
Vinyls	43,663			21,082
Corporate and other	(10,666		)	(4,664		)
	$	194,055		$	145,625
Depreciation and amortization
Olefins	$	23,346		$	23,763
Vinyls	11,884			11,509
Corporate and other	126			122
	$	35,356		$	35,394
Other income (expense), net
Olefins	$	4,010		$	956
Vinyls	(425		)	240
Corporate and other	(66		)	151
	$	3,519		$	1,347
Provision for (benefit from) income taxes
Olefins	$	55,477		$	42,175
Vinyls	13,720			6,016
Corporate and other	(1,251		)	(1,209		)
	$	67,946		$	46,982

	Three Months Ended March 31,
	2013		2012
Capital expenditures
Olefins	$	50,040	$	17,480
Vinyls	100,317		46,841
Corporate and other	427		581
	$	150,784	$	64,902

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

	Three Months Ended March 31,
	2013			2012
Income from operations	$	194,055		$	145,625
Interest expense	(6,281		)	(12,177		)
Other income, net	3,519			1,347
Income before income taxes	$	191,293		$	134,795

	March 31, 2013		December 31, 2012
Total assets
Olefins	$	1,534,996	$	1,439,308
Vinyls	1,106,500		1,030,912
Corporate and other	917,729		941,976
	$	3,559,225	$	3,412,196

XML

Basis of Financial Statements Basis (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2012 Revision, from operating activities to financing activities	Jun. 30, 2012 Revision, from operating activities to financing activities	Sep. 30, 2012 Revision, from operating activities to financing activities	Dec. 31, 2012 Revision, from operating activities to financing activities	Dec. 31, 2011 Revision, from operating activities to financing activities	Dec. 31, 2010 Revision, from operating activities to financing activities
Windfall tax benefits from share-based payment arrangements	$ 3,844	$ 4,481	$ 4,481	$ 6,468	$ 7,792	$ 11,967	$ 3,361	$ 326

XML

Guarantor Disclosures

3 Months Ended

Mar. 31, 2013

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"). Each Guarantor Subsidiary is 100% owned by Westlake Chemical Corporation. 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 Guarantor Subsidiaries and the remaining subsidiaries that do not guarantee the 3.60% senior notes due 2022 (the "Non-Guarantor Subsidiaries"), together with consolidating adjustments necessary to present the Company's results on a consolidated basis.

Condensed Consolidating Financial Information as of March 31, 2013

	Westlake Chemical Corporation		Guarantor Subsidiaries		Non- Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	742,898	$	7,648	$	27,341	$	—		$	777,887
Marketable securities	94,903		—		—		—			94,903
Accounts receivable, net	12,629		1,644,221		4,575		(1,253,845		)	407,580
Inventories	—		393,260		14,814		—			408,074
Prepaid expenses and other    current assets	223		12,588		1,725		—			14,536
Deferred income taxes	431		21,581		286		—			22,298
Total current assets	851,084		2,079,298		48,741		(1,253,845		)	1,725,278
Property, plant and equipment, net	—		1,621,290		8,019		—			1,629,309
Equity investments	3,143,697		65,868		32,711		(3,198,362		)	43,914
Other assets, net	16,692		148,886		1,132		(5,986		)	160,724
Total assets	$	4,011,473	$	3,915,342	$	90,603	$	(4,458,193	)	$	3,559,225
Current liabilities
Accounts payable	$	1,252,908	$	221,992	$	15,382	$	(1,258,221	)	$	232,061
Accrued liabilities	15,873		146,546		959		4,376			167,754
Total current liabilities	1,268,781		368,538		16,341		(1,253,845		)	399,815
Long-term debt	752,901		10,889		—		—			763,790
Deferred income taxes	—		361,450		511		(5,986		)	355,975
Other liabilities	—		49,823		31		—			49,854
Stockholders' equity	1,989,791		3,124,642		73,720		(3,198,362		)	1,989,791
Total liabilities and stockholders' equity	$	4,011,473	$	3,915,342	$	90,603	$	(4,458,193	)	$	3,559,225

Condensed Consolidating Financial Information as of December 31, 2012

	Westlake Chemical Corporation		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Balance Sheet
Current assets
Cash and cash equivalents	$	753,881	$	6,973	$	29,224	$	—		$	790,078
Marketable securities	124,873		—		—		—			124,873
Accounts receivable, net	7,933		1,675,274		2,959		(1,286,007		)	400,159
Inventories	—		385,140		14,158		—			399,298
Prepaid expenses and other    current assets	389		11,386		2,925		—			14,700
Deferred income taxes	431		21,581		293		—			22,305
Total current assets	887,507		2,100,354		49,559		(1,286,007		)	1,751,413
Property, plant and equipment, net	—		1,502,902		7,146		—			1,510,048
Equity investments	3,018,926		65,448		32,923		(3,073,561		)	43,736
Other assets, net	17,033		94,678		1,252		(5,964		)	106,999
Total assets	$	3,923,466	$	3,763,382	$	90,880	$	(4,365,532	)	$	3,412,196
Current liabilities
Accounts payable	$	1,285,530	$	192,443	$	13,969	$	(1,274,892	)	$	217,050
Accrued liabilities	12,808		178,915		852		(11,115		)	181,460
Total current liabilities	1,298,338		371,358		14,821		(1,286,007		)	398,510
Long-term debt	752,872		10,889		—		—			763,761
Deferred income taxes	—		331,320		934		(5,964		)	326,290
Other liabilities	—		51,312		67		—			51,379
Stockholders' equity	1,872,256		2,998,503		75,058		(3,073,561		)	1,872,256
Total liabilities and stockholders' equity	$	3,923,466	$	3,763,382	$	90,880	$	(4,365,532	)	$	3,412,196

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	856,085		$	10,540		$	(1,978	)	$	864,647
Cost of sales	—			629,286			9,530			(1,978		)	636,838
Gross profit	—			226,799			1,010			—			227,809
Selling, general and administrative    expenses	510			31,709			1,535			—			33,754
(Loss) income from operations	(510		)	195,090			(525		)	—			194,055
Interest expense	(6,258		)	(23		)	—			—			(6,281		)
Other income (expense), net	4,309			(290		)	(500		)	—			3,519
(Loss) income before income taxes	(2,459		)	194,777			(1,025		)	—			191,293
(Benefit from) provision for income taxes	(874		)	69,051			(231		)	—			67,946
Equity in net income of subsidiaries	124,932			—			—			(124,932		)	—
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Comprehensive income (loss)	$	123,155		$	126,104		$	(1,364	)	$	(124,740	)	$	123,155

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2012

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Operations
Net sales	$	—		$	1,026,332		$	9,843		$	(1,308	)	$	1,034,867
Cost of sales	—			854,987			8,551			(1,308		)	862,230
Gross profit	—			171,345			1,292			—			172,637
Selling, general and administrative    expenses	505			24,756			1,751			—			27,012
(Loss) income from operations	(505		)	146,589			(459		)	—			145,625
Interest expense	(12,171		)	(6		)	—			—			(12,177		)
Other income (expense), net	3,534			(1,700		)	(487		)	—			1,347
(Loss) income before income taxes	(9,142		)	144,883			(946		)	—			134,795
(Benefit from) provision for income taxes	(3,173		)	50,231			(76		)	—			46,982
Equity in net income of subsidiaries	93,782			—			—			(93,782		)	—
Net income (loss)	$	87,813		$	94,652		$	(870	)	$	(93,782	)	$	87,813
Comprehensive income (loss)	$	105,019		$	111,344		$	(358	)	$	(110,986	)	$	105,019

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Adjustments to reconcile net income    (loss) to net cash (used for) provided    by operating activities
Depreciation and amortization	365			34,766			590			—			35,721
Deferred income taxes	(23		)	29,896			(407		)	—			29,466
Net changes in working capital    and other	(129,403		)	(68,474		)	663			124,932			(72,282		)
Net cash (used for) provided by    operating activities	(5,714		)	121,914			52			—			116,252
Cash flows from investing activities
Additions to property, plant and    equipment	—			(149,113		)	(1,671		)	—			(150,784		)
Proceeds from disposition of assets	—			—			2			—			2
Proceeds from repayment of loan    to affiliate	—			—			167			—			167
Proceeds from sales and maturities of    securities	124,873			—			—			—			124,873
Purchase of securities	(94,903		)	—			—			—			(94,903		)
Settlements of derivative instruments	—			(679		)	—			—			(679		)
Net cash provided by (used for)    investing activities	29,970			(149,792		)	(1,502		)	—			(121,324		)
Cash flows from financing activities
Intercompany financing	(28,120		)	28,553			(433		)	—			—
Dividends paid	(12,553		)	—			—			—			(12,553		)
Proceeds from exercise of stock options	1,590			—			—			—			1,590
Windfall tax benefits from share-based    payment arrangements	3,844			—			—			—			3,844
Net cash (used for) provided by    financing activities	(35,239		)	28,553			(433		)	—			(7,119		)
Net (decrease) increase in cash and    cash equivalents	(10,983		)	675			(1,883		)	—			(12,191		)
Cash and cash equivalents at beginning    of period	753,881			6,973			29,224			—			790,078
Cash and cash equivalents at end of period	$	742,898		$	7,648		$	27,341		$	—		$	777,887

Condensed Consolidating Financial Information for the Three Months Ended March 31, 2012

	Westlake Chemical Corporation			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	87,813		$	94,652		$	(870	)	$	(93,782	)	$	87,813
Adjustments to reconcile net income    (loss) to net cash (used for) provided    by operating activities
Depreciation and amortization	400			34,593			801			—			35,794
Deferred income taxes	(48		)	779			60			—			791
Net changes in working capital    and other	(98,271		)	(12,415		)	(1,918		)	93,782			(18,822		)
Net cash (used for) provided by    operating activities	(10,106		)	117,609			(1,927		)	—			105,576
Cash flows from investing activities
Additions to property, plant and    equipment	—			(64,871		)	(31		)	—			(64,902		)
Proceeds from disposition of assets	—			—			3			—			3
Proceeds from repayment of loan    to affiliate	—			—			167			—			167
Purchase of securities	—			(2,961		)	—			—			(2,961		)
Settlements of derivative instruments	—			511			—			—			511
Net cash (used for) provided by    investing activities	—			(67,321		)	139			—			(67,182		)
Cash flows from financing activities
Intercompany financing	44,883			(49,242		)	4,359			—			—
Dividends paid	(4,914		)	—			—			—			(4,914		)
Proceeds from exercise of stock options	480			—			—			—			480
Utilization of restricted cash	30,800			—			—			—			30,800
Windfall tax benefits from share-based    payment arrangements	4,481			—			—			—			4,481
Net cash provided by (used for)    financing activities	75,730			(49,242		)	4,359			—			30,847
Net increase in cash and cash equivalents	65,624			1,046			2,571			—			69,241
Cash and cash equivalents at beginning    of period	803,320			2,517			20,064			—			825,901
Cash and cash equivalents at end of period	$	868,944		$	3,563		$	22,635		$	—		$	895,142

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Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 864,647	$ 1,034,867
Cost of sales	636,838	862,230
Gross profit	227,809	172,637
Selling, general and administrative expenses	33,754	27,012
Income from operations	194,055	145,625
Interest expense	(6,281)	(12,177)
Other income (expense), net	3,519	1,347
Income before income taxes	191,293	134,795
Provision for (benefit from) income taxes	67,946	46,982
Equity in net income of subsidiaries	0	0
Net income	123,347	87,813
Comprehensive income (loss)	123,155	105,019
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general and administrative expenses	510	505
Income from operations	(510)	(505)
Interest expense	(6,258)	(12,171)
Other income (expense), net	4,309	3,534
Income before income taxes	(2,459)	(9,142)
Provision for (benefit from) income taxes	(874)	(3,173)
Equity in net income of subsidiaries	124,932	93,782
Net income	123,347	87,813
Comprehensive income (loss)	123,155	105,019
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	856,085	1,026,332
Cost of sales	629,286	854,987
Gross profit	226,799	171,345
Selling, general and administrative expenses	31,709	24,756
Income from operations	195,090	146,589
Interest expense	(23)	(6)
Other income (expense), net	(290)	(1,700)
Income before income taxes	194,777	144,883
Provision for (benefit from) income taxes	69,051	50,231
Equity in net income of subsidiaries	0	0
Net income	125,726	94,652
Comprehensive income (loss)	126,104	111,344
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	10,540	9,843
Cost of sales	9,530	8,551
Gross profit	1,010	1,292
Selling, general and administrative expenses	1,535	1,751
Income from operations	(525)	(459)
Interest expense	0	0
Other income (expense), net	(500)	(487)
Income before income taxes	(1,025)	(946)
Provision for (benefit from) income taxes	(231)	(76)
Equity in net income of subsidiaries	0	0
Net income	(794)	(870)
Comprehensive income (loss)	(1,364)	(358)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(1,978)	(1,308)
Cost of sales	(1,978)	(1,308)
Gross profit	0	0
Selling, general and administrative expenses	0	0
Income from operations	0	0
Interest expense	0	0
Other income (expense), net	0	0
Income before income taxes	0	0
Provision for (benefit from) income taxes	0	0
Equity in net income of subsidiaries	(124,932)	(93,782)
Net income	(124,932)	(93,782)
Comprehensive income (loss)	$ (124,740)	$ (110,986)

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Basis of Financial Statements

3 Months Ended

Mar. 31, 2013

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 have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2012 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, 2012 (the "2012 Form 10-K"), filed with the SEC on February 22, 2013. 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, 2012.

In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of March 31, 2013, its results of operations for the three months ended March 31, 2013 and 2012 and the changes in its cash position for the three months ended March 31, 2013 and 2012.

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, 2013 or any other interim period. The preparation of financial statements in conformity with generally accepted accounting principles in the United States 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.

Revisions

The consolidated statement of cash flows for the three months ended March 31, 2012 has been revised to correct the presentation of windfall tax benefits from share-based compensation of $4,481 in financing activities, instead of operating activities. This revision also impacts the consolidated statements of cash flows for the six months ended June 30, 2012 and nine months ended September 30, 2012 by $6,468 and $7,792, respectively, as well as the years ended December 31, 2010, 2011 and 2012 by $326, $3,361 and $11,967, respectively. The Company has determined that these revisions were immaterial to the Company's previously issued financial statements.

Recent Accounting Pronouncements

Disclosures about Offsetting Assets and Liabilities

In December 2011, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on disclosures for offsetting assets and liabilities. The new accounting guidance requires companies to disclose both gross and net information about (1) instruments and transactions eligible for offset in the statement of financial position, and (2) instruments and transactions subject to an agreement similar to a master netting arrangement. The FASB issued another accounting standards update clarifying the scope of the assets and liabilities offset disclosure requirements in January 2013. The effective date of the disclosure requirements remains unchanged. The Company adopted the new guidance as of January 1, 2013, and the adoption did not have an impact on the Company's consolidated financial position, results of operations or cash flows.

Testing Indefinite-Lived Intangible Assets for Impairment

In July 2012, the FASB issued an accounting standards update to simplify how entities test indefinite-lived intangible assets for impairment and to improve consistency in impairment testing guidance among long-lived asset categories. The new accounting guidance provides an entity with an option to first assess qualitative factors to determine whether it is more likely than not that an indefinite-lived intangible asset is impaired as a basis for determining whether it is necessary to perform the quantitative impairment test under current accounting guidance. If an entity concludes that it is not more likely than not that the indefinite-lived intangible asset is impaired, then the entity is not required to take further action. However, if an entity concludes otherwise, then it is required to determine the fair value of the indefinite-lived intangible asset and perform the quantitative impairment test by comparing the fair value with the carrying amount in accordance with current accounting guidance. Also under this new accounting guidance, an entity has the option to bypass the qualitative assessment for any indefinite-lived intangible asset in any period and proceed directly to performing the quantitative impairment test, but may resume performing the qualitative assessment in any subsequent period. The Company adopted the new indefinite-lived intangible assets test guidance as of January 1, 2013, and the adoption did not have a material impact on the Company's consolidated financial position, results of operations or cash flows.

Reclassifications Out of Accumulated Other Comprehensive Income

In February 2013, the FASB issued an accounting standards update on reporting items reclassified out of accumulated other comprehensive income. The new accounting guidance requires companies to present either parenthetically on the face of the financial statements or in the notes, significant amounts reclassified from each component of accumulated other comprehensive income and the income statement line items affected by the reclassification, with certain exceptions. The Company adopted the new guidance as of January 1, 2013, and the adoption did not have an impact on the Company's consolidated financial position, results of operations or cash flows.

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Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
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	150,000,000	150,000,000
Common stock, shares issued	67,232,590	67,187,224
Common stock, held in treasury	284,493	284,493

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Income Taxes

3 Months Ended

Mar. 31, 2013

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

The effective income tax rate was 35.5% for the three months ended March 31, 2013. The effective income tax rate for the 2013 period was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction. The effective income tax rate was 34.9% for the three months ended March 31, 2012. The effective income tax rate for the 2012 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 was no material change to the total gross unrecognized tax benefits for the three months ended March 31, 2013. Management anticipates reductions to the total amount of unrecognized tax benefits of an additional $621 within the next twelve months due to expiring statutes of limitations.

The Company recognizes penalties and interest accrued related to unrecognized tax benefits in income tax expense. As of March 31, 2013, the Company had no material 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 2007.

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Document and Entity Information	3 Months Ended
	Mar. 31, 2013	Apr. 30, 2013
Document Documentand Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
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		66,777,348

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Earnings per Share

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Earnings per Share

Earnings per Share

The Company has unvested shares of restricted stock and restricted stock units outstanding that are considered participating securities and, therefore, computes basic and diluted earnings per share under the two-class method. Basic earnings per share for the periods are based upon the weighted average number of shares of common stock outstanding during the periods. Diluted earnings per share include the effect of certain stock options.

	Three Months Ended March 31,
	2013			2012
Net income	$	123,347		$	87,813
Less:
Net income attributable to participating securities	(568		)	(610		)
Net income attributable to common shareholders	$	122,779		$	87,203

The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:

	Three Months Ended March 31,
	2013		2012
Weighted average common shares—basic	66,625,536		66,109,297
Plus incremental shares from:
Assumed exercise of options	283,333		449,220
Weighted average common shares—diluted	66,908,869		66,558,517
Earnings per share:
Basic	$	1.84	$	1.32
Diluted	$	1.84	$	1.31

Excluded from the computation of diluted earnings per share are options to purchase 36,388 and 67,098 shares of common stock for the three months ended March 31, 2013 and 2012, 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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Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Net sales	$ 864,647	$ 1,034,867
Cost of sales	636,838	862,230
Gross profit	227,809	172,637
Selling, general and administrative expenses	33,754	27,012
Income from operations	194,055	145,625
Other income (expense)
Interest expense	(6,281)	(12,177)
Other income, net	3,519	1,347
Income before income taxes	191,293	134,795
Provision for income taxes	67,946	46,982
Net income	$ 123,347	$ 87,813
Earnings per share:
Basic	$ 1.84	$ 1.32
Diluted	$ 1.84	$ 1.31
Weighted average shares outstanding:
Basic	66,625,536	66,109,297
Diluted	66,908,869	66,558,517
Dividends per common share	$ 0.1875	$ 0.0738

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Other Assets

3 Months Ended

Mar. 31, 2013

Other Assets [Abstract]

Other Assets

Other Assets

Amortization expense on intangible and other assets of $4,801 and $5,623 is included in the consolidated statements of operations for the three months ended March 31, 2013 and 2012, respectively.

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Property, Plant and Equipment

3 Months Ended

Mar. 31, 2013

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

As of March 31, 2013, the Company had property, plant and equipment, net totaling $1,629,309. 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 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 $30,920 and $30,171 is included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2013 and 2012, respectively.

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Subsequent Events

3 Months Ended

Mar. 31, 2013

Subsequent Events [Abstract]

Subsequent Events

Subsequent Events

In March 2013, the Company announced that it had entered into a definitive agreement with CertainTeed Corporation, a subsidiary of the French public company, Compagnie de Saint-Gobain, to purchase its Pipe and Foundation Group business, a leading producer of PVC pipe and fittings for municipal, water well, mining, agriculture and irrigation applications, with an annual production capacity of approximately 150 million pounds, for a cash purchase price of $175,000, including working capital, subject to post-closing adjustments. This transaction closed on May 1, 2013. No pro forma financial information has been provided as the purchase is not significant to the Company's consolidated financial position or results of operations.

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

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Pension and Post-Retirement Benefit Costs

3 Months Ended

Mar. 31, 2013

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Pension and Post-Retirement Benefit Costs

Pension and Post-Retirement Benefit Costs

Components of net periodic benefit cost are as follows:

	Three Months Ended March 31,
	Pension						Post-retirement Healthcare
	2013			2012			2013		2012
Service cost	$	264		$	254		$	2	$	2
Interest cost	501			647			147		185
Expected return on plan assets	(714		)	(620		)	—		—
Amortization of prior service cost	74			74			21		21
Amortization of net loss	429			439			90		44
Net periodic benefit cost	$	554		$	794		$	260	$	252

The Company contributed $442 to the Salaried pension plan in the first three months of 2012, and contributed $60 and $278 to the Wage pension plan in the first three months of 2013 and 2012, respectively. The Company did not contribute to the Salaried pension plan in the first three months of 2013. The Company expects to make additional contributions of $1,164 to the Salaried pension plan and $870 to the Wage pension plan during the fiscal year ending December 31, 2013.

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Derivative Instruments

3 Months Ended

Mar. 31, 2013

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, were included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2013 and 2012. As of March 31, 2013, the Company had 32,130,000 gallons of feedstock forward contracts designated as fair value hedges.

Gains and losses from changes in the fair value of derivative instruments that are not designated as hedging instruments were included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2013 and 2012.

The exposure on commodity derivatives used for price risk management includes the risk that the counterparty will not pay if the market declines below the established fixed price. In such case, the Company would lose the benefit of the derivative differential on the volume of the commodities covered. In any event, the Company would continue to receive the market price on the actual volume hedged. The Company also bears the risk that it could lose the benefit of market improvements over the fixed derivative price for the term and volume of the derivative instruments (as such improvements would accrue to the benefit of the counterparty).

The fair values of derivative instruments in the Company's consolidated balance sheets were as follows:

	Derivative Assets
	Balance Sheet Location	Fair Value as of
		March 31, 2013		December 31, 2012
Designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	8,299	$	13,032
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	1,903		1,395
Total derivative assets		$	10,202	$	14,427

	Derivative Liabilities
	Balance Sheet Location	Fair Value as of
		March 31, 2013		December 31, 2012
Designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	—	$	399
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	9,843		13,295
Total derivative liabilities		$	9,843	$	13,694

The following tables reflect the impact of derivative instruments designated as fair value hedges and the related hedged item on the Company's consolidated statements of operations. For the three months ended March 31, 2013 and 2012, there was no material ineffectiveness with regard to the Company's qualifying fair value hedges.

Derivatives in Fair Value    Hedging Relationships	Location of Gain (Loss) Recognized in  Income on Derivative	Three Months Ended March 31,
		2013			2012
Commodity forward contracts	Cost of sales	$	(1,643	)	$	10,463
Hedged Items in Fair Value    Hedging Relationships	Location of Gain (Loss) Recognized in  Income on Hedged Items	Three Months Ended March 31,
		2013			2012
Firm commitment designated as the hedged item	Cost of sales	$	1,395		$	(11,664	)

The impact of derivative instruments that have not been designated as hedges on the Company's consolidated statements of operations were as follows:

Derivatives Not Designated as    Hedging Instruments	Location of Gain (Loss) Recognized in  Income on Derivative	Three Months Ended March 31,
		2013		2012
Commodity forward contracts	Cost of sales	$	7,335	$	560

See Note 10 for the fair value of the Company's derivative instruments.

Disclosure about Offsetting Asset and Liability Derivatives

Certain of the Company's derivative instruments are executed under an International Swaps and Derivatives Association ("ISDA") Master Agreement, which permit the Company and a counterparty to aggregate the amounts owed by each party under multiple transactions and replace them with a single net amount payable by one party to the other. The following tables present the Company's derivative assets and derivative liabilities reported on the consolidated balance sheets and derivative assets and derivative liabilities subject to enforceable master netting arrangements.

	Derivative Assets
	March 31, 2013		December 31, 2012
Derivative assets subject to enforceable master netting arrangements	$	—	$	—
Derivative assets not subject to enforceable master netting arrangements	9,057		13,032
Total derivative assets	$	9,057	$	13,032

	March 31, 2013							December 31, 2012
Offsetting of Derivative Assets	Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Assets Presented in the Consolidated Balance Sheet		Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Assets Presented in the Consolidated Balance Sheet
Commodity forward contracts	$	1,145	$	(1,145	)	$	—	$	1,395	$	(1,395	)	$	—

	Derivative Liabilities
	March 31, 2013		December 31, 2012
Derivative liabilities subject to enforceable master netting arrangements	$	697	$	1,774
Derivative liabilities not subject to enforceable master netting arrangements	8,001		10,525
Total derivative liabilities	$	8,698	$	12,299

	March 31, 2013							December 31, 2012
Offsetting of Derivative Liabilities	Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheet			Net Amounts of Liabilities Presented in the Consolidated Balance Sheet
Commodity forward contracts	$	1,842	$	(1,145	)	$	697	$	3,169	$	(1,395	)	$	1,774

	March 31, 2013						December 31, 2012
Derivative Liabilities by Counterparty	Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts Not Offset in the Consolidated Balance Sheet		Net Amount		Net Amounts of Liabilities Presented in the Consolidated Balance Sheet		Gross Amounts Not Offset in the Consolidated Balance Sheet		Net Amount
Counterparty A	$	463	$	—	$	463	$	1,128	$	—	$	1,128
Counterparty B	234		—		234		646		—		646
Total	$	697	$	—	$	697	$	1,774	$	—	$	1,774

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Commitments and Contingencies (Additional Information) (Detail) (USD $) In Thousands, unless otherwise specified	0 Months Ended	1 Months Ended		1 Months Ended	12 Months Ended
	Mar. 17, 2010	Dec. 31, 2007	Mar. 31, 2013	Dec. 31, 2007 Polyone	Dec. 31, 2012 Polyone
Commitments and Contingencies Disclosure [Line Items]
Minimum number of years between arbitrations		5 years
Reimbursement of remediation costs sought by PolyOne	$ 1,400
Percentage of costs related to environmental issues to be paid by PolyOne				100.00%
Costs incurred environmental remediation services					2,687
Agreed cash penalty payment to settle allegations resulting from audit			$ 500

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Long-Term Debt

3 Months Ended

Mar. 31, 2013

Debt Disclosure [Abstract]

Long-Term Debt

Long-Term Debt

Long-term debt consists of the following:

	March 31, 2013		December 31, 2012
3.60% senior notes due 2022	$	248,901	$	248,872
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	$	763,790	$	763,761

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 $150,000) under certain circumstances if lenders agree to commit to such an increase. At March 31, 2013, 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 1.75% to 2.25% or a base rate plus a spread ranging from 0.25% to 0.75%. The revolving credit facility also requires an unused commitment fee of 0.375% 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 September 16, 2016. As of March 31, 2013, the Company had outstanding letters of credit totaling $16,214 and borrowing availability of $383,786 under the revolving credit facility.

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Stock-Based Compensation

3 Months Ended

Mar. 31, 2013

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Stock-Based Compensation

Under the Westlake Chemical Corporation 2004 Omnibus Incentive Plan (the "2004 Plan"), all employees and nonemployee 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 2004 Plan. At the discretion of the administrator of the 2004 Plan, employees and nonemployee 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 2004 Plan was $1,499 and $1,651 for the three months ended March 31, 2013 and 2012, respectively.

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Fair Value Measurements

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

The Company reports certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Under the accounting guidance for fair value measurements, inputs used to measure fair value are classified in one of three levels:

Level 1: Quoted market prices in active markets for identical assets or liabilities.

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data.

Level 3: Unobservable inputs that are not corroborated by market data.

The following tables summarize, by level within the fair value hierarchy, the Company's assets and liabilities that were accounted for at fair value on a recurring basis:

	March 31, 2013
	Level 1		Level 2			Total
Derivative instruments
Risk management assets - Commodity forward contracts	$	1,145	$	9,057		$	10,202
Risk management liabilities - Commodity forward contracts	—		(9,843		)	(9,843		)
Firm commitments
Hedged portion of firm commitment	—		(8,299		)	(8,299		)
	December 31, 2012
	Level 1		Level 2			Total
Derivative instruments
Risk management assets - Commodity forward contracts	$	1,395	$	13,032		$	14,427
Risk management liabilities - Commodity forward contracts	—		(13,694		)	(13,694		)
Firm commitments
Hedged portion of firm commitment	—		399			399
Hedged portion of firm commitment	—		(13,032		)	(13,032		)

The Level 2 measurements are derived using forward curves supplied by industry recognized and unrelated third-party services. There were no transfers in and out of Levels 1 and 2 of the fair value hierarchy for the three months ended March 31, 2013 and 2012.

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 payable and long-term debt, all of which are recorded at carrying value. Further, the Company has current marketable securities that are carried at amortized cost. The amounts reported in the consolidated balance sheets for cash and cash equivalents, current marketable securities, accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of the Company's long-term debt are summarized in the table below. The Company's long-term debt instruments are publicly-traded. A market approach, based upon quotes from financial reporting services, is used to measure the fair value of the Company's long-term debt. Because the Company's long-term debt instruments may not be actively traded, the inputs used to measure the fair value of the Company's long-term debt are classified as Level 2 inputs within the fair value hierarchy.

	March 31, 2013				December 31, 2012
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	248,901	$	252,273	$	248,872	$	251,125
6 ½% senior notes due 2029	100,000		115,999		100,000		119,738
6 ¾% senior notes due 2032	250,000		286,235		250,000		283,168
6 ½% GO Zone Senior Notes Due 2035	89,000		100,367		89,000		102,095
6 ½% IKE Zone Senior Notes Due 2035	65,000		73,302		65,000		74,564
Loan related to tax-exempt waste disposal revenue    bonds due 2027	10,889		10,889		10,889		10,889

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Segment Information (Total Assets) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,559,225	$ 3,412,196
Olefins
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,534,996	1,439,308
Vinyls
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,106,500	1,030,912
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 917,729	$ 941,976

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Guarantor Disclosures (Additional Information) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Ownership interest in guarantor subsidiaries	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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Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting [Abstract]
Income from operations	$ 194,055	$ 145,625
Interest expense	(6,281)	(12,177)
Other income, net	3,519	1,347
Income before income taxes	$ 191,293	$ 134,795

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Segment Information (Tables)

3 Months Ended

Mar. 31, 2013

Segment Reporting [Abstract]

Segment Reporting Information

	Three Months Ended March 31,
	2013			2012
Net external sales
Olefins
Polyethylene	$	420,768		$	445,420
Styrene, feedstock and other	162,077			286,851
Total Olefins	582,845			732,271
Vinyls
PVC, caustic soda and other	195,246			214,383
Building products	86,556			88,213
Total Vinyls	281,802			302,596
	$	864,647		$	1,034,867
Intersegment sales
Olefins	$	70,283		$	101,457
Vinyls	264			388
	$	70,547		$	101,845
Income (loss) from operations
Olefins	$	161,058		$	129,207
Vinyls	43,663			21,082
Corporate and other	(10,666		)	(4,664		)
	$	194,055		$	145,625
Depreciation and amortization
Olefins	$	23,346		$	23,763
Vinyls	11,884			11,509
Corporate and other	126			122
	$	35,356		$	35,394
Other income (expense), net
Olefins	$	4,010		$	956
Vinyls	(425		)	240
Corporate and other	(66		)	151
	$	3,519		$	1,347
Provision for (benefit from) income taxes
Olefins	$	55,477		$	42,175
Vinyls	13,720			6,016
Corporate and other	(1,251		)	(1,209		)
	$	67,946		$	46,982

	Three Months Ended March 31,
	2013		2012
Capital expenditures
Olefins	$	50,040	$	17,480
Vinyls	100,317		46,841
Corporate and other	427		581
	$	150,784	$	64,902

Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes

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

	Three Months Ended March 31,
	2013			2012
Income from operations	$	194,055		$	145,625
Interest expense	(6,281		)	(12,177		)
Other income, net	3,519			1,347
Income before income taxes	$	191,293		$	134,795

Total Assets

	March 31, 2013		December 31, 2012
Total assets
Olefins	$	1,534,996	$	1,439,308
Vinyls	1,106,500		1,030,912
Corporate and other	917,729		941,976
	$	3,559,225	$	3,412,196

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Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended					3 Months Ended					3 Months Ended					3 Months Ended					3 Months Ended					3 Months Ended
	Mar. 31, 2013 3.60% Senior Notes Due 2022	Mar. 31, 2013 3.60% Senior Notes Due 2022 Carrying Value	Dec. 31, 2012 3.60% Senior Notes Due 2022 Carrying Value	Mar. 31, 2013 3.60% Senior Notes Due 2022 Fair Value	Dec. 31, 2012 3.60% Senior Notes Due 2022 Fair Value	Mar. 31, 2013 6 1/2% Senior Notes Due 2029	Mar. 31, 2013 6 1/2% Senior Notes Due 2029 Carrying Value	Dec. 31, 2012 6 1/2% Senior Notes Due 2029 Carrying Value	Mar. 31, 2013 6 1/2% Senior Notes Due 2029 Fair Value	Dec. 31, 2012 6 1/2% Senior Notes Due 2029 Fair Value	Mar. 31, 2013 6 3/4% Senior Notes Due 2032	Mar. 31, 2013 6 3/4% Senior Notes Due 2032 Carrying Value	Dec. 31, 2012 6 3/4% Senior Notes Due 2032 Carrying Value	Mar. 31, 2013 6 3/4% Senior Notes Due 2032 Fair Value	Dec. 31, 2012 6 3/4% Senior Notes Due 2032 Fair Value	Mar. 31, 2013 2035 GO Zone 6 1/2% Notes	Mar. 31, 2013 2035 GO Zone 6 1/2% Notes Carrying Value	Dec. 31, 2012 2035 GO Zone 6 1/2% Notes Carrying Value	Mar. 31, 2013 2035 GO Zone 6 1/2% Notes Fair Value	Dec. 31, 2012 2035 GO Zone 6 1/2% Notes Fair Value	Mar. 31, 2013 2035 IKE Zone 6 1/2% Notes	Mar. 31, 2013 2035 IKE Zone 6 1/2% Notes Carrying Value	Dec. 31, 2012 2035 IKE Zone 6 1/2% Notes Carrying Value	Mar. 31, 2013 2035 IKE Zone 6 1/2% Notes Fair Value	Dec. 31, 2012 2035 IKE Zone 6 1/2% Notes Fair Value	Mar. 31, 2013 Loan Related To Tax-Exempt Waste Disposal Revenue Bonds Due 2027	Mar. 31, 2013 Loan Related To Tax-Exempt Waste Disposal Revenue Bonds Due 2027 Carrying Value	Dec. 31, 2012 Loan Related To Tax-Exempt Waste Disposal Revenue Bonds Due 2027 Carrying Value	Mar. 31, 2013 Loan Related To Tax-Exempt Waste Disposal Revenue Bonds Due 2027 Fair Value	Dec. 31, 2012 Loan Related To Tax-Exempt Waste Disposal Revenue Bonds Due 2027 Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity	2022					2029					2032					2035					2035					2027
Stated interest rate	3.60%					6.50%					6.75%					6.50%					6.50%
Senior notes		$ 248,901	$ 248,872	$ 252,273	$ 251,125		$ 100,000	$ 100,000	$ 115,999	$ 119,738		$ 250,000	$ 250,000	$ 286,235	$ 283,168		$ 89,000	$ 89,000	$ 100,367	$ 102,095		$ 65,000	$ 65,000	$ 73,302	$ 74,564
Loans																											$ 10,889	$ 10,889	$ 10,889	$ 10,889

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Commitments and Contingencies

3 Months Ended

Mar. 31, 2013

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, 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.

Contract Disputes with Goodrich and PolyOne. In connection with the 1990 and 1997 acquisitions of the Goodrich Corporation ("Goodrich") chemical manufacturing complex in Calvert City, Kentucky, Goodrich agreed to indemnify the Company for any liabilities related to preexisting contamination at the complex. 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 complex, 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 complex 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 $2,687 in 2012. 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.

Administrative Proceedings. There are several administrative proceedings in Kentucky involving the Company, Goodrich and PolyOne related to the same manufacturing complex 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 complex. 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 pursuant to an Administrative Settlement Agreement ("AOC"), which became effective on December 9, 2009. See "Change in Regulatory Regime" below. The proceedings have been postponed. Periodic status conferences will be held to evaluate whether additional proceedings will be required.

Change in Regulatory Regime. In May 2009, the Cabinet sent a letter to the U.S. Environmental Protection Agency ("EPA") requesting the EPA's assistance in addressing contamination at the Calvert City site under the U.S. Comprehensive Environmental Response, Compensation, and Liability Act ("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. During the past two years, 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, the AOC and an order to conduct the RIFS. The parties submitted and received EPA approval for a RIFS work plan to implement the AOC. The parties are currently conducting the RIFS.

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 complex 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.

EPA Audit of Ethylene Units in Lake Charles. During 2007, the EPA conducted an audit of the Company's ethylene units in Lake Charles, Louisiana, with a focus on leak detection and repair ("LDAR"). As a result of the audit, the EPA brought allegations that the Company had violated certain environmental laws and regulations pertaining to LDAR. The Company has agreed to settle this matter, subject to court approval, by paying a cash penalty of $500 and has recorded an accrual in such amount.

In addition to the matters described above, the Company is involved in various routine legal proceedings incidental to the conduct of its business. The Company 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.

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Accounts Receivable (Tables)

3 Months Ended

Mar. 31, 2013

Schedule Of Accounts Receivable

Accounts receivable consist of the following:

	March 31, 2013			December 31, 2012
Trade customers	$	384,413		$	388,949
Affiliates	297			258
Allowance for doubtful accounts	(11,562		)	(11,172		)
	373,148			378,035
Federal and state taxes	22,480			4,011
Other	11,952			18,113
Accounts receivable, net	$	407,580		$	400,159

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Derivative Instruments (Derivative Liabilities Reported on Balance Sheet and Subject to Master Netting Arrangements) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Offsetting Liabilities [Line Items]
Derivative liabilities not subject to enforceable master netting arrangements	$ 8,001	$ 10,525
Total derivative liabilities	8,698	12,299
Net Amount	697	1,774
Subject to Master Netting | Commodity Forward Contracts
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	1,842	3,169
Gross Amounts Offset in the Consolidated Balance Sheet	(1,145)	(1,395)
Net Amount	697	1,774
Gross Amounts Not Offset in the Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	697	1,774
Subject to Master Netting | Commodity Forward Contracts | Counterparty A
Offsetting Liabilities [Line Items]
Net Amount	463	1,128
Gross Amounts Not Offset in the Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	463	1,128
Subject to Master Netting | Commodity Forward Contracts | Counterparty B
Offsetting Liabilities [Line Items]
Net Amount	234	646
Gross Amounts Not Offset in the Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 234	$ 646

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Other Assets (Additional Information) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Assets [Abstract]
Amortization expense on intangible assets, included in other assets	$ 4,801	$ 5,623

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Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement of Stockholders' Equity [Abstract]
Net income	$ 123,347	$ 87,813
Pension and other post-retirement benefits liability
Amortization of benefits liability	614	578
Income tax provision on pension and other post-retirement benefits liability	(236)	(222)
Foreign currency translation adjustments	(570)	512
Available-for-sale investments
Unrealized holding gains (losses) on investments	0	25,473
Income tax provision on unrealized holding gains	0	(9,135)
Other comprehensive income (loss)	(192)	17,206
Comprehensive income	$ 123,155	$ 105,019

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Inventories

3 Months Ended

Mar. 31, 2013

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories consist of the following:

	March 31, 2013		December 31, 2012
Finished products	$	198,639	$	200,940
Feedstock, additives and chemicals	154,304		143,912
Materials and supplies	55,131		54,446
Inventories	$	408,074	$	399,298

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Accumulated Other Comprehensive Income Changes in AOCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	$ (10,840)
Other comprehensive loss before reclassifications	(570)
Amounts reclassified from accumulated other comprehensive loss	378
Net other comprehensive income (loss) for the period	(192)
Accumulated other comprehensive income (loss), ending balance	(11,032)
Benefits Liability, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(16,351)
Other comprehensive loss before reclassifications	0
Amounts reclassified from accumulated other comprehensive loss	378
Net other comprehensive income (loss) for the period	378
Accumulated other comprehensive income (loss), ending balance	(15,973)
Cumulative Foreign Currency Exchange
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	5,511
Other comprehensive loss before reclassifications	(570)
Amounts reclassified from accumulated other comprehensive loss	0
Net other comprehensive income (loss) for the period	(570)
Accumulated other comprehensive income (loss), ending balance	$ 4,941

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Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Net income	$ 123,347	$ 87,813
Depreciation and amortization	35,721	35,794
Deferred income taxes	29,466	791
Net changes in working capital and other	(72,282)	(18,822)
Net cash provided by operating activities	116,252	105,576
Additions to property, plant and equipment	(150,784)	(64,902)
Proceeds from disposition of assets	2	3
Proceeds from repayment of loan to affiliate	167	167
Proceeds from sales of equity securities			124,873
Purchase of securities and other investments	(94,903)	(2,961)
Settlements of derivative instruments	(679)	511
Net cash used for investing activities	(121,324)	(67,182)
Intercompany financing	0	0
Dividends paid	(12,553)	(4,914)
Proceeds from exercise of stock options	1,590	480
Utilization of restricted cash	0	30,800
Windfall tax benefits from share-based payment arrangements	3,844	4,481
Net cash provided by financing activities	(7,119)	30,847
Net increase in cash and cash equivalents	(12,191)	69,241
Cash and cash equivalents at beginning of period	790,078	825,901	825,901
Cash and cash equivalents at end of period	777,887	895,142
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Net income	123,347	87,813
Depreciation and amortization	365	400
Deferred income taxes	(23)	(48)
Net changes in working capital and other	(129,403)	(98,271)
Net cash provided by operating activities	(5,714)	(10,106)
Additions to property, plant and equipment	0	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities			124,873
Purchase of securities and other investments	(94,903)	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	29,970	0
Intercompany financing	(28,120)	44,883
Dividends paid	(12,553)	(4,914)
Proceeds from exercise of stock options	1,590	480
Utilization of restricted cash		30,800
Windfall tax benefits from share-based payment arrangements	3,844	4,481
Net cash provided by financing activities	(35,239)	75,730
Net increase in cash and cash equivalents	(10,983)	65,624
Cash and cash equivalents at beginning of period	753,881	803,320	803,320
Cash and cash equivalents at end of period	742,898	868,944
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	125,726	94,652
Depreciation and amortization	34,766	34,593
Deferred income taxes	29,896	779
Net changes in working capital and other	(68,474)	(12,415)
Net cash provided by operating activities	121,914	117,609
Additions to property, plant and equipment	(149,113)	(64,871)
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities			0
Purchase of securities and other investments	0	(2,961)
Settlements of derivative instruments	(679)	511
Net cash used for investing activities	(149,792)	(67,321)
Intercompany financing	28,553	(49,242)
Dividends paid	0	0
Proceeds from exercise of stock options	0	0
Utilization of restricted cash		0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	28,553	(49,242)
Net increase in cash and cash equivalents	675	1,046
Cash and cash equivalents at beginning of period	6,973	2,517	2,517
Cash and cash equivalents at end of period	7,648	3,563
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	(794)	(870)
Depreciation and amortization	590	801
Deferred income taxes	(407)	60
Net changes in working capital and other	663	(1,918)
Net cash provided by operating activities	52	(1,927)
Additions to property, plant and equipment	(1,671)	(31)
Proceeds from disposition of assets	2	3
Proceeds from repayment of loan to affiliate	167	167
Proceeds from sales of equity securities	0
Purchase of securities and other investments	0	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	(1,502)	139
Intercompany financing	(433)	4,359
Dividends paid	0	0
Proceeds from exercise of stock options	0	0
Utilization of restricted cash		0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	(433)	4,359
Net increase in cash and cash equivalents	(1,883)	2,571
Cash and cash equivalents at beginning of period	29,224	20,064	20,064
Cash and cash equivalents at end of period	27,341	22,635
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income	(124,932)	(93,782)
Depreciation and amortization	0	0
Deferred income taxes	0	0
Net changes in working capital and other	124,932	93,782
Net cash provided by operating activities	0	0
Additions to property, plant and equipment	0	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities	0
Purchase of securities and other investments	0	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	0	0
Intercompany financing		0
Dividends paid	0	0
Proceeds from exercise of stock options	0	0
Utilization of restricted cash		0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	$ 0	$ 0

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Inventories (Tables)

3 Months Ended

Mar. 31, 2013

Inventory Disclosure [Abstract]

Schedule Of Inventory

Inventories consist of the following:

	March 31, 2013		December 31, 2012
Finished products	$	198,639	$	200,940
Feedstock, additives and chemicals	154,304		143,912
Materials and supplies	55,131		54,446
Inventories	$	408,074	$	399,298

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Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts Receivable, Net [Abstract]
Trade customers	$ 384,413	$ 388,949
Affiliates	297	258
Allowance for doubtful accounts	(11,562)	(11,172)
Receivables from trade customers and affiliates, net	373,148	378,035
Federal and state taxes	22,480	4,011
Other	11,952	18,113
Accounts receivable, net	$ 407,580	$ 400,159

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Accumulated Other Comprehensive Income

3 Months Ended

Mar. 31, 2013

Equity [Abstract]

Accumulated Other Comprehensive Income

Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2013 were as follows:

	Benefits Liability, Net of Tax			Cumulative Foreign Currency Exchange			Total
Balances at December 31, 2012	$	(16,351	)	$	5,511		$	(10,840	)
Other comprehensive loss before reclassifications	—			(570		)	(570		)
Amounts reclassified from accumulated other comprehensive loss	378			—			378
Net other comprehensive income (loss) for the period	378			(570		)	(192		)
Balances at March 31, 2013	$	(15,973	)	$	4,941		$	(11,032	)

The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three months ended March 31, 2013:

Details about Accumulated Other Comprehensive    Income (Loss) Components	Location of Reclassification (Income (Expense)) in Consolidated Statements of Operations	Three Months Ended March 31, 2013
Amortization of pension and other post-retirement items
Prior service costs	(1)	$	(95	)
Net loss	(1)	(519		)
		(614		)
	Provision for income taxes	236
Total reclassifications for the period		$	(378	)

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(1) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 8 (Employee Benefits) to the financial statements included in the 2012 Form 10-K.