Westlake (WLK) 10-Q7 Nov 132013 Q3 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2013	Nov. 01, 2013
Document Documentand Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'WLK	'
Entity Registrant Name	'WESTLAKE CHEMICAL CORP	'
Entity Central Index Key	'0001262823	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	66,770,803

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets	'	'
Cash and cash equivalents	$591,556	$790,078
Marketable Securities, Current	125,597	124,873
Accounts receivable, net	433,025	400,159
Inventories	451,571	399,298
Prepaid expenses and other current assets	18,809	14,700
Deferred income taxes	22,293	22,305
Total current assets	1,642,851	1,751,413
Property, plant and equipment, net	1,952,918	1,510,048
Equity investments	65,488	43,736
Other assets, net	'	'
Intangible assets, net	159,376	48,292
Deferred charges and other assets	102,816	58,707
Total other assets, net	262,192	106,999
Total assets	3,923,449	3,412,196
Current liabilities	'	'
Accounts payable	258,067	217,050
Accrued liabilities	174,619	181,460
Total current liabilities	432,686	398,510
Long-term debt	763,849	763,761
Deferred income taxes	410,166	326,290
Other liabilities	51,691	51,379
Total liabilities	1,658,392	1,539,940
Commitments and contingencies (Notes 7 and 16)	'	'
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; 67,276,761 and 67,187,224 shares issued at September 30, 2013 and December 31, 2012, respectively	673	672
Common stock, held in treasury, at cost; 506,525 and 284,493 shares at September 30, 2013 and December 31, 2012, respectively	-32,711	-13,302
Additional paid-in capital	509,295	496,254
Retained earnings	1,798,721	1,399,472
Accumulated other comprehensive loss	-10,921	-10,840
Total stockholders' equity	2,265,057	1,872,256
Total liabilities and stockholders' equity	$3,923,449	$3,412,196

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 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	67,276,761	67,187,224
Common stock, held in treasury	506,525	284,493

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]	'	'	'	'
Net sales	$1,004,165	$821,175	$2,807,859	$2,770,000
Cost of sales	699,694	648,996	2,002,092	2,223,288
Gross profit	304,471	172,179	805,767	546,712
Selling, general and administrative expenses	37,869	29,662	109,883	87,592
Income from operations	266,602	142,517	695,884	459,120
Other income (expense)	'	'	'	'
Interest expense	-3,297	-11,934	-14,921	-35,682
Debt retirement costs	0	-7,082	0	-7,082
Gain from sales of equity securities	0	477	0	16,429
Other (expense) income, net	-287	1,222	3,137	3,676
Income before income taxes	263,018	125,200	684,100	436,461
Provision for income taxes	92,728	38,236	244,647	146,183
Net income	$170,290	$86,964	$439,453	$290,278
Earnings per share:	'	'	'	'
Basic	$2.55	$1.30	$6.57	$4.36
Diluted	$2.54	$1.30	$6.54	$4.33
Weighted average shares outstanding:	'	'	'	'
Basic	66,628,747	66,311,958	66,628,027	66,240,225
Diluted	66,905,554	66,656,760	66,903,379	66,621,520
Dividends per common share	$0.23	$0.19	$0.60	$0.34

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income	$170,290	$86,964	$439,453	$290,278
Pension and other post-retirement benefits liability	'	'	'	'
Pension and other post-retirement reserves adjustment (excluding amortization)	-489	72	-978	142
Amortization of benefits liability	695	584	2,004	1,747
Income tax provision on pension and other post-retirement benefits liability	-78	-252	-394	-725
Foreign currency translation adjustments	546	865	-844	928
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	0	521	0	0
Available-for-sale investments	'	'	'	'
Unrealized holding gains (losses) on investments	205	339	205	14,582
Income tax provision on unrealized holding gains	-74	-121	-74	-5,229
Reclassification of net realized gain to net income	0	-306	0	-10,538
Other comprehensive income (loss)	805	1,702	-81	907
Comprehensive income	$171,095	$88,666	$439,372	$291,185

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities	'	'
Net income	$439,453	$290,278
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	116,294	109,601
Provision for (recovery of) doubtful accounts	3,600	-536
Amortization of debt issuance costs	1,093	1,149
Stock-based compensation expense	4,804	4,640
Loss from disposition of fixed assets	4,679	1,945
Gain from sales of equity securities	0	-16,429
Write off of Deferred Debt Issuance Cost	0	1,277
Deferred income taxes	83,443	4,385
Windfall tax benefits from share-based payment arrangements	-5,056	-7,792
Equity in (income) loss of joint ventures	1,586	2,567
Changes in operating assets and liabilities	'	'
Accounts receivable	-18,874	13,732
Inventories	-26,325	119,240
Prepaid expenses and other current assets	-5,038	-1,977
Accounts payable	19,518	-35,651
Accrued liabilities	-15,755	20,077
Other, net	-55,922	-13,675
Net cash provided by operating activities	547,500	492,831
Cash flows from investing activities	'	'
Acquisition of business	-178,309	0
Additions to equity investments	-23,338	0
Additions to property, plant and equipment	-498,290	-235,463
Construction of assets pending sale-leaseback	-136	-5,484
Proceeds from disposition of assets	78	435
Proceeds from repayment of loan to affiliate	167	763
Proceeds from sale and maturities of securities	239,764	47,655
Purchase of securities and other investments	-232,286	-2,961
Settlements of derivative instruments	-2,297	471
Net cash used for investing activities	-694,647	-194,584
Cash flows from financing activities	'	'
Capitalized debt issuance costs	0	-2,221
Dividends paid	-40,204	-22,345
Proceeds from Issuance of Long-term Debt	0	248,818
Proceeds from exercise of stock options	3,182	6,627
Repayments of Long-term Debt	0	250,000
Repurchase of common stock for treasury	-19,409	-10,784
Utilization of restricted cash	0	96,433
Windfall tax benefits from share-based payment arrangements	5,056	7,792
Net cash provided by financing activities	-51,375	74,320
Net increase in cash and cash equivalents	-198,522	372,567
Cash and cash equivalents at beginning of period	790,078	825,901
Cash and cash equivalents at end of period	$591,556	$1,198,468

Basis_of_Financial_Statements

Basis of Financial Statements	9 Months Ended
Basis of Financial Statements	Sep. 30, 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 ("U.S. GAAP") 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 September 30, 2013, its results of operations for the three and nine months ended September 30, 2013 and 2012 and the changes in its cash position for the nine months ended September 30, 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 U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
	Revisions
	The consolidated statement of cash flows for the nine months ended September 30, 2012 has been revised to correct the presentation of windfall tax benefits from share-based compensation of $7,792 in financing activities, instead of operating activities. The Company has determined that this revision was 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.

Current_Marketable_Securities

Current Marketable Securities	9 Months Ended
	Sep. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'
Current Marketable Securities	'
	Current Marketable Securities
	The Company’s investments in current marketable securities were classified as follows:


		September 30,			December 31,
		2013			2012
	Available-for-sale securities	$	120,602		$	—

	Held-to-maturity securities	4,995			124,873

	Marketable securities	$	125,597		$	124,873

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


			September 30, 2013
			Cost			Gross		Gross			Fair Value
						Unrealized		Unrealized
						Gains		Losses (1)
	Debt securities
	Corporate bonds		$	11,888		$	191	$	(21	)	$	12,058

	U.S. government debt (2)		26,400			23		(6		)	26,417

	Asset-backed securities		82,109			27		(9		)	82,127

	Total available-for-sale securities		$	120,397		$	241	$	(36	)	$	120,602

	_____________

	-1	All unrealized loss positions were held at a loss for less than 12 months.

	-2	U.S. Treasury obligations, U.S. government agency obligations and U.S government agency mortgage-backed securities.
	As of September 30, 2013, net unrealized gains on the Company's available-for-sale securities of $131, net of income tax expense of $74, were recorded in accumulated other comprehensive income. See Note 10 for the fair value hierarchy of the Company’s available-for-sale securities.
	As of September 30, 2013, the corporate bond securities held by the Company had maturities between one to five years, U.S. government debt securities, excluding U.S. government agency mortgage-backed securities, had maturities of less than one year, U.S. government agency mortgage-backed securities had maturities between four to 26 years and asset-backed securities had maturities between two to five years.



	Held-to-Maturity Securities
	The Company owned held-to-maturity securities of $4,995 and $124,873 at September 30, 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 carried at amortized cost, which approximates their fair value.

Accounts_Receivable

Accounts Receivable	9 Months Ended
	Sep. 30, 2013
Accounts Receivable, Net [Abstract]	'
Accounts Receivable	'
	Accounts Receivable
	Accounts receivable consist of the following:


		September 30,			December 31,
		2013			2012
	Trade customers	$	404,678		$	388,949

	Affiliates	333			258

	Allowance for doubtful accounts	(9,832		)	(11,172		)
		395,179			378,035

	Federal and state taxes	20,421			4,011

	Other	17,425			18,113

	Accounts receivable, net	$	433,025		$	400,159

Inventories

Inventories	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories consist of the following:


		September 30,		December 31,
		2013		2012
	Finished products	$	198,762	$	200,940

	Feedstock, additives and chemicals	194,558		143,912

	Materials and supplies	58,251		54,446

	Inventories	$	451,571	$	399,298

Property_Plant_and_Equipment

Property, Plant and Equipment	9 Months Ended
Property, Plant and Equipment	Sep. 30, 2013
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment	'
	Property, Plant and Equipment
	As of September 30, 2013, the Company had property, plant and equipment, net totaling $1,952,918. The Company assesses these assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, including when negative conditions such as significant current or projected operating losses exist. Other factors considered by the Company when determining if an impairment assessment is necessary include, but are not limited to, significant changes or projected changes in supply and demand fundamentals (which would have a negative impact on operating rates or margins), new technological developments, new competitors with significant raw material or other cost advantages, adverse changes associated with the U.S. and world economies and uncertainties associated with governmental actions. Long-lived assets assessed for impairment are grouped at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities.
	Depreciation expense on property, plant and equipment of $32,460 and $30,055 is included in cost of sales in the consolidated statements of operations for the three months ended September 30, 2013 and 2012, respectively. Depreciation expense on property, plant and equipment of $95,995 and $90,615 is included in cost of sales in the consolidated statements of operations for the nine months ended September 30, 2013 and 2012, respectively.

Other_Assets

Other Assets	9 Months Ended
Other Assets	Sep. 30, 2013
Other Assets [Abstract]	'
Other Assets	'
	Other Assets
	Amortization expense on intangible and other assets of $8,634 and $8,717 is included in the consolidated statements of operations for the three months ended September 30, 2013 and 2012, respectively. Amortization expense on intangible and other assets of $21,392 and $20,135 is included in the consolidated statements of operations for the nine months ended September 30, 2013 and 2012, respectively.

LongTerm_Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	Long-Term Debt
	Long-term debt consists of the following:


		September 30,		December 31,
		2013		2012
	3.60% senior notes due 2022	$	248,960	$	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	$	763,849	$	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 September 30, 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 September 30, 2013, the Company had outstanding letters of credit totaling $16,921 and borrowing availability of $383,079 under the revolving credit facility.

StockBased_Compensation

Stock-Based Compensation	9 Months Ended
Stock-Based Compensation	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Compensation	'
	Stock-Based Compensation
	Under the Westlake Chemical Corporation 2013 Omnibus Incentive Plan (as amended and restated, the "2013 Plan"), all employees and 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 2013 Plan. At the discretion of the administrator of the 2013 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 2013 Plan was $1,680 and $1,515 for the three months ended September 30, 2013 and 2012, respectively, and $4,804 and $4,640 for the nine months ended September 30, 2013 and 2012, respectively.

Derivative_Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 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 and nine months ended September 30, 2013 and 2012. As of September 30, 2013, the Company had 10,710,000 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 and nine months ended September 30, 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).
	Disclosures related to the Company's derivative assets and derivative liabilities subject to enforceable master netting arrangements have not been presented as they are not material to the Company's consolidated balance sheets at September 30, 2013 and December 31, 2012.
	The fair values of derivative instruments in the Company's consolidated balance sheets were as follows:


		Derivative Assets
		Balance Sheet Location	Fair Value as of
			September 30,			December 31,
			2013			2012
	Designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	$	3,208		$	13,032

	Not designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	2,541			1,395

	Total derivative assets		$	5,749		$	14,427



		Derivative Liabilities
		Balance Sheet Location	Fair Value as of
			September 30,			December 31,
			2013			2012
	Designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	$	—		$	399

	Not designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	2,090			13,295

	Total derivative liabilities		$	2,090		$	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 and nine months ended September 30, 2013 and 2012, there was no material ineffectiveness with regard to the Company's qualifying fair value hedges.


	Derivatives in Fair Value	Location of Gain (Loss)	Three Months Ended September 30,						Nine Months Ended September 30,
	Hedging Relationships	Recognized in
		Income on Derivative	2013			2012			2013			2012
	Commodity forward contracts	Cost of sales	$	(232	)	$	(515	)	$	(342	)	$	12,345


	Hedged Items in Fair Value	Location of Gain (Loss)	Three Months Ended September 30,						Nine Months Ended September 30,
	Hedging Relationships	Recognized in
		Income on Hedged Items	2013			2012			2013			2012
	Firm commitment designated	Cost of sales	$	236		$	515		$	15		$	(13,546	)
	as the hedged item
	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	Location of Gain (Loss)	Three Months Ended September 30,						Nine Months Ended September 30,
	Hedging Instruments	Recognized in
		Income on Derivative	2013			2012			2013			2012
	Commodity forward contracts	Cost of sales	$	4,854		$	249		$	9,897		$	(783	)

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

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 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:


		30-Sep-13
		Level 1			Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	1,808		$	3,941		$	5,749

	Risk management liabilities - Commodity forward contracts	(74		)	(2,016		)	(2,090		)
	Firm commitments
	Hedged portion of firm commitment	—			(3,208		)	(3,208		)

	Marketable securities
	Available-for-sale securities	14,998			105,604			120,602


		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 for the Company's commodity contracts are derived using forward curves supplied by industry-recognized and unrelated third-party services. The Level 2 measurements for the Company's available-for-sale securities are derived using market-based pricing provided by unrelated third-party services.
	There were no transfers in and out of Levels 1 and 2 of the fair value hierarchy for the nine months ended September 30, 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. The amounts reported in the consolidated balance sheets for cash and cash equivalents, 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.


		30-Sep-13						December 31, 2012
		Carrying			Fair			Carrying			Fair
		Value			Value			Value			Value
	3.60% senior notes due 2022	$	248,960		$	238,228		$	248,872		$	251,125

	6 ½% senior notes due 2029	100,000			107,800			100,000			119,738

	6 ¾% senior notes due 2032	250,000			267,465			250,000			283,168

	6 ½% GO Zone Senior Notes Due 2035	89,000			94,209			89,000			102,095

	6 ½% IKE Zone Senior Notes Due 2035	65,000			68,804			65,000			74,564

	Loan related to tax-exempt waste disposal revenue	10,889			10,889			10,889			10,889
	bonds due 2027

Income_Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The effective income tax rate was 35.8% for the nine months ended September 30, 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 33.5% for the nine months ended September 30, 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, partially offset by state income taxes.
	There was no material change to the total gross unrecognized tax benefits for the nine months ended September 30, 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 September 30, 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.

Earnings_per_Share

Earnings per Share	9 Months Ended
	Sep. 30, 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 September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
	Net income	$	170,290		$	86,964		$	439,453		$	290,278

	Less:
	Net income attributable to participating securities	(587		)	(452		)	(1,691		)	(1,682		)
	Net income attributable to common shareholders	$	169,703		$	86,512		$	437,762		$	288,596

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


		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
	Weighted average common shares—basic	66,628,747			66,311,958			66,628,027			66,240,225

	Plus incremental shares from:
	Assumed exercise of options	276,807			344,802			275,352			381,295

	Weighted average common shares—diluted	66,905,554			66,656,760			66,903,379			66,621,520


	Earnings per share:
	Basic	$	2.55		$	1.3		$	6.57		$	4.36

	Diluted	$	2.54		$	1.3		$	6.54		$	4.33

	Excluded from the computation of diluted earnings per share are options to purchase 68,662 and 168,362 shares of common stock for the three months ended September 30, 2013 and 2012, respectively, and 57,759 and 293,062 shares of common stock for the nine months ended September 30, 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.

Pension_and_PostRetirement_Ben

Pension and Post-Retirement Benefit Costs	9 Months Ended
	Sep. 30, 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 September 30,										Nine Months Ended September 30,
		Pension						Post-retirement				Pension						Post-retirement
								Healthcare										Healthcare
		2013			2012			2013		2012		2013			2012			2013		2012
	Service cost	$	275		$	250		$	2	$	2	$	815		$	754		$	7	$	7

	Interest cost	515			645			147		185		1,531			1,936			442		555

	Expected return on plan assets	(713		)	(623		)	—		—		(2,140		)	(1,867		)	—		—

	Amortization of prior	74			74			21		21		223			223			63		63
	service cost
	Amortization of net loss	510			445			90		44		1,449			1,329			269		132

	Net periodic benefit cost	$	661		$	791		$	260	$	252	$	1,878		$	2,375		$	781	$	757

	The Company contributed $776 and $2,283 to the Salaried pension plan in the first nine months of 2013 and 2012, respectively, and contributed $640 and $1,542 to the Wage pension plan in the first nine months of 2013 and 2012, respectively. The Company expects to make additional contributions of $388 to the Salaried pension plan and $290 to the Wage pension plan during the fiscal year ending December 31, 2013.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Accumulated Other Comprehensive Income	'
	Accumulated Other Comprehensive Loss
	Changes in accumulated other comprehensive income (loss) by component for the nine months ended September 30, 2013 were as follows:


			Benefits				Cumulative				Net Unrealized		Total
			Liability,				Foreign				Holding Gains
			Net of Tax				Currency				on Investments,
							Exchange				Net of Tax
	Balances at December 31, 2012		$	(16,351	)		$	5,511			$	—	$	(10,840	)

	Other comprehensive (loss) income before		(601		)		(844		)		131		(1,314		)
	reclassifications
	Amounts reclassified from accumulated other		1,233				—				—		1,233
	comprehensive loss
	Net other comprehensive income (loss) for the period		632				(844		)		131		(81		)

	Balances at September 30, 2013		$	(15,719	)		$	4,667			$	131	$	(10,921	)

	The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three and nine months ended September 30, 2013:


	Details about Accumulated Other Comprehensive		Location of Reclassification		Three Months Ended September 30, 2013				Nine Months Ended September 30, 2013
	Income (Loss) Components		(Income (Expense)) in
			Consolidated Statements
			of Operations
	Amortization of pension and other post-retirement items
	Prior service costs		-1		$	(95	)		$	(286	)
	Net loss		-1		(600		)		(1,718		)
					(695		)		(2,004		)
			Provision for income taxes		267				771

	Total reclassifications for the period				$	(428	)		$	(1,233	)
	_____________

	-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.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Acquisitions	'
	Acquisitions
	On May 1, 2013, the Company acquired assets comprising CertainTeed Corporation's Pipe and Foundation Group ("PFG") business and accounted for the asset acquisition as a business combination. The PFG acquisition includes the PVC pipe, fittings, profiles and foundation business and associated facilities in Lodi, California and McPherson, Kansas with production capacity of approximately 150 million pounds per year. The Company also acquired technologies and intellectual property for the production of a number of specialized products, including Certa-Lok® restrained joint pipe and Yelomine™ branded products for a variety of end-market applications. The Company's management believes that this acquisition will enhance the Company's building products portfolio by adding new specialty product lines and supporting technology.
	The closing date purchase price of $178,309 was paid with available cash on hand. This amount is subject to a post-closing working capital adjustment. The acquisition is being accounted for under the acquisition method of accounting. The assets acquired and liabilities assumed and the results of operations of this acquired business are included in the Vinyls segment. The revenue and earnings of the PFG business included in the consolidated statement of operations since the acquisition date have not been presented separately as they are not material to the Company's consolidated statements of operations for the three and nine months ended September 30, 2013. The pro forma impact of this business combination has not been presented as it is not material to the Company's consolidated statements of operations for the three and nine months ended September 30, 2013 and 2012.
	For the nine months ended September 30, 2013, the Company recognized $1,124 of acquisition-related costs. These costs are included in selling, general and administrative expenses in the consolidated statement of operations for the nine months ended September 30, 2013.
	The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition. The final determination of fair value for certain assets and liabilities will be completed as soon as the information necessary to complete the analysis is obtained. These amounts will be finalized as soon as possible, but no later than one year from the acquisition date.


	Fair value of consideration transferred:
	Cash	$	178,309


	Preliminary allocation of consideration transferred to net assets acquired:
	Accounts receivable (1)	$	17,695

	Inventories	25,948

	Property, plant and equipment	31,261

	Intangible assets:
	Customer relationships (weighted average life of 15 years)	57,600

	Trademarks	5,200

	Developed technology (weighted average life of 15 years)	18,900

	Other intangibles (weighted average life of two years)	300

	Current liabilities	(10,595		)
	Other liabilities	(26		)
	Total identifiable net assets	146,283

	Goodwill (2)	32,026

	Consideration transferred	$	178,309

	_____________

	-1	The fair value of accounts receivable acquired is $17,695, with the gross contractual amount being $17,772. The Company expects $77 to be uncollectible.

	-2	The goodwill recognized is primarily attributable to synergies from the Company's vinyls integration strategy expected to arise from the Company's PFG acquisition, as well as intangible assets that do not qualify for separate recognition. The goodwill is expected to be deductible for income tax purposes. The Company has not yet completed the process of assigning the goodwill to its reporting units.
	Supplemental Noncash Investing Cash Flow Information
	In conjunction with the acquisition, liabilities assumed consist of the following:


	Fair value of assets acquired	$	188,930

	Cash paid	(178,309		)
	Liabilities assumed	$	10,621

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 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. On July 12, 2013, the parties submitted separate draft RIFS reports to the EPA.
	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.
	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.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 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 September 30,								Nine Months Ended September 30,
			2013				2012				2013				2012
	Net external sales
	Olefins
	Polyethylene		$	460,105			$	431,614			$	1,294,566			$	1,275,057

	Styrene, feedstock and other		219,234				108,171				590,959				669,718

	Total Olefins		679,339				539,785				1,885,525				1,944,775

	Vinyls
	PVC, caustic soda and other		212,041				191,310				612,391				569,316

	Building products		112,785				90,080				309,943				255,909

	Total Vinyls		324,826				281,390				922,334				825,225

			$	1,004,165			$	821,175			$	2,807,859			$	2,770,000


	Intersegment sales
	Olefins		$	85,454			$	76,771			$	230,607			$	247,671

	Vinyls		403				391				1,111				1,167

			$	85,857			$	77,162			$	231,718			$	248,838


	Income (loss) from operations
	Olefins		$	237,239			$	124,452			$	585,958			$	409,550

	Vinyls		39,554				24,059				136,123				67,724

	Corporate and other		(10,191		)		(5,994		)		(26,197		)		(18,154		)
			$	266,602			$	142,517			$	695,884			$	459,120


	Depreciation and amortization
	Olefins		$	26,515			$	27,070			$	76,415			$	74,903

	Vinyls		14,089				11,232				39,507				34,330

	Corporate and other		124				122				372				368

			$	40,728			$	38,424			$	116,294			$	109,601


	Other income (expense), net
	Olefins		$	728			$	806			$	5,889			$	2,764

	Vinyls		(742		)		146				(1,687		)		115

	Corporate and other		(273		)		270				(1,065		)		797

			$	(287	)		$	1,222			$	3,137			$	3,676


	Provision for (benefit from) income taxes
	Olefins		$	82,553			$	36,092			$	208,170			$	130,612

Vinyls		10,710				6,556				44,120				18,989

Corporate and other		(535		)		(4,412		)		(7,643		)		(3,418		)
		$	92,728			$	38,236			$	244,647			$	146,183




		Three Months Ended September 30,								Nine Months Ended September 30,
		2013				2012				2013				2012
Capital expenditures
Olefins		$	27,577			$	46,867			$	105,656			$	92,168

Vinyls		172,565				47,001				391,864				139,836

Corporate and other		276				1,027				770				3,459

		$	200,418			$	94,895			$	498,290			$	235,463

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


		Three Months Ended September 30,								Nine Months Ended September 30,
		2013				2012				2013				2012
Income from operations		$	266,602			$	142,517			$	695,884			$	459,120

Interest expense		(3,297		)		(11,934		)		(14,921		)		(35,682		)
Debt retirement costs		—				(7,082		)		—				(7,082		)

Gain from sales of equity securities		—				477				—				16,429

Other (expense) income, net		(287		)		1,222				3,137				3,676

Income before income taxes		$	263,018			$	125,200			$	684,100			$	436,461



		September 30,				December 31,
		2013				2012
Total assets
Olefins		$	1,560,303			$	1,439,308

Vinyls		1,577,549				1,030,912

Corporate and other		785,597				941,976

		$	3,923,449			$	3,412,196

Goodwill_Goodwill

Goodwill Goodwill	9 Months Ended
	Sep. 30, 2013
Goodwill [Abstract]	'
Goodwill	'
	Goodwill
	The changes in the carrying amount of goodwill for the nine months ended September 30, 2013 were as follows:


		Olefins Segment		Vinyls Segment		Total
	Balance at December 31, 2012	$	29,990	$	—	$	29,990

	Goodwill acquired during the period	—		32,026		32,026

	Balance at September 30, 2013	$	29,990	$	32,026	$	62,016

Subsequent_Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	Subsequent events were evaluated through the date on which the financial statements were issued.

Guarantor_Disclosures

Guarantor Disclosures	9 Months Ended
	Sep. 30, 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 September 30, 2013



			Westlake			Guarantor			Non-			Eliminations				Consolidated
			Chemical			Subsidiaries			Guarantor
			Corporation						Subsidiaries
	Balance Sheet
	Current assets
	Cash and cash equivalents		$	560,261		$	4,494		$	26,801		$	—			$	591,556

	Marketable securities		125,597			—			—			—				125,597

	Accounts receivable, net		5,373			694,473			5,489			(272,310		)		433,025

	Inventories		—			435,540			16,031			—				451,571

	Prepaid expenses and other		468			15,931			2,410			—				18,809
	current assets
	Deferred income taxes		431			21,744			118			—				22,293

	Total current assets		692,130			1,172,182			50,849			(272,310		)		1,642,851

	Property, plant and equipment, net		—			1,945,405			7,513			—				1,952,918

	Equity investments		2,635,954			98,823			31,634			(2,700,923		)		65,488

	Other assets, net		16,969			251,703			506			(6,986		)		262,192

	Total assets		$	3,345,053		$	3,468,113		$	90,502		$	(2,980,219	)		$	3,923,449

	Current liabilities
	Accounts payable		$	311,357		$	220,106		$	4,322		$	(277,718	)		$	258,067

	Accrued liabilities		15,679			151,654			1,878			5,408				174,619

	Total current liabilities		327,036			371,760			6,200			(272,310		)		432,686

	Long-term debt		752,960			10,889			—			—				763,849

	Deferred income taxes		—			416,404			748			(6,986		)		410,166

	Other liabilities		—			51,640			51			—				51,691

	Stockholders' equity		2,265,057			2,617,420			83,503			(2,700,923		)		2,265,057

	Total liabilities and		$	3,345,053		$	3,468,113		$	90,502		$	(2,980,219	)		$	3,923,449
	stockholders' equity

	Condensed Consolidating Financial Information as of December 31, 2012


			Westlake			Guarantor			Non-Guarantor			Eliminations				Consolidated
			Chemical			Subsidiaries			Subsidiaries
			Corporation
	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		389			11,386			2,925			—				14,700
current assets
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		$	3,923,466		$	3,763,382		$	90,880		$	(4,365,532	)		$	3,412,196
stockholders' equity


Condensed Consolidating Financial Information for the Three Months Ended September 30, 2013


		Westlake			Guarantor			Non-			Eliminations				Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
Statement of Operations
Net sales		$	—		$	992,413		$	13,337		$	(1,585	)		$	1,004,165

Cost of sales		—			689,388			11,891			(1,585		)		699,694

Gross profit		—			303,025			1,446			—				304,471

Selling, general and administrative		514			35,714			1,641			—				37,869
expenses
(Loss) income from operations		(514		)	267,311			(195		)	—				266,602

Interest expense		(3,292		)	(5		)	—			—				(3,297		)

Other income (expense), net		3,585			(3,821		)	(51		)	—				(287		)

(Loss) income before income taxes		(221		)	263,485			(246		)	—				263,018

(Benefit from) provision for income taxes		(70		)	92,849			(51		)	—				92,728

Equity in net income of subsidiaries		170,441			—			—			(170,441		)		—

Net income (loss)		$	170,290		$	170,636		$	(195	)	$	(170,441	)		$	170,290

Comprehensive income		$	171,095		$	170,764		$	351		$	(171,115	)		$	171,095



Condensed Consolidating Financial Information for the Three Months Ended September 30, 2012




		Westlake			Guarantor			Non-			Eliminations				Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
Statement of Operations
Net sales		$	—		$	809,164		$	13,876		$	(1,865	)		$	821,175

Cost of sales		—			638,892			11,969			(1,865		)		648,996

Gross profit		—			170,272			1,907			—				172,179

Selling, general and administrative		498			27,601			1,563			—				29,662
expenses
(Loss) income from operations		(498		)	142,671			344			—				142,517

Interest expense		(11,919		)	(15		)	—			—				(11,934		)

Debt retirement costs		(7,082		)	—			—			—				(7,082		)

Gain from sales of equity securities		—			477			—			—				477

Other income (expense), net		4,556			(2,744		)	(590		)	—				1,222

(Loss) income before income taxes		(14,943		)	140,389			(246		)	—				125,200

(Benefit from) provision for income taxes		(4,498		)	42,596			138			—				38,236

Equity in net income of subsidiaries		97,409			—			—			(97,409		)		—

Net income (loss)		$	86,964		$	97,793		$	(384	)	$	(97,409	)		$	86,964

Comprehensive income		$	88,666		$	98,109		$	481		$	(98,590	)		$	88,666


Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2013


		Westlake			Guarantor			Non-			Eliminations				Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
Statement of Operations
Net sales		$	—		$	2,777,280		$	37,561		$	(6,982	)		$	2,807,859

Cost of sales		—			1,976,131			32,943			(6,982		)		2,002,092

Gross profit		—			801,149			4,618			—				805,767

Selling, general and administrative		1,576			103,478			4,829			—				109,883
expenses
(Loss) income from operations		(1,576		)	697,671			(211		)	—				695,884

Interest expense		(14,882		)	(39		)	—			—				(14,921		)

Other income (expense), net		7,490			(2,473		)	(1,880		)	—				3,137

(Loss) income before income taxes		(8,968		)	695,159			(2,091		)	—				684,100

(Benefit from) provision for income taxes		(3,202		)	248,301			(452		)	—				244,647

Equity in net income of subsidiaries		445,219			—			—			(445,219		)		—

Net income (loss)		$	439,453		$	446,858		$	(1,639	)	$	(445,219	)		$	439,453

Comprehensive income (loss)		$	439,372		$	447,490		$	(2,483	)	$	(445,007	)		$	439,372



Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2012


		Westlake			Guarantor			Non-			Eliminations				Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
Statement of Operations
Net sales		$	—		$	2,738,180		$	37,154		$	(5,334	)		$	2,770,000

Cost of sales		—			2,197,300			31,322			(5,334		)		2,223,288

Gross profit		—			540,880			5,832			—				546,712

Selling, general and administrative		1,500			81,288			4,804			—				87,592
expenses
(Loss) income from operations		(1,500		)	459,592			1,028			—				459,120

Interest expense		(35,652		)	(30		)	—			—				(35,682		)

Debt retirement costs		(7,082		)	—			—			—				(7,082		)

Gain from sales of equity securities		1			16,428			—			—				16,429

Other income (expense), net		12,044			(5,724		)	(2,644		)	—				3,676

(Loss) income before income taxes		(32,189		)	470,266			(1,616		)	—				436,461

(Benefit from) provision for income taxes		(11,105		)	158,228			(940		)	—				146,183

Equity in net income of subsidiaries		311,362			—			—			(311,362		)		—

Net income (loss)		$	290,278		$	312,038		$	(676	)	$	(311,362	)		$	290,278

Comprehensive income		$	291,185		$	312,017		$	252		$	(312,269	)		$	291,185


Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2013


		Westlake			Guarantor			Non-			Eliminations				Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)		$	439,453		$	446,858		$	(1,639	)	$	(445,219	)		$	439,453

Adjustments to reconcile net income
(loss) to net cash (used for) provided
by operating activities
Depreciation and amortization		1,094			114,432			1,861			—				117,387

Deferred income taxes		(1,102		)	84,532			13			—				83,443

Net changes in working capital		(458,336		)	(87,330		)	7,664			445,219				(92,783		)
and other
Net cash (used for) provided by		(18,891		)	558,492			7,899			—				547,500
operating activities
Cash flows from investing activities
Acquisition of business		—			(178,309		)	—			—				(178,309		)

Additions to equity investments		—			(23,338		)	—			—				(23,338		)

Additions to property, plant and		—			(496,027		)	(2,263		)	—				(498,290		)
equipment
Construction of assets pending		—			(136		)	—			—				(136		)
sale-leaseback
Proceeds from disposition of assets		—			6			72			—				78

Proceeds from repayment of loan		—			—			167			—				167
to affiliate
Proceeds from sales and maturities of		239,764			—			—			—				239,764
securities
Purchase of securities		(232,286		)	—			—			—				(232,286		)

Settlements of derivative instruments		—			(2,297		)	—			—				(2,297		)

Net cash provided by (used for)		7,478			(700,101		)	(2,024		)	—				(694,647		)
investing activities
Cash flows from financing activities
Intercompany financing		(130,832		)	139,130			(8,298		)	—				—

Dividends paid		(40,204		)	—			—			—				(40,204		)

Proceeds from exercise of stock options		3,182			—			—			—				3,182

Repurchase of common stock for treasury		(19,409		)	—			—			—				(19,409		)

Windfall tax benefits from share-based		5,056			—			—			—				5,056
payment arrangements
Net cash (used for) provided by		(182,207		)	139,130			(8,298		)	—				(51,375		)
financing activities
Net decrease in cash and cash equivalents		(193,620		)	(2,479		)	(2,423		)	—				(198,522		)

Cash and cash equivalents at beginning		753,881			6,973			29,224			—				790,078
of period
Cash and cash equivalents at end of period		$	560,261		$	4,494		$	26,801		$	—			$	591,556


Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2012


		Westlake			Guarantor			Non-			Eliminations				Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)		$	290,278		$	312,038		$	(676	)	$	(311,362	)		$	290,278

Adjustments to reconcile net income
(loss) to net cash (used for) provided
by operating activities
Depreciation and amortization		1,149			107,191			2,410			—				110,750

Deferred income taxes		(176		)	3,932			629			—				4,385

Net changes in working capital		(317,955		)	95,909			(1,898		)	311,362				87,418
and other
Net cash (used for) provided by		(26,704		)	519,070			465			—				492,831
operating activities
Cash flows from investing activities
Additions to property, plant and		—			(234,713		)	(750		)	—				(235,463		)
equipment
Construction of assets pending		—			(5,484		)	—			—				(5,484		)
sale-leaseback
Proceeds from disposition of assets		—			414			21			—				435

Proceeds from repayment of loan		—			—			763			—				763
to affiliate
Proceeds from sales of equity securities		3			47,652			—			—				47,655

Purchase of securities		—			(2,961		)	—			—				(2,961		)

Settlements of derivative instruments		—			471			—			—				471

Net cash provided by (used for)		3			(194,621		)	34			—				(194,584		)
investing activities
Cash flows from financing activities
Intercompany financing		317,185			(321,273		)	4,088			—				—

Capitalized debt issuance costs		(2,221		)	—			—			—				(2,221		)

Dividends paid		(22,345		)	—			—			—				(22,345		)

Proceeds from borrowings		248,818			—			—			—				248,818

Proceeds from exercise of stock options		6,627			—			—			—				6,627

Repayment of borrowings		(250,000		)	—			—			—				(250,000		)

Repurchase of common stock for treasury		(10,784		)	—			—			—				(10,784		)

Utilization of restricted cash		96,433			—			—			—				96,433

Windfall tax benefits from share-based		7,792			—			—			—				7,792
payment arrangements
Net cash provided by (used for)		391,505			(321,273		)	4,088			—				74,320
financing activities
Net increase in cash and cash equivalents		364,804			3,176			4,587			—				372,567

Cash and cash equivalents at beginning		803,320			2,517			20,064			—				825,901
of period
Cash and cash equivalents at end of period		$	1,168,124		$	5,693		$	24,651		$	—			$	1,198,468

Basis_of_Financial_Statements_

Basis of Financial Statements (Policies)	9 Months Ended
Basis of Financial Statements (Policies)	Sep. 30, 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 ("U.S. GAAP") 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 September 30, 2013, its results of operations for the three and nine months ended September 30, 2013 and 2012 and the changes in its cash position for the nine months ended September 30, 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 U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	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.

Current_Marketable_Securities_

Current Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'
Marketable Securities	'
	The Company’s investments in current marketable securities were classified as follows:


		September 30,			December 31,
		2013			2012
	Available-for-sale securities	$	120,602		$	—

	Held-to-maturity securities	4,995			124,873

	Marketable securities	$	125,597		$	124,873

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


			September 30, 2013
			Cost			Gross		Gross			Fair Value
						Unrealized		Unrealized
						Gains		Losses (1)
	Debt securities
	Corporate bonds		$	11,888		$	191	$	(21	)	$	12,058

	U.S. government debt (2)		26,400			23		(6		)	26,417

	Asset-backed securities		82,109			27		(9		)	82,127

	Total available-for-sale securities		$	120,397		$	241	$	(36	)	$	120,602

	_____________

	-1	All unrealized loss positions were held at a loss for less than 12 months.

	-2	U.S. Treasury obligations, U.S. government agency obligations and U.S government agency mortgage-backed securities.
Schedule of Realized Gain (Loss)	'

Accounts_Receivable_Tables

Accounts Receivable (Tables)	9 Months Ended
	Sep. 30, 2013
Accounts Receivable, Net [Abstract]	'
Schedule Of Accounts Receivable	'
	Accounts receivable consist of the following:


		September 30,			December 31,
		2013			2012
	Trade customers	$	404,678		$	388,949

	Affiliates	333			258

	Allowance for doubtful accounts	(9,832		)	(11,172		)
		395,179			378,035

	Federal and state taxes	20,421			4,011

	Other	17,425			18,113

	Accounts receivable, net	$	433,025		$	400,159

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Schedule Of Inventory	'
	Inventories consist of the following:


		September 30,		December 31,
		2013		2012
	Finished products	$	198,762	$	200,940

	Feedstock, additives and chemicals	194,558		143,912

	Materials and supplies	58,251		54,446

	Inventories	$	451,571	$	399,298

LongTerm_Debt_Tables

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Schedule Of Long-Term Debt	'
	Long-term debt consists of the following:


		September 30,		December 31,
		2013		2012
	3.60% senior notes due 2022	$	248,960	$	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	$	763,849	$	763,761

Derivative_Instruments_Tables

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 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
			September 30,			December 31,
			2013			2012
	Designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	$	3,208		$	13,032

	Not designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	2,541			1,395

	Total derivative assets		$	5,749		$	14,427



		Derivative Liabilities
		Balance Sheet Location	Fair Value as of
			September 30,			December 31,
			2013			2012
	Designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	$	—		$	399

	Not designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	2,090			13,295

	Total derivative liabilities		$	2,090		$	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 and nine months ended September 30, 2013 and 2012, there was no material ineffectiveness with regard to the Company's qualifying fair value hedges.


	Derivatives in Fair Value	Location of Gain (Loss)	Three Months Ended September 30,						Nine Months Ended September 30,
	Hedging Relationships	Recognized in
		Income on Derivative	2013			2012			2013			2012
	Commodity forward contracts	Cost of sales	$	(232	)	$	(515	)	$	(342	)	$	12,345


	Hedged Items in Fair Value	Location of Gain (Loss)	Three Months Ended September 30,						Nine Months Ended September 30,
	Hedging Relationships	Recognized in
		Income on Hedged Items	2013			2012			2013			2012
	Firm commitment designated	Cost of sales	$	236		$	515		$	15		$	(13,546	)
	as the hedged item
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	Location of Gain (Loss)	Three Months Ended September 30,						Nine Months Ended September 30,
	Hedging Instruments	Recognized in
		Income on Derivative	2013			2012			2013			2012
	Commodity forward contracts	Cost of sales	$	4,854		$	249		$	9,897		$	(783	)

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 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:


		30-Sep-13
		Level 1			Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	1,808		$	3,941		$	5,749

	Risk management liabilities - Commodity forward contracts	(74		)	(2,016		)	(2,090		)
	Firm commitments
	Hedged portion of firm commitment	—			(3,208		)	(3,208		)

	Marketable securities
	Available-for-sale securities	14,998			105,604			120,602


		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.


		30-Sep-13						December 31, 2012
		Carrying			Fair			Carrying			Fair
		Value			Value			Value			Value
	3.60% senior notes due 2022	$	248,960		$	238,228		$	248,872		$	251,125

	6 ½% senior notes due 2029	100,000			107,800			100,000			119,738

	6 ¾% senior notes due 2032	250,000			267,465			250,000			283,168

	6 ½% GO Zone Senior Notes Due 2035	89,000			94,209			89,000			102,095

	6 ½% IKE Zone Senior Notes Due 2035	65,000			68,804			65,000			74,564

	Loan related to tax-exempt waste disposal revenue	10,889			10,889			10,889			10,889
	bonds due 2027

Earnings_per_Share_Tables

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Schedule Of Net Income Attributable To Common Stockholders	'


		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
	Net income	$	170,290		$	86,964		$	439,453		$	290,278

	Less:
	Net income attributable to participating securities	(587		)	(452		)	(1,691		)	(1,682		)
	Net income attributable to common shareholders	$	169,703		$	86,512		$	437,762		$	288,596

Reconciliation Of Denominator For Basic And Diluted Earnings Per Share	'
	The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:


		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
	Weighted average common shares—basic	66,628,747			66,311,958			66,628,027			66,240,225

	Plus incremental shares from:
	Assumed exercise of options	276,807			344,802			275,352			381,295

	Weighted average common shares—diluted	66,905,554			66,656,760			66,903,379			66,621,520


	Earnings per share:
	Basic	$	2.55		$	1.3		$	6.57		$	4.36

	Diluted	$	2.54		$	1.3		$	6.54		$	4.33

Pension_and_PostRetirement_Ben1

Pension and Post-Retirement Benefit Costs (Tables)	9 Months Ended
	Sep. 30, 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 September 30,										Nine Months Ended September 30,
		Pension						Post-retirement				Pension						Post-retirement
								Healthcare										Healthcare
		2013			2012			2013		2012		2013			2012			2013		2012
	Service cost	$	275		$	250		$	2	$	2	$	815		$	754		$	7	$	7

	Interest cost	515			645			147		185		1,531			1,936			442		555

	Expected return on plan assets	(713		)	(623		)	—		—		(2,140		)	(1,867		)	—		—

	Amortization of prior	74			74			21		21		223			223			63		63
	service cost
	Amortization of net loss	510			445			90		44		1,449			1,329			269		132

	Net periodic benefit cost	$	661		$	791		$	260	$	252	$	1,878		$	2,375		$	781	$	757

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	'
	Changes in accumulated other comprehensive income (loss) by component for the nine months ended September 30, 2013 were as follows:


			Benefits				Cumulative				Net Unrealized		Total
			Liability,				Foreign				Holding Gains
			Net of Tax				Currency				on Investments,
							Exchange				Net of Tax
	Balances at December 31, 2012		$	(16,351	)		$	5,511			$	—	$	(10,840	)

	Other comprehensive (loss) income before		(601		)		(844		)		131		(1,314		)
	reclassifications
	Amounts reclassified from accumulated other		1,233				—				—		1,233
	comprehensive loss
	Net other comprehensive income (loss) for the period		632				(844		)		131		(81		)

	Balances at September 30, 2013		$	(15,719	)		$	4,667			$	131	$	(10,921	)

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 and nine months ended September 30, 2013:


	Details about Accumulated Other Comprehensive		Location of Reclassification		Three Months Ended September 30, 2013				Nine Months Ended September 30, 2013
	Income (Loss) Components		(Income (Expense)) in
			Consolidated Statements
			of Operations
	Amortization of pension and other post-retirement items
	Prior service costs		-1		$	(95	)		$	(286	)
	Net loss		-1		(600		)		(1,718		)
					(695		)		(2,004		)
			Provision for income taxes		267				771

	Total reclassifications for the period				$	(428	)		$	(1,233	)
	_____________

	-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.

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	'


	Fair value of consideration transferred:
	Cash	$	178,309


	Preliminary allocation of consideration transferred to net assets acquired:
	Accounts receivable (1)	$	17,695

	Inventories	25,948

	Property, plant and equipment	31,261

	Intangible assets:
	Customer relationships (weighted average life of 15 years)	57,600

	Trademarks	5,200

	Developed technology (weighted average life of 15 years)	18,900

	Other intangibles (weighted average life of two years)	300

	Current liabilities	(10,595		)
	Other liabilities	(26		)
	Total identifiable net assets	146,283

	Goodwill (2)	32,026

	Consideration transferred	$	178,309

Supplemental Noncash Investing Cash Flow Information	'
	In conjunction with the acquisition, liabilities assumed consist of the following:


	Fair value of assets acquired	$	188,930

	Cash paid	(178,309		)
	Liabilities assumed	$	10,621

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Segment Reporting Information	'


			Three Months Ended September 30,								Nine Months Ended September 30,
			2013				2012				2013				2012
	Net external sales
	Olefins
	Polyethylene		$	460,105			$	431,614			$	1,294,566			$	1,275,057

	Styrene, feedstock and other		219,234				108,171				590,959				669,718

	Total Olefins		679,339				539,785				1,885,525				1,944,775

	Vinyls
	PVC, caustic soda and other		212,041				191,310				612,391				569,316

	Building products		112,785				90,080				309,943				255,909

	Total Vinyls		324,826				281,390				922,334				825,225

			$	1,004,165			$	821,175			$	2,807,859			$	2,770,000


	Intersegment sales
	Olefins		$	85,454			$	76,771			$	230,607			$	247,671

	Vinyls		403				391				1,111				1,167

			$	85,857			$	77,162			$	231,718			$	248,838


	Income (loss) from operations
	Olefins		$	237,239			$	124,452			$	585,958			$	409,550

	Vinyls		39,554				24,059				136,123				67,724

	Corporate and other		(10,191		)		(5,994		)		(26,197		)		(18,154		)
			$	266,602			$	142,517			$	695,884			$	459,120


	Depreciation and amortization
	Olefins		$	26,515			$	27,070			$	76,415			$	74,903

	Vinyls		14,089				11,232				39,507				34,330

	Corporate and other		124				122				372				368

			$	40,728			$	38,424			$	116,294			$	109,601


	Other income (expense), net
	Olefins		$	728			$	806			$	5,889			$	2,764

	Vinyls		(742		)		146				(1,687		)		115

	Corporate and other		(273		)		270				(1,065		)		797

			$	(287	)		$	1,222			$	3,137			$	3,676


	Provision for (benefit from) income taxes
	Olefins		$	82,553			$	36,092			$	208,170			$	130,612

	Vinyls		10,710				6,556				44,120				18,989

Corporate and other		(535		)		(4,412		)		(7,643		)		(3,418		)
		$	92,728			$	38,236			$	244,647			$	146,183




		Three Months Ended September 30,								Nine Months Ended September 30,
		2013				2012				2013				2012
Capital expenditures
Olefins		$	27,577			$	46,867			$	105,656			$	92,168

Vinyls		172,565				47,001				391,864				139,836

Corporate and other		276				1,027				770				3,459

		$	200,418			$	94,895			$	498,290			$	235,463

Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes	'
	A reconciliation of total segment income from operations to consolidated income before income taxes is as follows:


			Three Months Ended September 30,								Nine Months Ended September 30,
			2013				2012				2013				2012
	Income from operations		$	266,602			$	142,517			$	695,884			$	459,120

	Interest expense		(3,297		)		(11,934		)		(14,921		)		(35,682		)
	Debt retirement costs		—				(7,082		)		—				(7,082		)

	Gain from sales of equity securities		—				477				—				16,429

	Other (expense) income, net		(287		)		1,222				3,137				3,676

	Income before income taxes		$	263,018			$	125,200			$	684,100			$	436,461

Total Assets	'


			September 30,				December 31,
			2013				2012
	Total assets
	Olefins		$	1,560,303			$	1,439,308

	Vinyls		1,577,549				1,030,912

	Corporate and other		785,597				941,976

			$	3,923,449			$	3,412,196

Goodwill_Tables

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2013
Goodwill [Abstract]	'
Schedule of Goodwill	'
	The changes in the carrying amount of goodwill for the nine months ended September 30, 2013 were as follows:


		Olefins Segment		Vinyls Segment		Total
	Balance at December 31, 2012	$	29,990	$	—	$	29,990

	Goodwill acquired during the period	—		32,026		32,026

	Balance at September 30, 2013	$	29,990	$	32,026	$	62,016

Guarantor_Disclosures_Tables

Guarantor Disclosures (Tables)	9 Months Ended
	Sep. 30, 2013
Guarantees [Abstract]	'
Condensed Consolidating Financial Information Balance Sheet	'
	Condensed Consolidating Financial Information as of September 30, 2013


			Westlake				Guarantor				Non-				Eliminations				Consolidated
			Chemical				Subsidiaries				Guarantor
			Corporation								Subsidiaries
	Balance Sheet
	Current assets
	Cash and cash equivalents		$	560,261			$	4,494			$	26,801			$	—			$	591,556

	Marketable securities		125,597				—				—				—				125,597

	Accounts receivable, net		5,373				694,473				5,489				(272,310		)		433,025

	Inventories		—				435,540				16,031				—				451,571

	Prepaid expenses and other		468				15,931				2,410				—				18,809
	current assets
	Deferred income taxes		431				21,744				118				—				22,293

	Total current assets		692,130				1,172,182				50,849				(272,310		)		1,642,851

	Property, plant and equipment, net		—				1,945,405				7,513				—				1,952,918

	Equity investments		2,635,954				98,823				31,634				(2,700,923		)		65,488

	Other assets, net		16,969				251,703				506				(6,986		)		262,192

	Total assets		$	3,345,053			$	3,468,113			$	90,502			$	(2,980,219	)		$	3,923,449

	Current liabilities
	Accounts payable		$	311,357			$	220,106			$	4,322			$	(277,718	)		$	258,067

	Accrued liabilities		15,679				151,654				1,878				5,408				174,619

	Total current liabilities		327,036				371,760				6,200				(272,310		)		432,686

	Long-term debt		752,960				10,889				—				—				763,849

	Deferred income taxes		—				416,404				748				(6,986		)		410,166

	Other liabilities		—				51,640				51				—				51,691

	Stockholders' equity		2,265,057				2,617,420				83,503				(2,700,923		)		2,265,057

	Total liabilities and		$	3,345,053			$	3,468,113			$	90,502			$	(2,980,219	)		$	3,923,449
	stockholders' equity

	Condensed Consolidating Financial Information as of December 31, 2012


			Westlake				Guarantor				Non-Guarantor				Eliminations				Consolidated
			Chemical				Subsidiaries				Subsidiaries
			Corporation
	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		389				11,386				2,925				—				14,700
current assets
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		$	3,923,466			$	3,763,382			$	90,880			$	(4,365,532	)		$	3,412,196
stockholders' equity
Condensed Consolidating Financial Information Statement Of Operations	'

	Condensed Consolidating Financial Information for the Three Months Ended September 30, 2013


			Westlake				Guarantor				Non-				Eliminations				Consolidated
			Chemical				Subsidiaries				Guarantor
			Corporation								Subsidiaries
	Statement of Operations
	Net sales		$	—			$	992,413			$	13,337			$	(1,585	)		$	1,004,165

	Cost of sales		—				689,388				11,891				(1,585		)		699,694

	Gross profit		—				303,025				1,446				—				304,471

	Selling, general and administrative		514				35,714				1,641				—				37,869
	expenses
	(Loss) income from operations		(514		)		267,311				(195		)		—				266,602

	Interest expense		(3,292		)		(5		)		—				—				(3,297		)

	Other income (expense), net		3,585				(3,821		)		(51		)		—				(287		)

	(Loss) income before income taxes		(221		)		263,485				(246		)		—				263,018

	(Benefit from) provision for income taxes		(70		)		92,849				(51		)		—				92,728

	Equity in net income of subsidiaries		170,441				—				—				(170,441		)		—

	Net income (loss)		$	170,290			$	170,636			$	(195	)		$	(170,441	)		$	170,290

	Comprehensive income		$	171,095			$	170,764			$	351			$	(171,115	)		$	171,095



	Condensed Consolidating Financial Information for the Three Months Ended September 30, 2012




			Westlake				Guarantor				Non-				Eliminations				Consolidated
			Chemical				Subsidiaries				Guarantor
			Corporation								Subsidiaries
	Statement of Operations
	Net sales		$	—			$	809,164			$	13,876			$	(1,865	)		$	821,175

	Cost of sales		—				638,892				11,969				(1,865		)		648,996

	Gross profit		—				170,272				1,907				—				172,179

	Selling, general and administrative		498				27,601				1,563				—				29,662
	expenses
	(Loss) income from operations		(498		)		142,671				344				—				142,517

	Interest expense		(11,919		)		(15		)		—				—				(11,934		)

	Debt retirement costs		(7,082		)		—				—				—				(7,082		)

	Gain from sales of equity securities		—				477				—				—				477

	Other income (expense), net		4,556				(2,744		)		(590		)		—				1,222

	(Loss) income before income taxes		(14,943		)		140,389				(246		)		—				125,200

(Benefit from) provision for income taxes		(4,498		)		42,596				138				—				38,236

Equity in net income of subsidiaries		97,409				—				—				(97,409		)		—

Net income (loss)		$	86,964			$	97,793			$	(384	)		$	(97,409	)		$	86,964

Comprehensive income		$	88,666			$	98,109			$	481			$	(98,590	)		$	88,666


Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2013


		Westlake				Guarantor				Non-				Eliminations				Consolidated
		Chemical				Subsidiaries				Guarantor
		Corporation								Subsidiaries
Statement of Operations
Net sales		$	—			$	2,777,280			$	37,561			$	(6,982	)		$	2,807,859

Cost of sales		—				1,976,131				32,943				(6,982		)		2,002,092

Gross profit		—				801,149				4,618				—				805,767

Selling, general and administrative		1,576				103,478				4,829				—				109,883
expenses
(Loss) income from operations		(1,576		)		697,671				(211		)		—				695,884

Interest expense		(14,882		)		(39		)		—				—				(14,921		)

Other income (expense), net		7,490				(2,473		)		(1,880		)		—				3,137

(Loss) income before income taxes		(8,968		)		695,159				(2,091		)		—				684,100

(Benefit from) provision for income taxes		(3,202		)		248,301				(452		)		—				244,647

Equity in net income of subsidiaries		445,219				—				—				(445,219		)		—

Net income (loss)		$	439,453			$	446,858			$	(1,639	)		$	(445,219	)		$	439,453

Comprehensive income (loss)		$	439,372			$	447,490			$	(2,483	)		$	(445,007	)		$	439,372



Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2012


		Westlake				Guarantor				Non-				Eliminations				Consolidated
		Chemical				Subsidiaries				Guarantor
		Corporation								Subsidiaries
Statement of Operations
Net sales		$	—			$	2,738,180			$	37,154			$	(5,334	)		$	2,770,000

Cost of sales		—				2,197,300				31,322				(5,334		)		2,223,288

Gross profit		—				540,880				5,832				—				546,712

Selling, general and administrative		1,500				81,288				4,804				—				87,592
expenses
(Loss) income from operations		(1,500		)		459,592				1,028				—				459,120

Interest expense		(35,652		)		(30		)		—				—				(35,682		)

Debt retirement costs		(7,082		)		—				—				—				(7,082		)

Gain from sales of equity securities		1				16,428				—				—				16,429

Other income (expense), net		12,044				(5,724		)		(2,644		)		—				3,676

(Loss) income before income taxes		(32,189		)		470,266				(1,616		)		—				436,461

(Benefit from) provision for income taxes		(11,105		)		158,228				(940		)		—				146,183

Equity in net income of subsidiaries		311,362				—				—				(311,362		)		—

Net income (loss)		$	290,278			$	312,038			$	(676	)		$	(311,362	)		$	290,278

Comprehensive income		$	291,185			$	312,017			$	252			$	(312,269	)		$	291,185

Condensed Consolidating Financial Information Statement Of Cash Flows	'
	Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2013


			Westlake				Guarantor				Non-				Eliminations				Consolidated
			Chemical				Subsidiaries				Guarantor
			Corporation								Subsidiaries
	Statement of Cash Flows
	Cash flows from operating activities
	Net income (loss)		$	439,453			$	446,858			$	(1,639	)		$	(445,219	)		$	439,453

	Adjustments to reconcile net income
	(loss) to net cash (used for) provided
	by operating activities
	Depreciation and amortization		1,094				114,432				1,861				—				117,387

	Deferred income taxes		(1,102		)		84,532				13				—				83,443

	Net changes in working capital		(458,336		)		(87,330		)		7,664				445,219				(92,783		)
	and other
	Net cash (used for) provided by		(18,891		)		558,492				7,899				—				547,500
	operating activities
	Cash flows from investing activities
	Acquisition of business		—				(178,309		)		—				—				(178,309		)

	Additions to equity investments		—				(23,338		)		—				—				(23,338		)

	Additions to property, plant and		—				(496,027		)		(2,263		)		—				(498,290		)
	equipment
	Construction of assets pending		—				(136		)		—				—				(136		)
	sale-leaseback
	Proceeds from disposition of assets		—				6				72				—				78

	Proceeds from repayment of loan		—				—				167				—				167
	to affiliate
	Proceeds from sales and maturities of		239,764				—				—				—				239,764
	securities
	Purchase of securities		(232,286		)		—				—				—				(232,286		)

	Settlements of derivative instruments		—				(2,297		)		—				—				(2,297		)

	Net cash provided by (used for)		7,478				(700,101		)		(2,024		)		—				(694,647		)
	investing activities
	Cash flows from financing activities
	Intercompany financing		(130,832		)		139,130				(8,298		)		—				—

	Dividends paid		(40,204		)		—				—				—				(40,204		)

	Proceeds from exercise of stock options		3,182				—				—				—				3,182

	Repurchase of common stock for treasury		(19,409		)		—				—				—				(19,409		)

	Windfall tax benefits from share-based		5,056				—				—				—				5,056
	payment arrangements
	Net cash (used for) provided by		(182,207		)		139,130				(8,298		)		—				(51,375		)
	financing activities
	Net decrease in cash and cash equivalents		(193,620		)		(2,479		)		(2,423		)		—				(198,522		)

	Cash and cash equivalents at beginning		753,881				6,973				29,224				—				790,078
	of period
	Cash and cash equivalents at end of period		$	560,261			$	4,494			$	26,801			$	—			$	591,556


	Condensed Consolidating Financial Information for the Nine Months Ended September 30, 2012


		Westlake				Guarantor				Non-				Eliminations				Consolidated
		Chemical				Subsidiaries				Guarantor
		Corporation								Subsidiaries
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)		$	290,278			$	312,038			$	(676	)		$	(311,362	)		$	290,278

Adjustments to reconcile net income
(loss) to net cash (used for) provided
by operating activities
Depreciation and amortization		1,149				107,191				2,410				—				110,750

Deferred income taxes		(176		)		3,932				629				—				4,385

Net changes in working capital		(317,955		)		95,909				(1,898		)		311,362				87,418
and other
Net cash (used for) provided by		(26,704		)		519,070				465				—				492,831
operating activities
Cash flows from investing activities
Additions to property, plant and		—				(234,713		)		(750		)		—				(235,463		)
equipment
Construction of assets pending		—				(5,484		)		—				—				(5,484		)
sale-leaseback
Proceeds from disposition of assets		—				414				21				—				435

Proceeds from repayment of loan		—				—				763				—				763
to affiliate
Proceeds from sales of equity securities		3				47,652				—				—				47,655

Purchase of securities		—				(2,961		)		—				—				(2,961		)

Settlements of derivative instruments		—				471				—				—				471

Net cash provided by (used for)		3				(194,621		)		34				—				(194,584		)
investing activities
Cash flows from financing activities
Intercompany financing		317,185				(321,273		)		4,088				—				—

Capitalized debt issuance costs		(2,221		)		—				—				—				(2,221		)

Dividends paid		(22,345		)		—				—				—				(22,345		)

Proceeds from borrowings		248,818				—				—				—				248,818

Proceeds from exercise of stock options		6,627				—				—				—				6,627

Repayment of borrowings		(250,000		)		—				—				—				(250,000		)

Repurchase of common stock for treasury		(10,784		)		—				—				—				(10,784		)

Utilization of restricted cash		96,433				—				—				—				96,433

Windfall tax benefits from share-based		7,792				—				—				—				7,792
payment arrangements
Net cash provided by (used for)		391,505				(321,273		)		4,088				—				74,320
financing activities
Net increase in cash and cash equivalents		364,804				3,176				4,587				—				372,567

Cash and cash equivalents at beginning		803,320				2,517				20,064				—				825,901
of period
Cash and cash equivalents at end of period		$	1,168,124			$	5,693			$	24,651			$	—			$	1,198,468

Basis_of_Financial_Statements_1

Basis of Financial Statements Basis (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Windfall tax benefits from share-based payment arrangements	$5,056	$7,792
Revision, from operating activities to financing activities	'	'
Windfall tax benefits from share-based payment arrangements	'	$7,792

Current_Marketable_Securities_1

Current Marketable Securities Marketable Securities (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]	'	'
Available-for-sale securities	$120,602	$0
Marketable Securities, Current	$125,597	$124,873

Current_Marketable_Securities_2

Current Marketable Securities Available-for-sale Securities (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	$131	'
Available-for-sale Securities, Amortized Cost Basis	120,397	'
AvailableForSaleDebtSecuritiesGrossUnrealizedGainAccumulatedInInvestments	241	'
Available ForSaleDebtSecuritiesGrossUnrealizedLossAccumulatedInInvestments	-36	'
Available-for-sale securities	120,602	0
Available-for-sale Securities, Income Tax Expense on Change in Unrealized Holding Gain (Loss)	74	'
Corporate bonds	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Available-for-sale Securities, Amortized Cost Basis	11,888	'
AvailableForSaleDebtSecuritiesGrossUnrealizedGainAccumulatedInInvestments	191	'
Available ForSaleDebtSecuritiesGrossUnrealizedLossAccumulatedInInvestments	-21	'
Available-for-sale securities	12,058	'
U.S. government debt	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Available-for-sale Securities, Amortized Cost Basis	26,400	'
AvailableForSaleDebtSecuritiesGrossUnrealizedGainAccumulatedInInvestments	23	'
Available ForSaleDebtSecuritiesGrossUnrealizedLossAccumulatedInInvestments	-6	'
Available-for-sale securities	26,417	'
Asset-backed securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Available-for-sale Securities, Amortized Cost Basis	82,109	'
AvailableForSaleDebtSecuritiesGrossUnrealizedGainAccumulatedInInvestments	27	'
Available ForSaleDebtSecuritiesGrossUnrealizedLossAccumulatedInInvestments	-9	'
Available-for-sale securities	$82,127	'

Current_Marketable_Securities_3

Current Marketable Securities Maturity Periods for Investments (Details)	9 Months Ended
	Sep. 30, 2013
Corporate bonds \| Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'1 year
Corporate bonds \| Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'5 years
US Government Agencies Debt Securities [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'1 year
Mortgage-backed securities \| Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'4 years
Mortgage-backed securities \| Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'26 years
Asset-backed securities \| Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'2 years
Asset-backed securities \| Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'5 years

Current_Marketable_Securities_4

Current Marketable Securities Held-to-maturity Securities (Details) (Short-term corporate debt securities, USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Short-term corporate debt securities	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Held-to-maturity securities	$4,995	$124,873

Accounts_Receivable_Details

Accounts Receivable (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accounts Receivable, Net [Abstract]	'	'
Trade customers	$404,678	$388,949
Affiliates	333	258
Allowance for doubtful accounts	-9,832	-11,172
Receivables from trade customers and affiliates, net	395,179	378,035
Federal and state taxes	20,421	4,011
Other	17,425	18,113
Accounts receivable, net	$433,025	$400,159

Inventories_Details

Inventories (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]	'	'
Finished products	$198,762	$200,940
Feedstock, additives and chemicals	194,558	143,912
Materials and supplies	58,251	54,446
Inventories	$451,571	$399,298

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Property, Plant and Equipment [Abstract]	'	'	'	'	'
Property, plant and equipment	$1,952,918	'	$1,952,918	'	$1,510,048
Depreciation expense on property, plant and equipment	$32,460	$30,055	$95,995	$90,615	'

Other_Assets_Additional_Inform

Other Assets (Additional Information) (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Other Assets [Abstract]	'	'	'	'
Amortization expense on intangible assets, included in other assets	$8,634	$8,717	$21,392	$20,135

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]	'	'
Long-term debt	$763,849	$763,761
3.60% Senior Notes Due 2022	'	'
Debt Instrument [Line Items]	'	'
Maturity	'2022	'
Stated interest rate	3.60%	'
Senior notes	248,960	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

LongTerm_Debt_Revolving_Credit

Long-Term Debt (Revolving Credit Facility) (Details) (Line of Credit, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Line of Credit Facility [Line Items]	'
Maximum borrowing capacity	$400,000
Percentage of commitment on borrowing availability	0.38%
Letters of credit outstanding	16,921
Remaining borrowing capacity	383,079
Minimum	'
Line of Credit Facility [Line Items]	'
Increase in credit facility borrowings	25,000
Maximum	'
Line of Credit Facility [Line Items]	'
Increase in credit facility borrowings	$150,000
Plus Libor \| Minimum	'
Line of Credit Facility [Line Items]	'
Percentage added to basis to find interest rate	1.75%
Plus Libor \| Maximum	'
Line of Credit Facility [Line Items]	'
Percentage added to basis to find interest rate	2.25%
Plus Base Rate \| Minimum	'
Line of Credit Facility [Line Items]	'
Percentage added to basis to find interest rate	0.25%
Plus Base Rate \| Maximum	'
Line of Credit Facility [Line Items]	'
Percentage added to basis to find interest rate	0.75%

StockBased_Compensation_Detail

Stock-Based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'	'	'	'
Stock-based compensation expense	$1,680	$1,515	$4,804	$4,640

Derivative_Instruments_Textual

Derivative Instruments (Textual) (Detail) (Commodity Forward Contracts, Designated As Fair Value Hedges)	Sep. 30, 2013
	gal
Commodity Forward Contracts \| Designated As Fair Value Hedges	'
Derivative [Line Items]	'
Feedstock forward contracts, in gallons	10,710,000

Derivative_Instruments_Fair_Va

Derivative Instruments (Fair Values of Derivative Instruments in Consolidated Balance Sheets) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accrued Liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative liabilities	$2,090	$13,694
Accounts Receivable	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative assets	5,749	14,427
Forward Contracts [Member] \| Accrued Liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Designated as hedging instruments, Derivative Liabilities	0	399
Not designated as hedging instruments, Derivative Liabilities	2,090	13,295
Forward Contracts [Member] \| Accounts Receivable	'	'
Derivatives, Fair Value [Line Items]	'	'
Designated as hedging instruments, Derivative Assets	3,208	13,032
Not designated as hedging instruments, Derivative Assets	$2,541	$1,395

Derivative_Instruments_Impact_

Derivative Instruments (Impact of Derivative Instruments on Income) (Details) (Cost of Sales, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 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	$236	$515	$15	($13,546)
Designated As Fair Value Hedges \| Forward Contracts [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (Loss) Recognized in Income on Derivative	-232	-515	-342	12,345
Derivatives Not Designated As Hedging Instruments \| Forward Contracts [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (Loss) Recognized in Income on Derivative	$4,854	$249	$9,897	($783)

Fair_Value_Measurements_Summar

Fair Value Measurements (Summary of Assets and Liabilities Accounted at Fair Value on Recurring Basis) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale securities	$120,602	$0
Recurring	'	'
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	-3,208	-13,032
Available-for-sale securities	120,602	'
Recurring \| 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
Available-for-sale securities	14,998	'
Recurring \| 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	-3,208	-13,032
Available-for-sale securities	105,604	'
Recurring \| Forward Contracts [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Risk management assets - Commodity forward contracts	5,749	14,427
Risk management liabilities - Commodity forward contracts	-2,090	-13,694
Recurring \| Forward Contracts [Member] \| Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Risk management assets - Commodity forward contracts	1,808	1,395
Risk management liabilities - Commodity forward contracts	-74	0
Recurring \| Forward Contracts [Member] \| Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Risk management assets - Commodity forward contracts	3,941	13,032
Risk management liabilities - Commodity forward contracts	($2,016)	($13,694)

Fair_Value_Measurements_Summar1

Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) (USD $)

3 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

3.60% Senior Notes Due 2022

6 1/2% Senior Notes Due 2029

6 3/4% Senior Notes Due 2032

2035 GO Zone 6 1/2% Notes

2035 IKE Zone 6 1/2% Notes

Loan Related To Tax-Exempt Waste Disposal Revenue Bonds Due 2027

Carrying Value

Fair Value

Carrying Value

Fair Value

Carrying Value

Fair Value

Carrying Value

Fair Value

Carrying Value

Fair Value

Carrying Value

Fair Value

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Maturity

'2022

'2029

'2032

'2035

'2027

Stated interest rate

3.60%

6.50%

6.75%

6.50%

Senior notes

$248,960

$248,872

$238,228

$251,125

$100,000

$107,800

$119,738

$250,000

$267,465

$283,168

$89,000

$94,209

$102,095

$65,000

$68,804

$74,564

Loans

$10,889

Income_Taxes_Detail

Income Taxes (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]	'	'
Effective income tax rate	35.80%	33.50%
U.S. federal statutory income tax rate	35.00%	35.00%
Anticipated reductions to unrecognized tax benefits within next twelve months	$621	'

Earnings_per_Share_Additional_

Earnings per Share (Additional Information) (Detail)	3 Months Ended		9 Months Ended
Earnings per Share (Additional Information) (Detail)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	68,662	168,362	57,759	293,062

Earnings_per_Share_Schedule_of

Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Net income	$170,290	$86,964	$439,453	$290,278
Less: Net income attributable to participating securities	-587	-452	-1,691	-1,682
Net income attributable to common shareholders	$169,703	$86,512	$437,762	$288,596

Earnings_per_Share_Reconciliat

Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	68,662	168,362	57,759	293,062
Basic	66,628,747	66,311,958	66,628,027	66,240,225
Plus incremental shares from: Assumed exercise of options	276,807	344,802	275,352	381,295
Weighted average common shares-diluted	66,905,554	66,656,760	66,903,379	66,621,520
Earnings per share: Basic	$2.55	$1.30	$6.57	$4.36
Earnings per share: Diluted	$2.54	$1.30	$6.54	$4.33

Pension_and_PostRetirement_Ben2

Pension and Post-Retirement Benefit Costs (Components of Net Periodic Benefit Cost) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	$275	$250	$815	$754
Interest cost	515	645	1,531	1,936
Expected return on plan assets	-713	-623	-2,140	-1,867
Amortization of prior service cost	74	74	223	223
Amortization of net loss	510	445	1,449	1,329
Net periodic benefit cost	661	791	1,878	2,375
Post-Retirement Healthcare	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	2	2	7	7
Interest cost	147	185	442	555
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	21	21	63	63
Amortization of net loss	90	44	269	132
Net periodic benefit cost	$260	$252	$781	$757

Pension_and_PostRetirement_Ben3

Pension and Post-Retirement Benefit Costs (Additional Information) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Defined Benefit Plan Disclosure [Line Items]	'	'
Document Fiscal Year Focus	'2013	'
Salaried Pension Plan	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Employer contribution	$776	$2,283
Expected additional contributions	388	'
Wage Pension Plan	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Employer contribution	640	1,542
Expected additional contributions	$290	'

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income Changes in AOCI (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Accumulated other comprehensive income (loss), beginning balance	($10,840)
Other comprehensive loss before reclassifications	-1,314
Amounts reclassified from accumulated other comprehensive loss	1,233
Net other comprehensive income (loss) for the period	-81
Accumulated other comprehensive income (loss), ending balance	-10,921
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	-601
Amounts reclassified from accumulated other comprehensive loss	1,233
Net other comprehensive income (loss) for the period	632
Accumulated other comprehensive income (loss), ending balance	-15,719
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	-844
Amounts reclassified from accumulated other comprehensive loss	0
Net other comprehensive income (loss) for the period	-844
Accumulated other comprehensive income (loss), ending balance	4,667
Net Unrealized Holding Gains on Investmetnts, Net of Tax	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Accumulated other comprehensive income (loss), beginning balance	0
Other comprehensive loss before reclassifications	131
Amounts reclassified from accumulated other comprehensive loss	0
Net other comprehensive income (loss) for the period	131
Accumulated other comprehensive income (loss), ending balance	$131

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income Reclassifications in AOCI (Details) (USD $)	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'
Income before income taxes	$263,018		$125,200	$684,100		$436,461
Provision for income taxes	-92,728		-38,236	-244,647		-146,183
Net income	170,290		86,964	439,453		290,278
Accumulated Defined Benefit Plans Adjustment \| Reclassification out of Accumulated Other Comprehensive Income	'		'	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'
Prior service costs	-95	[1]	'	-286	[1]	'
Net loss	-600	[1]	'	-1,718	[1]	'
Income before income taxes	-695		'	-2,004		'
Provision for income taxes	267		'	771		'
Net income	($428)		'	($1,233)		'

[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.

Acquisitions_Narrative_Details

Acquisitions (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	1-May-13	Sep. 30, 2013
					Pipe and Foundation Group	Pipe and Foundation Group
					lb
Business Acquisition [Line Items]	'	'	'	'	'	'
Annual production capacity of PVC pipe and fittings	'	'	'	'	150,000,000	'
Cash paid for purchase	'	'	$178,309	$0	$178,309	'
Net sales	1,004,165	821,175	2,807,859	2,770,000	'	'
Net income	170,290	86,964	439,453	290,278	'	'
Acquisition-related costs	'	'	'	'	'	$1,124

Acquisitions_Assets_Acquired_a

Acquisitions (Assets Acquired and Liabilities Assumed) (Details) (USD $)

9 Months Ended

0 Months Ended

2 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

1-May-13

Jun. 30, 2013

1-May-13

Jun. 30, 2013

1-May-13

Jun. 30, 2013

1-May-13

Pipe and Foundation Group

Trademarks

Customer relationships

Developed technology

Other intangibles

Fair value of consideration transferred:

Cash

$178,309

Preliminary allocation of consideration transferred to net assets acquired:

Accounts receivable

17,695

[1]

Inventories

25,948

Property, plant and equipment

31,261

Intangible assets:

Intangible assets

5,200

57,600

18,900

300

Current liabilities

-10,595

Other liabilities

-26

Total identifiable net assets

146,283

Goodwill

62,016

29,990

32,026

[2]

Consideration transferred

178,309

Fair value of accounts receivable acquired

17,695

Gross contractual amount of acquired receivables

17,772

Amount of acquired receivables expected to be uncollectible

Weighted average life

'15 years

'2 years

[1]

The fair value of accounts receivable acquired is $17,695, with the gross contractual amount being $17,772. The Company expects $77 to be uncollectible.

[2]

The goodwill recognized is primarily attributable to synergies from the Company's vinyls integration strategy expected to arise from the Company's PFG acquisition, as well as intangible assets that do not qualify for separate recognition. The goodwill is expected to be deductible for income tax purposes. The Company has not yet completed the process of assigning the goodwill to its reporting units.

Acquisitions_Supplemental_Nonc

Acquisitions (Supplemental Noncash Investing Cash Flow Information) (Details) (USD $)	9 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	1-May-13
	Sep. 30, 2013	Sep. 30, 2012	Pipe and Foundation Group
Business Acquisition [Line Items]	'	'	'
Fair value of assets acquired	'	'	$188,930
Acquisition of business	-178,309	0	-178,309
Liabilities assumed	'	'	$10,621

Commitments_and_Contingencies_

Commitments and Contingencies (Additional Information) (Detail) (USD $)	0 Months Ended	1 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 17, 2010	Dec. 31, 2007	Dec. 31, 2007	Dec. 31, 2012
	Mar. 17, 2010	Dec. 31, 2007	Polyone	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

Segment_Information_Additional

Segment Information (Additional Information) (Detail)	3 Months Ended
	Sep. 30, 2013
	Segment
Segment Reporting [Abstract]	'
Number of segments	2

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	$1,004,165	$821,175	$2,807,859	$2,770,000
Income (loss) from operations	266,602	142,517	695,884	459,120
Depreciation and amortization	40,728	38,424	116,294	109,601
Other (expense) income, net	-287	1,222	3,137	3,676
Provision for (benefit from) income taxes	92,728	38,236	244,647	146,183
Capital expenditures	200,418	94,895	498,290	235,463
Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	679,339	539,785	1,885,525	1,944,775
Income (loss) from operations	237,239	124,452	585,958	409,550
Depreciation and amortization	26,515	27,070	76,415	74,903
Other (expense) income, net	728	806	5,889	2,764
Provision for (benefit from) income taxes	82,553	36,092	208,170	130,612
Capital expenditures	27,577	46,867	105,656	92,168
Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	324,826	281,390	922,334	825,225
Income (loss) from operations	39,554	24,059	136,123	67,724
Depreciation and amortization	14,089	11,232	39,507	34,330
Other (expense) income, net	-742	146	-1,687	115
Provision for (benefit from) income taxes	10,710	6,556	44,120	18,989
Capital expenditures	172,565	47,001	391,864	139,836
Corporate and Other	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Income (loss) from operations	-10,191	-5,994	-26,197	-18,154
Depreciation and amortization	124	122	372	368
Other (expense) income, net	-273	270	-1,065	797
Provision for (benefit from) income taxes	-535	-4,412	-7,643	-3,418
Capital expenditures	276	1,027	770	3,459
Polyethylene \| Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	460,105	431,614	1,294,566	1,275,057
Ethylene, Styrene And Other \| Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	219,234	108,171	590,959	669,718
PVC, Caustic Soda And Other \| Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	212,041	191,310	612,391	569,316
Building Products \| Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	112,785	90,080	309,943	255,909
Intersegment sales	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	85,857	77,162	231,718	248,838
Intersegment sales \| Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	85,454	76,771	230,607	247,671
Intersegment sales \| Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	$403	$391	$1,111	$1,167

Segment_Information_Reconcilia

Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting [Abstract]	'	'	'	'
Income from operations	$266,602	$142,517	$695,884	$459,120
Interest expense	-3,297	-11,934	-14,921	-35,682
Debt retirement costs	0	-7,082	0	-7,082
Gain from sales of equity securities	0	477	0	16,429
Other (expense) income, net	-287	1,222	3,137	3,676
Income before income taxes	$263,018	$125,200	$684,100	$436,461

Segment_Information_Total_Asse

Segment Information (Total Assets) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	$3,923,449	$3,412,196
Olefins	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	1,560,303	1,439,308
Vinyls	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	1,577,549	1,030,912
Corporate and Other	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	$785,597	$941,976

Goodwill_Details

Goodwill (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Goodwill [Line Items]	'	'
Goodwill	$62,016	$29,990
Goodwill, Acquired During Period	32,026	'
Olefins	'	'
Goodwill [Line Items]	'	'
Goodwill	29,990	29,990
Goodwill, Acquired During Period	0	'
Vinyls	'	'
Goodwill [Line Items]	'	'
Goodwill	32,026	0
Goodwill, Acquired During Period	$32,026	'

Guarantor_Disclosures_Addition

Guarantor Disclosures (Additional Information) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 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

Guarantor_Disclosures_Condense

Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	$591,556	$790,078	$1,198,468	$825,901
Marketable Securities, Current	125,597	124,873	'	'
Accounts receivable, net	433,025	400,159	'	'
Inventories	451,571	399,298	'	'
Prepaid expenses and other current assets	18,809	14,700	'	'
Deferred income taxes	22,293	22,305	'	'
Total current assets	1,642,851	1,751,413	'	'
Property, plant and equipment, net	1,952,918	1,510,048	'	'
Equity investments	65,488	43,736	'	'
Other assets, net	262,192	106,999	'	'
Total assets	3,923,449	3,412,196	'	'
Accounts payable	258,067	217,050	'	'
Accrued liabilities	174,619	181,460	'	'
Total current liabilities	432,686	398,510	'	'
Long-term debt	763,849	763,761	'	'
Deferred income taxes	410,166	326,290	'	'
Other liabilities	51,691	51,379	'	'
Stockholders' equity	2,265,057	1,872,256	'	'
Total liabilities and stockholders' equity	3,923,449	3,412,196	'	'
Westlake Chemical Corporation	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	560,261	753,881	1,168,124	803,320
Marketable Securities, Current	125,597	124,873	'	'
Accounts receivable, net	5,373	7,933	'	'
Inventories	0	0	'	'
Prepaid expenses and other current assets	468	389	'	'
Deferred income taxes	431	431	'	'
Total current assets	692,130	887,507	'	'
Property, plant and equipment, net	0	0	'	'
Equity investments	2,635,954	3,018,926	'	'
Other assets, net	16,969	17,033	'	'
Total assets	3,345,053	3,923,466	'	'
Accounts payable	311,357	1,285,530	'	'
Accrued liabilities	15,679	12,808	'	'
Total current liabilities	327,036	1,298,338	'	'
Long-term debt	752,960	752,872	'	'
Deferred income taxes	0	0	'	'
Other liabilities	0	0	'	'
Stockholders' equity	2,265,057	1,872,256	'	'
Total liabilities and stockholders' equity	3,345,053	3,923,466	'	'
Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	4,494	6,973	5,693	2,517
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	694,473	1,675,274	'	'
Inventories	435,540	385,140	'	'
Prepaid expenses and other current assets	15,931	11,386	'	'
Deferred income taxes	21,744	21,581	'	'
Total current assets	1,172,182	2,100,354	'	'
Property, plant and equipment, net	1,945,405	1,502,902	'	'
Equity investments	98,823	65,448	'	'
Other assets, net	251,703	94,678	'	'
Total assets	3,468,113	3,763,382	'	'
Accounts payable	220,106	192,443	'	'
Accrued liabilities	151,654	178,915	'	'
Total current liabilities	371,760	371,358	'	'
Long-term debt	10,889	10,889	'	'
Deferred income taxes	416,404	331,320	'	'
Other liabilities	51,640	51,312	'	'
Stockholders' equity	2,617,420	2,998,503	'	'
Total liabilities and stockholders' equity	3,468,113	3,763,382	'	'
Non-Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	26,801	29,224	24,651	20,064
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	5,489	2,959	'	'
Inventories	16,031	14,158	'	'
Prepaid expenses and other current assets	2,410	2,925	'	'
Deferred income taxes	118	293	'	'
Total current assets	50,849	49,559	'	'
Property, plant and equipment, net	7,513	7,146	'	'
Equity investments	31,634	32,923	'	'
Other assets, net	506	1,252	'	'
Total assets	90,502	90,880	'	'
Accounts payable	4,322	13,969	'	'
Accrued liabilities	1,878	852	'	'
Total current liabilities	6,200	14,821	'	'
Long-term debt	0	0	'	'
Deferred income taxes	748	934	'	'
Other liabilities	51	67	'	'
Stockholders' equity	83,503	75,058	'	'
Total liabilities and stockholders' equity	90,502	90,880	'	'
Eliminations	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	0	0	0	0
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	-272,310	-1,286,007	'	'
Inventories	0	0	'	'
Prepaid expenses and other current assets	0	0	'	'
Deferred income taxes	0	0	'	'
Total current assets	-272,310	-1,286,007	'	'
Property, plant and equipment, net	0	0	'	'
Equity investments	-2,700,923	-3,073,561	'	'
Other assets, net	-6,986	-5,964	'	'
Total assets	-2,980,219	-4,365,532	'	'
Accounts payable	-277,718	-1,274,892	'	'
Accrued liabilities	5,408	-11,115	'	'
Total current liabilities	-272,310	-1,286,007	'	'
Long-term debt	0	0	'	'
Deferred income taxes	-6,986	-5,964	'	'
Other liabilities	0	0	'	'
Stockholders' equity	-2,700,923	-3,073,561	'	'
Total liabilities and stockholders' equity	($2,980,219)	($4,365,532)	'	'

Guarantor_Disclosures_Condense1

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	$1,004,165	$821,175	$2,807,859	$2,770,000
Cost of sales	699,694	648,996	2,002,092	2,223,288
Gross profit	304,471	172,179	805,767	546,712
Selling, general and administrative expenses	37,869	29,662	109,883	87,592
Income from operations	266,602	142,517	695,884	459,120
Interest expense	-3,297	-11,934	-14,921	-35,682
Debt retirement costs	0	-7,082	0	-7,082
Gain from sales of equity securities	0	477	0	16,429
Other income (expense), net	-287	1,222	3,137	3,676
Income before income taxes	263,018	125,200	684,100	436,461
Provision for (benefit from) income taxes	92,728	38,236	244,647	146,183
Equity in net income of subsidiaries	0	0	0	0
Net income	170,290	86,964	439,453	290,278
Comprehensive income (loss)	171,095	88,666	439,372	291,185
Westlake Chemical Corporation	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	514	498	1,576	1,500
Income from operations	-514	-498	-1,576	-1,500
Interest expense	-3,292	-11,919	-14,882	-35,652
Debt retirement costs	'	-7,082	'	-7,082
Gain from sales of equity securities	'	0	'	1
Other income (expense), net	3,585	4,556	7,490	12,044
Income before income taxes	-221	-14,943	-8,968	-32,189
Provision for (benefit from) income taxes	-70	-4,498	-3,202	-11,105
Equity in net income of subsidiaries	170,441	97,409	445,219	311,362
Net income	170,290	86,964	439,453	290,278
Comprehensive income (loss)	171,095	88,666	439,372	291,185
Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	992,413	809,164	2,777,280	2,738,180
Cost of sales	689,388	638,892	1,976,131	2,197,300
Gross profit	303,025	170,272	801,149	540,880
Selling, general and administrative expenses	35,714	27,601	103,478	81,288
Income from operations	267,311	142,671	697,671	459,592
Interest expense	-5	-15	-39	-30
Debt retirement costs	'	0	'	0
Gain from sales of equity securities	'	477	'	16,428
Other income (expense), net	-3,821	-2,744	-2,473	-5,724
Income before income taxes	263,485	140,389	695,159	470,266
Provision for (benefit from) income taxes	92,849	42,596	248,301	158,228
Equity in net income of subsidiaries	0	0	0	0
Net income	170,636	97,793	446,858	312,038
Comprehensive income (loss)	170,764	98,109	447,490	312,017
Non-Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	13,337	13,876	37,561	37,154
Cost of sales	11,891	11,969	32,943	31,322
Gross profit	1,446	1,907	4,618	5,832
Selling, general and administrative expenses	1,641	1,563	4,829	4,804
Income from operations	-195	344	-211	1,028
Interest expense	0	0	0	0
Debt retirement costs	'	0	'	0
Gain from sales of equity securities	'	0	'	0
Other income (expense), net	-51	-590	-1,880	-2,644
Income before income taxes	-246	-246	-2,091	-1,616
Provision for (benefit from) income taxes	-51	138	-452	-940
Equity in net income of subsidiaries	0	0	0	0
Net income	-195	-384	-1,639	-676
Comprehensive income (loss)	351	481	-2,483	252
Eliminations	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	-1,585	-1,865	-6,982	-5,334
Cost of sales	-1,585	-1,865	-6,982	-5,334
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Income from operations	0	0	0	0
Interest expense	0	0	0	0
Debt retirement costs	'	0	'	0
Gain from sales of equity securities	'	0	'	0
Other income (expense), net	0	0	0	0
Income before income taxes	0	0	0	0
Provision for (benefit from) income taxes	0	0	0	0
Equity in net income of subsidiaries	-170,441	-97,409	-445,219	-311,362
Net income	-170,441	-97,409	-445,219	-311,362
Comprehensive income (loss)	($171,115)	($98,590)	($445,007)	($312,269)

Guarantor_Disclosures_Condense2

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	$439,453	$290,278
Depreciation and amortization	117,387	110,750
Deferred income taxes	83,443	4,385
Net changes in working capital and other	-92,783	87,418
Net cash provided by operating activities	547,500	492,831
Acquisition of business	-178,309	0
Additions to equity investments	-23,338	0
Additions to property, plant and equipment	-498,290	-235,463
Construction of assets pending sale-leaseback	-136	-5,484
Proceeds from disposition of assets	78	435
Proceeds from repayment of loan to affiliate	167	763
Proceeds from sales of equity securities	239,764	47,655
Purchase of securities and other investments	-232,286	-2,961
Settlements of derivative instruments	-2,297	471
Net cash used for investing activities	-694,647	-194,584
Intercompany financing	0	0
Capitalized debt issuance costs	0	-2,221
Dividends paid	-40,204	-22,345
Proceeds from Issuance of Long-term Debt	0	248,818
Proceeds from exercise of stock options	3,182	6,627
Repayments of Long-term Debt	0	-250,000
Repurchase of common stock for treasury	-19,409	-10,784
Utilization of restricted cash	0	96,433
Windfall tax benefits from share-based payment arrangements	5,056	7,792
Net cash provided by financing activities	-51,375	74,320
Net increase in cash and cash equivalents	-198,522	372,567
Cash and cash equivalents at beginning of period	790,078	825,901
Cash and cash equivalents at end of period	591,556	1,198,468
Westlake Chemical Corporation	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	439,453	290,278
Depreciation and amortization	1,094	1,149
Deferred income taxes	-1,102	-176
Net changes in working capital and other	-458,336	-317,955
Net cash provided by operating activities	-18,891	-26,704
Acquisition of business	0	'
Additions to equity investments	0	'
Additions to property, plant and equipment	0	0
Construction of assets pending sale-leaseback	0	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities	239,764	3
Purchase of securities and other investments	-232,286	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	7,478	3
Intercompany financing	-130,832	317,185
Capitalized debt issuance costs	'	-2,221
Dividends paid	-40,204	-22,345
Proceeds from Issuance of Long-term Debt	'	248,818
Proceeds from exercise of stock options	3,182	6,627
Repayments of Long-term Debt	'	-250,000
Repurchase of common stock for treasury	-19,409	-10,784
Utilization of restricted cash	'	96,433
Windfall tax benefits from share-based payment arrangements	5,056	7,792
Net cash provided by financing activities	-182,207	391,505
Net increase in cash and cash equivalents	-193,620	364,804
Cash and cash equivalents at beginning of period	753,881	803,320
Cash and cash equivalents at end of period	560,261	1,168,124
Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	446,858	312,038
Depreciation and amortization	114,432	107,191
Deferred income taxes	84,532	3,932
Net changes in working capital and other	-87,330	95,909
Net cash provided by operating activities	558,492	519,070
Acquisition of business	-178,309	'
Additions to equity investments	-23,338	'
Additions to property, plant and equipment	-496,027	-234,713
Construction of assets pending sale-leaseback	-136	-5,484
Proceeds from disposition of assets	6	414
Proceeds from repayment of loan to affiliate	0	0
Proceeds from sales of equity securities	0	47,652
Purchase of securities and other investments	0	-2,961
Settlements of derivative instruments	-2,297	471
Net cash used for investing activities	-700,101	-194,621
Intercompany financing	139,130	-321,273
Capitalized debt issuance costs	'	0
Dividends paid	0	0
Proceeds from Issuance of Long-term Debt	'	0
Proceeds from exercise of stock options	0	0
Repayments of Long-term Debt	'	0
Repurchase of common stock for treasury	0	0
Utilization of restricted cash	'	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	139,130	-321,273
Net increase in cash and cash equivalents	-2,479	3,176
Cash and cash equivalents at beginning of period	6,973	2,517
Cash and cash equivalents at end of period	4,494	5,693
Non-Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	-1,639	-676
Depreciation and amortization	1,861	2,410
Deferred income taxes	13	629
Net changes in working capital and other	7,664	-1,898
Net cash provided by operating activities	7,899	465
Acquisition of business	0	'
Additions to equity investments	0	'
Additions to property, plant and equipment	-2,263	-750
Construction of assets pending sale-leaseback	0	0
Proceeds from disposition of assets	72	21
Proceeds from repayment of loan to affiliate	167	763
Proceeds from sales of equity securities	0	0
Purchase of securities and other investments	0	0
Settlements of derivative instruments	0	0
Net cash used for investing activities	-2,024	34
Intercompany financing	-8,298	4,088
Capitalized debt issuance costs	'	0
Dividends paid	0	0
Proceeds from Issuance of Long-term Debt	'	0
Proceeds from exercise of stock options	0	0
Repurchase of common stock for treasury	0	0
Utilization of restricted cash	'	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	-8,298	4,088
Net increase in cash and cash equivalents	-2,423	4,587
Cash and cash equivalents at beginning of period	29,224	20,064
Cash and cash equivalents at end of period	26,801	24,651
Eliminations	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	-445,219	-311,362
Depreciation and amortization	0	0
Deferred income taxes	0	0
Net changes in working capital and other	445,219	311,362
Net cash provided by operating activities	0	0
Acquisition of business	0	'
Additions to equity investments	0	'
Additions to property, plant and equipment	0	0
Construction of assets pending sale-leaseback	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	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	0
Capitalized debt issuance costs	'	0
Dividends paid	0	0
Proceeds from Issuance of Long-term Debt	'	0
Proceeds from exercise of stock options	0	0
Repayments of Long-term Debt	'	0
Repurchase of common stock for treasury	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
Cash and cash equivalents at end of period	$0	$0