Westlake (WLK) 10-Q 6 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 29, 2014
Document Documentand Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'WLK	'
Entity Registrant Name	'WESTLAKE CHEMICAL CORP	'
Entity Central Index Key	'0001262823	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	133,429,082

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$532,643	$461,301
Marketable Securities, Current	243,694	239,388
Accounts receivable, net	421,879	428,457
Inventories	439,009	471,879
Prepaid expenses and other current assets	15,880	13,888
Deferred income taxes	34,158	34,169
Total current assets	1,687,263	1,649,082
Property, plant and equipment, net	2,150,643	2,088,014
Equity investments	67,560	66,875
Other assets, net	'	'
Intangible assets, net	157,086	159,046
Deferred charges and other assets	109,404	97,892
Total other assets, net	266,490	256,938
Total assets	4,171,956	4,060,909
Current liabilities	'	'
Accounts payable	211,952	249,613
Accrued liabilities	147,982	155,245
Total current liabilities	359,934	404,858
Long-term debt	763,909	763,879
Deferred income taxes	447,203	437,976
Other liabilities	32,338	35,593
Total liabilities	1,603,384	1,642,306
Commitments and contingencies (Notes 7 and 15)	'	'
Stockholders' equity	'	'
Preferred stock, $0.01 par value, 50,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.01 par value, 150,000,000 shares authorized; 134,682,004 and 134,580,208 shares issued at March 31, 2014 and December 31, 2013, respectively (Note 1)	1,347	1,346
Common stock, held in treasury, at cost; 1,252,922 shares at March 31, 2014 and December 31, 2013 (Note 1)	-46,220	-46,220
Additional paid-in capital	519,323	511,432
Retained earnings	2,095,904	1,954,661
Accumulated other comprehensive loss	-1,782	-2,616
Total stockholders' equity	2,568,572	2,418,603
Total liabilities and stockholders' equity	$4,171,956	$4,060,909

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
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	134,682,004	134,580,208
Common stock, held in treasury	1,252,922	1,252,922

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Income Statement [Abstract]	'		'
Net sales	$1,027,676		$864,647
Cost of sales	740,666		636,838
Gross profit	287,010		227,809
Selling, general and administrative expenses	38,955		33,754
Income from operations	248,055		194,055
Other income (expense)	'		'
Interest expense	-9,157		-6,281
Other (expense) income, net	2,509		3,519
Income before income taxes	241,407		191,293
Provision for income taxes	83,375		67,946
Net income	$158,032		$123,347
Earnings per share:	'		'
Basic	$1.18	[1]	$0.92	[1]
Diluted	$1.18	[1]	$0.92	[1]
Weighted average shares outstanding:	'		'
Basic	133,072,254	[1]	133,251,071	[1]
Diluted	133,612,924	[1]	133,817,737	[1]
Dividends per common share	$0.13		$0.09
[1]	Share amounts and per share data for the three months ended March 31, 2013 have been restated to reflect the effect of a two-for-one stock split on MarchB 18, 2014. See Note 1 for additional information.

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net income	$158,032	$123,347
Pension and other post-retirement benefits liability	'	'
Amortization of benefits liability	219	614
Income tax provision on pension and other post-retirement benefits liability	-84	-236
Foreign currency translation adjustments	-898	-570
Available-for-sale investments	'	'
Unrealized holding gains (losses) on investments	2,467	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	-25	0
Other Comprehensive Income (Loss) Income Tax (Provision) Benefit On Available For Sale Investment	895	0
Other comprehensive income (loss)	834	-192
Comprehensive income	$158,866	$123,155

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities	'	'
Net income	$158,032	$123,347
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	45,972	35,356
Provision for (recovery of) doubtful accounts	-144	393
Amortization of debt issuance costs	365	365
Stock-based compensation expense	2,222	1,499
Loss from disposition of fixed assets	855	2,387
Deferred income taxes	8,275	29,466
Windfall tax benefits from share-based payment arrangements	-3,512	-3,844
Equity in (income) loss of joint ventures	-685	-178
Other Operating Activities, Cash Flow Statement	444	0
Changes in operating assets and liabilities	'	'
Accounts receivable	5,332	-7,917
Inventories	32,870	-8,776
Prepaid expenses and other current assets	-1,478	-2,077
Accounts payable	-29,706	14,733
Accrued liabilities	-4,952	-14,670
Other, net	-1,385	-53,832
Net cash provided by operating activities	212,505	116,252
Cash flows from investing activities	'	'
Additions to property, plant and equipment	-110,741	-150,784
Proceeds from disposition of assets	12	2
Proceeds from repayment of loan to affiliate	0	167
Proceeds from sale and maturities of securities	30,119	124,873
Purchase of securities and other investments	-49,025	-94,903
Settlements of derivative instruments	-409	-679
Net cash used for investing activities	-130,044	-121,324
Cash flows from financing activities	'	'
Dividends paid	-16,789	-12,553
Proceeds from exercise of stock options	2,158	1,590
Windfall tax benefits from share-based payment arrangements	3,512	3,844
Net cash provided by financing activities	-11,119	-7,119
Net increase in cash and cash equivalents	71,342	-12,191
Cash and cash equivalents at beginning of period	461,301	790,078
Cash and cash equivalents at end of period	$532,643	$777,887

Basis_of_Financial_Statements

Basis of Financial Statements	3 Months Ended
	Mar. 31, 2014
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, 2013 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, 2013 (the "2013 Form 10-K"), filed with the SEC on February 21, 2014. 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, 2013.
	In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of March 31, 2014, its results of operations for the three months ended March 31, 2014 and 2013 and the changes in its cash position for the three months ended March 31, 2014 and 2013.
	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, 2014 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.
	On February 14, 2014, the Company's Board of Directors authorized a two-for-one split of the Company's common stock. Stockholders of record as of February 28, 2014 were entitled to one additional share for every share outstanding, which was distributed on March 18, 2014. The total number of authorized common stock shares and associated par value were unchanged by this stock split. All share amounts and per share data included in the accompanying consolidated financial statements and related notes have been restated to reflect the effect of the stock split.
	Recent Accounting Pronouncements
	There are no recently issued accounting standards which are expected to impact the Company's consolidated financial position, results of operations or cash flows.

Financial_Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]	'
Financial Instruments	'
	Financial Instruments
	Cash Equivalents
	The Company had $411,527 and $263,967 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at March 31, 2014 and December 31, 2013, respectively. The Company's investments in held-to-maturity securities are held at amortized cost, which approximates fair value.
	Available-for-Sale Marketable Securities
	Investments in available-for-sale securities were classified as follows:
		March 31,				December 31,
		2014				2013
	Current	$	243,694			$	239,388
	Non-current	17,195				—
	Total available-for-sale securities	$	260,889			$	239,388
	The cost, gross unrealized gains, gross unrealized losses and fair value of the Company’s available-for-sale securities were as follows:
			March 31, 2014
			Cost				Gross		Gross			Fair Value
							Unrealized		Unrealized
							Gains		Losses (1)
	Debt securities
	Corporate bonds		$	116,669			$	470	$	(41	)	$	117,098
	U.S. government debt (2)		102,201				133		(46		)	102,288
	Asset-backed securities		24,268				47		(7		)	24,308
	Equity securities		14,985				2,210		—			17,195
	Total available-for-sale securities		$	258,123			$	2,860	$	(94	)	$	260,889
			December 31, 2013
			Cost				Gross		Gross			Fair Value
							Unrealized		Unrealized
							Gains		Losses (1)
	Debt securities
	Corporate bonds		$	108,300			$	340	$	(69	)	$	108,571
	U.S. government debt (2)		106,335				60		(79		)	106,316
	Asset-backed securities		24,478				34		(11		)	24,501
	Total available-for-sale securities		$	239,113			$	434	$	(159	)	$	239,388
	_____________
	-1	All unrealized loss positions were held at a loss for less than 12 months.
	-2	U.S. Treasury obligations, U.S. government agency obligations and U.S government agency mortgage-backed securities.
	As of March 31, 2014 and December 31, 2013, net unrealized gains on the Company's available-for-sale securities of $1,773 and $176, respectively, net of income tax expense of $993 and $99, respectively, 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 March 31, 2014, the corporate bond securities held by the Company had maturities between one month to five years; U.S. government debt securities, excluding U.S. government agency mortgage-backed securities, had maturities between one month to four years; U.S. government agency mortgage-backed securities had maturities between one to 29 years; and asset-backed securities had maturities between one to six years.
	The proceeds from sales and maturities of available-for-sale securities and the gross realized gains and losses included in the consolidated statement of operations are reflected in the table below. The cost of securities sold was determined using the specific identification method. There were no sales or maturities of available-for-sale securities during the three months ended March 31, 2013.
			Three Months Ended March 31,
			2014
	Proceeds from sales and maturities of securities		$	30,119
	Gross realized gains		13
	Gross realized losses		(38		)

Accounts_Receivable

Accounts Receivable	3 Months Ended
	Mar. 31, 2014
Accounts Receivable, Net [Abstract]	'
Accounts Receivable	'
	Accounts Receivable
	Accounts receivable consist of the following:
		March 31,			December 31,
		2014			2013
	Trade customers	$	415,812		$	410,302
	Affiliates	287			315
	Allowance for doubtful accounts	(11,592		)	(11,741		)
		404,507			398,876
	Federal and state taxes	5,248			20,820
	Other	12,124			8,761
	Accounts receivable, net	$	421,879		$	428,457

Inventories

Inventories	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories consist of the following:
		March 31,		December 31,
		2014		2013
	Finished products	$	240,339	$	232,658
	Feedstock, additives and chemicals	139,189		180,646
	Materials and supplies	59,481		58,575
	Inventories	$	439,009	$	471,879

Property_Plant_and_Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2014
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment	'
	Property, Plant and Equipment
	As of March 31, 2014, the Company had property, plant and equipment, net totaling $2,150,643. 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 $38,061 and $30,920 is included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2014 and 2013, respectively.

Other_Assets

Other Assets	3 Months Ended
	Mar. 31, 2014
Other Assets [Abstract]	'
Other Assets	'
	Other Assets
	Goodwill for the Olefins segment was $29,990 at March 31, 2014 and December 31, 2013. Goodwill for the Vinyls segment was $32,026 at March 31, 2014 and December 31, 2013. There were no changes in the carrying amount of goodwill by operating segments for the three months ended March 31, 2014.
	Amortization expense on intangible and other assets of $8,276 and $4,801 is included in the consolidated statements of operations for the three months ended March 31, 2014 and 2013, respectively.

LongTerm_Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	Long-Term Debt
	Long-term debt consists of the following:
		March 31,		December 31,
		2014		2013
	3.60% senior notes due 2022	$	249,020	$	248,990
	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	$	763,909	$	763,879
	Revolving Credit Facility
	The Company has a $400,000 senior secured revolving credit facility. The facility includes a provision permitting the Company to increase the size of the facility, up to four times, in increments of at least $25,000 each (up to a maximum of $150,000) under certain circumstances if lenders agree to commit to such an increase. At March 31, 2014, the Company had no borrowings outstanding under the revolving credit facility. Any borrowings under the facility will bear interest at either LIBOR plus a spread ranging from 1.75% to 2.25% or a base rate plus a spread ranging from 0.25% to 0.75%. The revolving credit facility also requires an unused commitment fee of 0.375% per annum. All interest rates under the facility are subject to monthly grid pricing adjustments based on prior month average daily loan availability. The revolving credit facility matures on September 16, 2016. As of March 31, 2014, 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	3 Months Ended
	Mar. 31, 2014
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 $2,222 and $1,499 for the three months ended March 31, 2014 and 2013, respectively.

Derivative_Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2014
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 statement of operations for the three months ended March 31, 2013. The Company had no derivative instruments that were designated as fair value hedges for the three months ended March 31, 2014.
	Gains and losses from changes in the fair value of derivative instruments that are not designated as hedging instruments were included in gross profit in the consolidated statements of operations for the three months ended March 31, 2014 and 2013.
	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 March 31, 2014 and December 31, 2013.
	The fair values of derivative instruments in the Company's consolidated balance sheets were as follows:
		Derivative Assets
		Balance Sheet Location	Fair Value as of
			March 31,			December 31,
			2014			2013
	Not designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	$	248		$	296
	Total derivative assets		$	248		$	296
		Derivative Liabilities
		Balance Sheet Location	Fair Value as of
			March 31,			December 31,
			2014			2013
	Not designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	$	54		$	176
	Total derivative liabilities		$	54		$	176
	The following tables reflect the impact of derivative instruments designated as fair value hedges and the related hedged item on the Company's consolidated statements of operations. For the three months ended March 31, 2013, 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 March 31,
	Hedging Relationships	Recognized in
		Income on Derivative	2014			2013
	Commodity forward contracts	Cost of sales	$	—		$	(1,643	)
	Hedged Items in Fair Value	Location of Gain (Loss)	Three Months Ended March 31,
	Hedging Relationships	Recognized in
		Income on Hedged Items	2014			2013
	Firm commitment designated as the hedged item	Cost of sales	$	—		$	1,395
	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 March 31,
	Hedging Instruments	Recognized in
		Income on Derivative	2014			2013
	Commodity forward contracts	Gross profit	$	(611	)	$	7,335
	See Note 10 for the fair value of the Company's derivative instruments.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
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:
		31-Mar-14
		Level 1		Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	—	$	248		$	248
	Risk management liabilities - Commodity forward contracts	—		(54		)	(54		)
	Available-for-sale marketable securities	100,603		160,286			260,889
		December 31, 2013
		Level 1		Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	48	$	248		$	296
	Risk management liabilities - Commodity forward contracts	—		(176		)	(176		)
	Available-for-sale marketable securities	91,595		147,793			239,388
	The Level 2 measurements for the Company's commodity contracts are derived using forward curves supplied by industry-recognized and unrelated third-party services. The Level 2 measurements for the Company's available-for-sale securities are derived using market-based pricing provided by unrelated third-party services.
	There were no transfers in or out of Levels 1 and 2 of the fair value hierarchy for the three months ended March 31, 2014 and 2013.
	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.
		31-Mar-14					December 31, 2013
		Carrying		Fair			Carrying			Fair
		Value		Value			Value			Value
	3.60% senior notes due 2022	$	249,020	$	242,600		$	248,990		$	236,905
	6 ½% senior notes due 2029	100,000		113,000			100,000			109,490
	6 ¾% senior notes due 2032	250,000		281,775			250,000			265,148
	6 ½% GO Zone Senior Notes Due 2035	89,000		101,238			89,000			94,606
	6 ½% IKE Zone Senior Notes Due 2035	65,000		73,938			65,000			69,094
	Loan related to tax-exempt waste disposal revenue	10,889		10,889			10,889			10,889
	bonds due 2027

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The effective income tax rate was 34.5% for the three months ended March 31, 2014. The effective income tax rate for the 2014 period was below the U.S. federal statutory rate of 35.0% primarily due to state tax credits and the domestic manufacturing deduction, mostly offset by state income taxes. The effective income tax rate was 35.5% for the three months ended March 31, 2013. The effective income tax rate for the 2013 period was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.
	There was no material change to the total gross unrecognized tax benefits for the three months ended March 31, 2014. Management anticipates that all of the gross unrecognized tax benefits of $2,501 will be recognized within the next twelve months due to expiring statutes of limitations. The impact from the recognition of these tax benefits on the Company's effective tax rate is expected to be immaterial.
	The Company recognizes penalties and interest accrued related to unrecognized tax benefits in income tax expense. As of March 31, 2014, 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	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings per Share	'
	Earnings per Share
	The Company has unvested shares of restricted stock and restricted stock units outstanding that are considered participating securities and, therefore, computes basic and diluted earnings per share under the two-class method. Basic earnings per share for the periods are based upon the weighted average number of shares of common stock outstanding during the periods. Diluted earnings per share include the effect of certain stock options.
			Three Months Ended March 31,
			2014			2013
	Net income		$	158,032		$	123,347
	Less:
	Net income attributable to participating securities		(384		)	(568		)
	Net income attributable to common shareholders		$	157,648		$	122,779
	The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:
			Three Months Ended March 31,
			2014			2013
	Weighted average common shares—basic (1)		133,072,254			133,251,071
	Plus incremental shares from:
	Assumed exercise of options (1)		540,670			566,666
	Weighted average common shares—diluted (1)		133,612,924			133,817,737
	Earnings per share: (1)
	Basic		$	1.18		$	0.92
	Diluted		$	1.18		$	0.92
	_____________
	-1	Share amounts and per share data for the three months ended March 31, 2013 have been restated to reflect the effect of a two-for-one stock split on March 18, 2014. See Note 1 for additional information.
	Excluded from the computation of diluted earnings per share are options to purchase 69,662 and 72,776 shares of common stock for the three months ended March 31, 2014 and 2013, 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	3 Months Ended
	Mar. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Pension and Post-Retirement Benefit Costs	'
	Pension and Post-Retirement Benefit Costs
	Components of net periodic benefit cost are as follows:
		Three Months Ended March 31,
		Pension						Post-retirement
								Healthcare
		2014			2013			2014		2013
	Service cost	$	84		$	264		$	5	$	2
	Interest cost	595			501			181		147
	Expected return on plan assets	(809		)	(714		)	—		—
	Amortization of prior service cost	74			74			13		21
	Amortization of net loss	63			429			69		90
	Net periodic benefit cost	$	7		$	554		$	268	$	260
	The Company contributed $388 to the Salaried pension plan in the first three months of 2014, and contributed $290 and $60 to the Wage pension plan in the first three months of 2014 and 2013, respectively. The Company did not contribute to the Salaried pension plan in the first three months of 2013. The Company expects to make additional contributions of $2,389 to the Salaried pension plan and $916 to the Wage pension plan during the fiscal year ending December 31, 2014.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Accumulated Other Comprehensive Income	'
	Accumulated Other Comprehensive Loss
	Changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2014 and 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, 2013		$	(6,696	)		$	3,904			$	176		$	(2,616	)
	Other comprehensive (loss) income before		—				(898		)		1,581			683
	reclassifications
	Amounts reclassified from accumulated other		135				—				16			151
	comprehensive loss
	Net other comprehensive income (loss) for the period		135				(898		)		1,597			834
	Balances at March 31, 2014		$	(6,561	)		$	3,006			$	1,773		$	(1,782	)
			Benefits				Cumulative				Total
			Liability,				Foreign
			Net of Tax				Currency
							Exchange
	Balances at December 31, 2012		$	(16,351	)		$	5,511			$	(10,840	)
	Other comprehensive loss before reclassifications		—				(570		)		(570		)
	Amounts reclassified from accumulated other comprehensive loss		378				—				378
	Net other comprehensive income (loss) for the period		378				(570		)		(192		)
	Balances at March 31, 2013		$	(15,973	)		$	4,941			$	(11,032	)
	The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three months ended March 31, 2014 and 2013:
	Details about Accumulated Other Comprehensive		Location of Reclassification		Three Months Ended March 31,
	Income (Loss) Components		(Income (Expense)) in
			Consolidated Statements
			of Operations		2014				2013
	Amortization of pension and other post-retirement items
	Prior service costs		-1		$	(87	)		$	(95	)
	Net loss		-1		(132		)		(519		)
					(219		)		(614		)
			Provision for income taxes		84				236
					(135		)		(378		)
	Net unrealized gains on available-for-sale investments
	Realized loss on available-for-sale investments		Other income, net		(25		)		—
			Provision for income taxes		9				—
					(16		)		—
	Total reclassifications for the period				$	(151	)		$	(378	)
	_____________
	-1	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 10 (Employee Benefits) to the financial statements included in the 2013 Form 10-K.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	The Company is subject to environmental laws and regulations that can impose civil and criminal sanctions and that may require it to mitigate the effects of contamination caused by the release or disposal of hazardous substances into the environment. Under one law, the U.S. Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), an owner or operator of property may be held strictly liable for remediating contamination without regard to whether that person caused the contamination, and without regard to whether the practices that resulted in the contamination were legal at the time they occurred. Because several of the Company's production sites have a history of industrial use, it is impossible to predict precisely what effect these legal requirements will have on the Company.
	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 polyvinyl chloride ("PVC") facility, had been extensively contaminated under Goodrich's operations. In 1993, Goodrich spun off the predecessor of PolyOne Corporation ("PolyOne"), and that predecessor assumed Goodrich's indemnification obligations relating to preexisting contamination.
	In 2003, litigation arose among the Company, Goodrich and PolyOne with respect to the allocation of the cost of remediating contamination at the site. The parties settled this litigation in December 2007 and the case was dismissed. In the settlement the parties agreed that, among other things: (1) PolyOne would pay 100% of the costs (with specified exceptions), net of recoveries or credits from third parties, incurred with respect to environmental issues at the Calvert City site from August 1, 2007 forward; (2) either the Company or PolyOne might, from time to time in the future (but not more than once every five years), institute an arbitration proceeding to adjust that percentage; and (3) the Company and PolyOne would negotiate a new environmental remediation utilities and services agreement to cover the Company's provision to, or on behalf of, PolyOne of certain environmental remediation services at the site. The current environmental remediation activities at the Calvert City 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 $3,284 in 2013. By letter dated March 16, 2010, PolyOne notified the Company that it was initiating an arbitration proceeding under the settlement agreement. In this proceeding, PolyOne seeks to readjust the percentage allocation of costs and to recover approximately $1,400 from the Company in reimbursement of previously paid remediation costs. The arbitration is currently stayed.
	State Administrative Proceedings. There are several administrative proceedings in Kentucky involving the Company, Goodrich and PolyOne related to the same manufacturing 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, under the auspices of the U.S. Environmental Protection Agency ("EPA"), pursuant to an Administrative Settlement Agreement ("AOC"), which became effective on December 9, 2009. See "Federal Administrative Proceedings" below. The proceedings have been postponed. Periodic status conferences will be held to evaluate whether additional proceedings will be required.
	Federal Administrative Proceedings. In May 2009, the Cabinet sent a letter to the EPA requesting the EPA's assistance in addressing contamination at the Calvert City site under CERCLA. In its response to the Cabinet also in May 2009, the EPA stated that it concurred with the Cabinet's request and would incorporate work previously conducted under the Cabinet's RCRA authority into the EPA's cleanup efforts under CERCLA. Since 1983, the EPA has been addressing contamination at an abandoned landfill adjacent to the Company's plant which had been operated by Goodrich and which was being remediated pursuant to CERCLA. During the past three 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. On July 12, 2013, the parties submitted separate draft RIFS reports to the EPA. The EPA has hired a contractor to complete the remedial investigation report.
	Monetary Relief. Except as noted above with respect to the settlement of the contract litigation among the Company, Goodrich and PolyOne, none of the court, the Cabinet nor the EPA has established any allocation of the costs of remediation among the various parties that are involved in the judicial and administrative proceedings discussed above. At this time, the Company is not able to estimate the loss or reasonable possible loss, if any, on the Company's financial statements that could result from the resolution of these proceedings. Any cash expenditures that the Company might incur in the future with respect to the remediation of contamination at the 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	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	The Company operates in two principal operating segments: Olefins and Vinyls. These segments are strategic business units that offer a variety of different products. The Company manages each segment separately as each business requires different technology and marketing strategies.
		Three Months Ended March 31,
		2014			2013
	Net external sales
	Olefins
	Polyethylene	$	487,144		$	420,768
	Styrene, feedstock and other	235,654			162,077
	Total Olefins	722,798			582,845
	Vinyls
	PVC, caustic soda and other	190,527			195,246
	Building products	114,351			86,556
	Total Vinyls	304,878			281,802
		$	1,027,676		$	864,647
	Intersegment sales
	Olefins	$	56,853		$	70,283
	Vinyls	343			264
		$	57,196		$	70,547
	Income (loss) from operations
	Olefins	$	272,333		$	161,058
	Vinyls	(21,114		)	43,663
	Corporate and other	(3,164		)	(10,666		)
		$	248,055		$	194,055
	Depreciation and amortization
	Olefins	$	26,647		$	23,346
	Vinyls	19,168			11,884
	Corporate and other	157			126
		$	45,972		$	35,356
	Other income (expense), net
	Olefins	$	1,454		$	4,010
	Vinyls	(34		)	(425		)
	Corporate and other	1,089			(66		)
		$	2,509		$	3,519
	Provision for (benefit from) income taxes
	Olefins	$	93,550		$	55,477
	Vinyls	(10,070		)	13,720
	Corporate and other	(105		)	(1,251		)
		$	83,375		$	67,946
		Three Months Ended March 31,
		2014			2013
	Capital expenditures
	Olefins	$	29,074		$	50,040
	Vinyls	81,120			100,317
	Corporate and other	547			427
		$	110,741		$	150,784
	A reconciliation of total segment income from operations to consolidated income before income taxes is as follows:
		Three Months Ended March 31,
		2014			2013
	Income from operations	$	248,055		$	194,055
	Interest expense	(9,157		)	(6,281		)
	Other income, net	2,509			3,519
	Income before income taxes	$	241,407		$	191,293
		March 31,			December 31,
		2014			2013
	Total assets
	Olefins	$	1,556,856		$	1,557,510
	Vinyls	1,768,572			1,740,595
	Corporate and other	846,528			762,804
		$	4,171,956		$	4,060,909

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	Subsequent events were evaluated through the date on which the financial statements were issued.

Guarantor_Disclosures

Guarantor Disclosures	3 Months Ended
	Mar. 31, 2014
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 eliminations necessary to present the Company's results on a consolidated basis.
	Condensed Consolidating Financial Information as of March 31, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Balance Sheet
	Current assets
	Cash and cash equivalents	$	490,508		$	7,896		$	34,239		$	—		$	532,643
	Marketable securities	243,694			—			—			—			243,694
	Accounts receivable, net	58,050			888,829			3,381			(528,381		)	421,879
	Inventories	—			422,166			16,843			—			439,009
	Prepaid expenses and other	889			12,864			2,127			—			15,880
	current assets
	Deferred income taxes	441			33,422			295			—			34,158
	Total current assets	793,582			1,365,177			56,885			(528,381		)	1,687,263
	Property, plant and equipment, net	—			2,144,266			6,377			—			2,150,643
	Equity investments	2,975,949			101,472			31,056			(3,040,917		)	67,560
	Other assets, net	31,493			238,867			1,176			(5,046		)	266,490
	Total assets	$	3,801,024		$	3,849,782		$	95,494		$	(3,574,344	)	$	4,171,956
	Current liabilities
	Accounts payable	$	463,650		$	193,020		$	14,351		$	(459,069	)	$	211,952
	Accrued liabilities	15,782			200,781			731			(69,312		)	147,982
	Total current liabilities	479,432			393,801			15,082			(528,381		)	359,934
	Long-term debt	753,020			10,889			—			—			763,909
	Deferred income taxes	—			451,597			652			(5,046		)	447,203
	Other liabilities	—			32,308			30			—			32,338
	Stockholders' equity	2,568,572			2,961,187			79,730			(3,040,917		)	2,568,572
	Total liabilities and	$	3,801,024		$	3,849,782		$	95,494		$	(3,574,344	)	$	4,171,956
	stockholders' equity
	Condensed Consolidating Financial Information as of December 31, 2013
		Westlake			Guarantor			Non-Guarantor			Eliminations			Consolidated
		Chemical			Subsidiaries			Subsidiaries
		Corporation
	Balance Sheet
	Current assets
	Cash and cash equivalents	$	420,948		$	6,227		$	34,126		$	—		$	461,301
	Marketable securities	239,388			—			—			—			239,388
	Accounts receivable, net	3,879			738,156			2,755			(316,333		)	428,457
	Inventories	—			456,306			15,573			—			471,879
	Prepaid expenses and other	778			11,312			1,798			—			13,888
	current assets
	Deferred income taxes	441			33,422			306			—			34,169
	Total current assets	665,434			1,245,423			54,558			(316,333		)	1,649,082
	Property, plant and equipment, net	—			2,081,091			6,923			—			2,088,014
	Equity investments	2,815,752			100,326			31,518			(2,880,721		)	66,875
	Other assets, net	15,393			246,125			1,199			(5,779		)	256,938
	Total assets	$	3,496,579		$	3,672,965		$	94,198		$	(3,202,833	)	$	4,060,909
	Current liabilities
	Accounts payable	$	316,652		$	223,134		$	10,649		$	(300,822	)	$	249,613
	Accrued liabilities	8,334			161,140			1,282			(15,511		)	155,245
	Total current liabilities	324,986			384,274			11,931			(316,333		)	404,858
	Long-term debt	752,990			10,889			—			—			763,879
	Deferred income taxes	—			443,026			729			(5,779		)	437,976
	Other liabilities	—			35,533			60			—			35,593
	Stockholders' equity	2,418,603			2,799,243			81,478			(2,880,721		)	2,418,603
	Total liabilities and	$	3,496,579		$	3,672,965		$	94,198		$	(3,202,833	)	$	4,060,909
	stockholders' equity
	Condensed Consolidating Financial Information for the Three Months Ended March 31, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
Net sales	$	—		$	1,020,429		$	9,117		$	(1,870	)	$	1,027,676
Cost of sales	—			734,350			8,186			(1,870		)	740,666
Gross profit	—			286,079			931			—			287,010
Selling, general and administrative	546			37,063			1,346			—			38,955
expenses
(Loss) income from operations	(546		)	249,016			(415		)	—			248,055
Interest expense	(8,947		)	(210		)	—			—			(9,157		)
Other income (expense), net	5,006			(1,883		)	(614		)	—			2,509
(Loss) income before income taxes	(4,487		)	246,923			(1,029		)	—			241,407
(Benefit from) provision for income taxes	(1,558		)	85,110			(177		)	—			83,375
Equity in net income of subsidiaries	160,961			—			—			(160,961		)	—
Net income (loss)	$	158,032		$	161,813		$	(852	)	$	(160,961	)	$	158,032
Comprehensive income (loss)	$	158,866		$	161,948		$	(1,750	)	$	(160,198	)	$	158,866
Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Operations
Net sales	$	—		$	856,085		$	10,540		$	(1,978	)	$	864,647
Cost of sales	—			629,286			9,530			(1,978		)	636,838
Gross profit	—			226,799			1,010			—			227,809
Selling, general and administrative	510			31,709			1,535			—			33,754
expenses
(Loss) income from operations	(510		)	195,090			(525		)	—			194,055
Interest expense	(6,258		)	(23		)	—			—			(6,281		)
Other income (expense), net	4,309			(290		)	(500		)	—			3,519
(Loss) income before income taxes	(2,459		)	194,777			(1,025		)	—			191,293
(Benefit from) provision for income taxes	(874		)	69,051			(231		)	—			67,946
Equity in net income of subsidiaries	124,932			—			—			(124,932		)	—
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Comprehensive income (loss)	$	123,155		$	126,104		$	(1,364	)	$	(124,740	)	$	123,155
Condensed Consolidating Financial Information for the Three Months Ended March 31, 2014
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	158,032		$	161,813		$	(852	)	$	(160,961	)	$	158,032
Adjustments to reconcile net income
(loss) to net cash (used for) provided
by operating activities
Depreciation and amortization	365			45,408			564			—			46,337
Deferred income taxes	(162		)	8,487			(50		)	—			8,275
Net changes in working capital	(165,553		)	6,263			(1,810		)	160,961			(139		)
and other
Net cash (used for) provided by	(7,318		)	221,971			(2,148		)	—			212,505
operating activities
Cash flows from investing activities
Additions to property, plant and	—			(110,559		)	(182		)	—			(110,741		)
equipment
Proceeds from disposition of assets	—			12			—			—			12
Proceeds from sales and maturities of	30,119			—			—			—			30,119
securities
Purchase of securities	(49,025		)	—			—			—			(49,025		)
Settlements of derivative instruments	—			(409		)	—			—			(409		)
Net cash used for investing	(18,906		)	(110,956		)	(182		)	—			(130,044		)
activities
Cash flows from financing activities
Intercompany financing	106,903			(109,346		)	2,443			—			—
Dividends paid	(16,789		)	—			—			—			(16,789		)
Proceeds from exercise of stock options	2,158			—			—			—			2,158
Windfall tax benefits from share-based	3,512			—			—			—			3,512
payment arrangements
Net cash provided by (used for)	95,784			(109,346		)	2,443			—			(11,119		)
financing activities
Net increase in cash and cash equivalents	69,560			1,669			113			—			71,342
Cash and cash equivalents at beginning	420,948			6,227			34,126			—			461,301
of period
Cash and cash equivalents at end of period	$	490,508		$	7,896		$	34,239		$	—		$	532,643
Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
Adjustments to reconcile net income
(loss) to net cash (used for) provided
by operating activities
Depreciation and amortization	365			34,766			590			—			35,721
Deferred income taxes	(23		)	29,896			(407		)	—			29,466
Net changes in working capital	(129,403		)	(68,474		)	663			124,932			(72,282		)
and other
Net cash (used for) provided by	(5,714		)	121,914			52			—			116,252
operating activities
Cash flows from investing activities
Additions to property, plant and	—			(149,113		)	(1,671		)	—			(150,784		)
equipment
Proceeds from disposition of assets	—			—			2			—			2
Proceeds from repayment of loan	—			—			167			—			167
to affiliate
Proceeds from sales and maturities of	124,873			—			—			—			124,873
securities
Purchase of securities	(94,903		)	—			—			—			(94,903		)
Settlements of derivative instruments	—			(679		)	—			—			(679		)
Net cash provided by (used for)	29,970			(149,792		)	(1,502		)	—			(121,324		)
investing activities
Cash flows from financing activities
Intercompany financing	(28,120		)	28,553			(433		)	—			—
Dividends paid	(12,553		)	—			—			—			(12,553		)
Proceeds from exercise of stock options	1,590			—			—			—			1,590
Windfall tax benefits from share-based	3,844			—			—			—			3,844
payment arrangements
Net cash (used for) provided by	(35,239		)	28,553			(433		)	—			(7,119		)
financing activities
Net (decrease) increase in cash and	(10,983		)	675			(1,883		)	—			(12,191		)
cash equivalents
Cash and cash equivalents at beginning	753,881			6,973			29,224			—			790,078
of period
Cash and cash equivalents at end of period	$	742,898		$	7,648		$	27,341		$	—		$	777,887

Basis_of_Financial_Statements_

Basis of Financial Statements (Policies)	3 Months Ended
	Mar. 31, 2014
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, 2013 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, 2013 (the "2013 Form 10-K"), filed with the SEC on February 21, 2014. 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, 2013.
	In the opinion of the Company's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company's financial position as of March 31, 2014, its results of operations for the three months ended March 31, 2014 and 2013 and the changes in its cash position for the three months ended March 31, 2014 and 2013.
	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, 2014 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.
	On February 14, 2014, the Company's Board of Directors authorized a two-for-one split of the Company's common stock. Stockholders of record as of February 28, 2014 were entitled to one additional share for every share outstanding, which was distributed on March 18, 2014. The total number of authorized common stock shares and associated par value were unchanged by this stock split. All share amounts and per share data included in the accompanying consolidated financial statements and related notes have been restated to reflect the effect of the stock split.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	There are no recently issued accounting standards which are expected to impact the Company's consolidated financial position, results of operations or cash flows.

Financial_Instruments_Tables

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2014												Mar. 31, 2013
Investments, Debt and Equity Securities [Abstract]	'												'
Marketable Securities	'												'
													Investments in available-for-sale securities were classified as follows:
														March 31,		December 31,
														2014		2013
													Current	$	243,694	$	239,388
													Non-current	17,195		—
													Total available-for-sale securities	$	260,889	$	239,388
Available-for-sale Securities	'												'
	The cost, gross unrealized gains, gross unrealized losses and fair value of the Company’s available-for-sale securities were as follows:
			March 31, 2014
			Cost			Gross		Gross			Fair Value
						Unrealized		Unrealized
						Gains		Losses (1)
	Debt securities
	Corporate bonds		$	116,669		$	470	$	(41	)	$	117,098
	U.S. government debt (2)		102,201			133		(46		)	102,288
	Asset-backed securities		24,268			47		(7		)	24,308
	Equity securities		14,985			2,210		—			17,195
	Total available-for-sale securities		$	258,123		$	2,860	$	(94	)	$	260,889
			December 31, 2013
			Cost			Gross		Gross			Fair Value
						Unrealized		Unrealized
						Gains		Losses (1)
	Debt securities
	Corporate bonds		$	108,300		$	340	$	(69	)	$	108,571
	U.S. government debt (2)		106,335			60		(79		)	106,316
	Asset-backed securities		24,478			34		(11		)	24,501
	Total available-for-sale securities		$	239,113		$	434	$	(159	)	$	239,388
	_____________
	-1	All unrealized loss positions were held at a loss for less than 12 months.
	-2	U.S. Treasury obligations, U.S. government agency obligations and U.S government agency mortgage-backed securities.
Schedule of Realized Gain (Loss)	'												'
			Three Months Ended March 31,
			2014
	Proceeds from sales and maturities of securities		$	30,119
	Gross realized gains		13
	Gross realized losses		(38		)

Accounts_Receivable_Tables

Accounts Receivable (Tables)	3 Months Ended
	Mar. 31, 2014
Accounts Receivable, Net [Abstract]	'
Schedule Of Accounts Receivable	'
	Accounts receivable consist of the following:
		March 31,			December 31,
		2014			2013
	Trade customers	$	415,812		$	410,302
	Affiliates	287			315
	Allowance for doubtful accounts	(11,592		)	(11,741		)
		404,507			398,876
	Federal and state taxes	5,248			20,820
	Other	12,124			8,761
	Accounts receivable, net	$	421,879		$	428,457

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Schedule Of Inventory	'
	Inventories consist of the following:
		March 31,		December 31,
		2014		2013
	Finished products	$	240,339	$	232,658
	Feedstock, additives and chemicals	139,189		180,646
	Materials and supplies	59,481		58,575
	Inventories	$	439,009	$	471,879

LongTerm_Debt_Tables

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Schedule Of Long-Term Debt	'
	Long-term debt consists of the following:
		March 31,		December 31,
		2014		2013
	3.60% senior notes due 2022	$	249,020	$	248,990
	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	$	763,909	$	763,879

Derivative_Instruments_Tables

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Fair Values of Derivatives Instruments in Consolidated Balance Sheets	'
	The fair values of derivative instruments in the Company's consolidated balance sheets were as follows:
		Derivative Assets
		Balance Sheet Location	Fair Value as of
			March 31,			December 31,
			2014			2013
	Not designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	$	248		$	296
	Total derivative assets		$	248		$	296
		Derivative Liabilities
		Balance Sheet Location	Fair Value as of
			March 31,			December 31,
			2014			2013
	Not designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	$	54		$	176
	Total derivative liabilities		$	54		$	176
Impact of Derivatives Instruments Designated as Fair Value Hedges	'
	The following tables reflect the impact of derivative instruments designated as fair value hedges and the related hedged item on the Company's consolidated statements of operations. For the three months ended March 31, 2013, 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 March 31,
	Hedging Relationships	Recognized in
		Income on Derivative	2014			2013
	Commodity forward contracts	Cost of sales	$	—		$	(1,643	)
	Hedged Items in Fair Value	Location of Gain (Loss)	Three Months Ended March 31,
	Hedging Relationships	Recognized in
		Income on Hedged Items	2014			2013
	Firm commitment designated as the hedged item	Cost of sales	$	—		$	1,395
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 March 31,
	Hedging Instruments	Recognized in
		Income on Derivative	2014			2013
	Commodity forward contracts	Gross profit	$	(611	)	$	7,335

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
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:
		31-Mar-14
		Level 1		Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	—	$	248		$	248
	Risk management liabilities - Commodity forward contracts	—		(54		)	(54		)
	Available-for-sale marketable securities	100,603		160,286			260,889
		December 31, 2013
		Level 1		Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	48	$	248		$	296
	Risk management liabilities - Commodity forward contracts	—		(176		)	(176		)
	Available-for-sale marketable securities	91,595		147,793			239,388
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.
		31-Mar-14					December 31, 2013
		Carrying		Fair			Carrying			Fair
		Value		Value			Value			Value
	3.60% senior notes due 2022	$	249,020	$	242,600		$	248,990		$	236,905
	6 ½% senior notes due 2029	100,000		113,000			100,000			109,490
	6 ¾% senior notes due 2032	250,000		281,775			250,000			265,148
	6 ½% GO Zone Senior Notes Due 2035	89,000		101,238			89,000			94,606
	6 ½% IKE Zone Senior Notes Due 2035	65,000		73,938			65,000			69,094
	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)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Schedule Of Net Income Attributable To Common Stockholders	'
		Three Months Ended March 31,
		2014			2013
	Net income	$	158,032		$	123,347
	Less:
	Net income attributable to participating securities	(384		)	(568		)
	Net income attributable to common shareholders	$	157,648		$	122,779
Reconciliation Of Denominator For Basic And Diluted Earnings Per Share	'
	The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:
		Three Months Ended March 31,
		2014			2013
	Weighted average common shares—basic (1)	133,072,254			133,251,071
	Plus incremental shares from:
	Assumed exercise of options (1)	540,670			566,666
	Weighted average common shares—diluted (1)	133,612,924			133,817,737
	Earnings per share: (1)
	Basic	$	1.18		$	0.92
	Diluted	$	1.18		$	0.92

Pension_and_PostRetirement_Ben1

Pension and Post-Retirement Benefit Costs (Tables)	3 Months Ended
	Mar. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Components of Net Periodic Benefit Cost	'
	Components of net periodic benefit cost are as follows:
		Three Months Ended March 31,
		Pension						Post-retirement
								Healthcare
		2014			2013			2014		2013
	Service cost	$	84		$	264		$	5	$	2
	Interest cost	595			501			181		147
	Expected return on plan assets	(809		)	(714		)	—		—
	Amortization of prior service cost	74			74			13		21
	Amortization of net loss	63			429			69		90
	Net periodic benefit cost	$	7		$	554		$	268	$	260

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	'
	Changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2014 and 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, 2013		$	(6,696	)		$	3,904			$	176	$	(2,616	)
	Other comprehensive (loss) income before		—				(898		)		1,581		683
	reclassifications
	Amounts reclassified from accumulated other		135				—				16		151
	comprehensive loss
	Net other comprehensive income (loss) for the period		135				(898		)		1,597		834
	Balances at March 31, 2014		$	(6,561	)		$	3,006			$	1,773	$	(1,782	)
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	'
	The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three months ended March 31, 2014 and 2013:
	Details about Accumulated Other Comprehensive		Location of Reclassification		Three Months Ended March 31,
	Income (Loss) Components		(Income (Expense)) in
			Consolidated Statements
			of Operations		2014				2013
	Amortization of pension and other post-retirement items
	Prior service costs		-1		$	(87	)		$	(95	)
	Net loss		-1		(132		)		(519		)
					(219		)		(614		)
			Provision for income taxes		84				236
					(135		)		(378		)
	Net unrealized gains on available-for-sale investments
	Realized loss on available-for-sale investments		Other income, net		(25		)		—
			Provision for income taxes		9				—
					(16		)		—
	Total reclassifications for the period				$	(151	)		$	(378	)
	_____________
	-1	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 10 (Employee Benefits) to the financial statements included in the 2013 Form 10-K.

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Reporting Information	'
		Three Months Ended March 31,
		2014			2013
	Net external sales
	Olefins
	Polyethylene	$	487,144		$	420,768
	Styrene, feedstock and other	235,654			162,077
	Total Olefins	722,798			582,845
	Vinyls
	PVC, caustic soda and other	190,527			195,246
	Building products	114,351			86,556
	Total Vinyls	304,878			281,802
		$	1,027,676		$	864,647
	Intersegment sales
	Olefins	$	56,853		$	70,283
	Vinyls	343			264
		$	57,196		$	70,547
	Income (loss) from operations
	Olefins	$	272,333		$	161,058
	Vinyls	(21,114		)	43,663
	Corporate and other	(3,164		)	(10,666		)
		$	248,055		$	194,055
	Depreciation and amortization
	Olefins	$	26,647		$	23,346
	Vinyls	19,168			11,884
	Corporate and other	157			126
		$	45,972		$	35,356
	Other income (expense), net
	Olefins	$	1,454		$	4,010
	Vinyls	(34		)	(425		)
	Corporate and other	1,089			(66		)
		$	2,509		$	3,519
	Provision for (benefit from) income taxes
	Olefins	$	93,550		$	55,477
	Vinyls	(10,070		)	13,720
	Corporate and other	(105		)	(1,251		)
		$	83,375		$	67,946
		Three Months Ended March 31,
		2014			2013
	Capital expenditures
	Olefins	$	29,074		$	50,040
	Vinyls	81,120			100,317
	Corporate and other	547			427
		$	110,741		$	150,784
Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes	'
	A reconciliation of total segment income from operations to consolidated income before income taxes is as follows:
		Three Months Ended March 31,
		2014			2013
	Income from operations	$	248,055		$	194,055
	Interest expense	(9,157		)	(6,281		)
	Other income, net	2,509			3,519
	Income before income taxes	$	241,407		$	191,293
Total Assets	'
		March 31,			December 31,
		2014			2013
	Total assets
	Olefins	$	1,556,856		$	1,557,510
	Vinyls	1,768,572			1,740,595
	Corporate and other	846,528			762,804
		$	4,171,956		$	4,060,909

Guarantor_Disclosures_Tables

Guarantor Disclosures (Tables)	3 Months Ended
	Mar. 31, 2014
Guarantees [Abstract]	'
Condensed Consolidating Financial Information Balance Sheet	'
	Condensed Consolidating Financial Information as of March 31, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Balance Sheet
	Current assets
	Cash and cash equivalents	$	490,508		$	7,896		$	34,239		$	—		$	532,643
	Marketable securities	243,694			—			—			—			243,694
	Accounts receivable, net	58,050			888,829			3,381			(528,381		)	421,879
	Inventories	—			422,166			16,843			—			439,009
	Prepaid expenses and other	889			12,864			2,127			—			15,880
	current assets
	Deferred income taxes	441			33,422			295			—			34,158
	Total current assets	793,582			1,365,177			56,885			(528,381		)	1,687,263
	Property, plant and equipment, net	—			2,144,266			6,377			—			2,150,643
	Equity investments	2,975,949			101,472			31,056			(3,040,917		)	67,560
	Other assets, net	31,493			238,867			1,176			(5,046		)	266,490
	Total assets	$	3,801,024		$	3,849,782		$	95,494		$	(3,574,344	)	$	4,171,956
	Current liabilities
	Accounts payable	$	463,650		$	193,020		$	14,351		$	(459,069	)	$	211,952
	Accrued liabilities	15,782			200,781			731			(69,312		)	147,982
	Total current liabilities	479,432			393,801			15,082			(528,381		)	359,934
	Long-term debt	753,020			10,889			—			—			763,909
	Deferred income taxes	—			451,597			652			(5,046		)	447,203
	Other liabilities	—			32,308			30			—			32,338
	Stockholders' equity	2,568,572			2,961,187			79,730			(3,040,917		)	2,568,572
	Total liabilities and	$	3,801,024		$	3,849,782		$	95,494		$	(3,574,344	)	$	4,171,956
	stockholders' equity
	Condensed Consolidating Financial Information as of December 31, 2013
		Westlake			Guarantor			Non-Guarantor			Eliminations			Consolidated
		Chemical			Subsidiaries			Subsidiaries
		Corporation
	Balance Sheet
	Current assets
	Cash and cash equivalents	$	420,948		$	6,227		$	34,126		$	—		$	461,301
	Marketable securities	239,388			—			—			—			239,388
	Accounts receivable, net	3,879			738,156			2,755			(316,333		)	428,457
	Inventories	—			456,306			15,573			—			471,879
	Prepaid expenses and other	778			11,312			1,798			—			13,888
	current assets
	Deferred income taxes	441			33,422			306			—			34,169
	Total current assets	665,434			1,245,423			54,558			(316,333		)	1,649,082
	Property, plant and equipment, net	—			2,081,091			6,923			—			2,088,014
	Equity investments	2,815,752			100,326			31,518			(2,880,721		)	66,875
	Other assets, net	15,393			246,125			1,199			(5,779		)	256,938
	Total assets	$	3,496,579		$	3,672,965		$	94,198		$	(3,202,833	)	$	4,060,909
	Current liabilities
	Accounts payable	$	316,652		$	223,134		$	10,649		$	(300,822	)	$	249,613
	Accrued liabilities	8,334			161,140			1,282			(15,511		)	155,245
	Total current liabilities	324,986			384,274			11,931			(316,333		)	404,858
	Long-term debt	752,990			10,889			—			—			763,879
	Deferred income taxes	—			443,026			729			(5,779		)	437,976
	Other liabilities	—			35,533			60			—			35,593
	Stockholders' equity	2,418,603			2,799,243			81,478			(2,880,721		)	2,418,603
	Total liabilities and	$	3,496,579		$	3,672,965		$	94,198		$	(3,202,833	)	$	4,060,909
	stockholders' equity
Condensed Consolidating Financial Information Statement Of Operations	'
	Condensed Consolidating Financial Information for the Three Months Ended March 31, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
	Net sales	$	—		$	1,020,429		$	9,117		$	(1,870	)	$	1,027,676
	Cost of sales	—			734,350			8,186			(1,870		)	740,666
	Gross profit	—			286,079			931			—			287,010
	Selling, general and administrative	546			37,063			1,346			—			38,955
	expenses
	(Loss) income from operations	(546		)	249,016			(415		)	—			248,055
	Interest expense	(8,947		)	(210		)	—			—			(9,157		)
	Other income (expense), net	5,006			(1,883		)	(614		)	—			2,509
	(Loss) income before income taxes	(4,487		)	246,923			(1,029		)	—			241,407
	(Benefit from) provision for income taxes	(1,558		)	85,110			(177		)	—			83,375
	Equity in net income of subsidiaries	160,961			—			—			(160,961		)	—
	Net income (loss)	$	158,032		$	161,813		$	(852	)	$	(160,961	)	$	158,032
	Comprehensive income (loss)	$	158,866		$	161,948		$	(1,750	)	$	(160,198	)	$	158,866
	Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
	Net sales	$	—		$	856,085		$	10,540		$	(1,978	)	$	864,647
	Cost of sales	—			629,286			9,530			(1,978		)	636,838
	Gross profit	—			226,799			1,010			—			227,809
	Selling, general and administrative	510			31,709			1,535			—			33,754
	expenses
	(Loss) income from operations	(510		)	195,090			(525		)	—			194,055
	Interest expense	(6,258		)	(23		)	—			—			(6,281		)
	Other income (expense), net	4,309			(290		)	(500		)	—			3,519
	(Loss) income before income taxes	(2,459		)	194,777			(1,025		)	—			191,293
	(Benefit from) provision for income taxes	(874		)	69,051			(231		)	—			67,946
	Equity in net income of subsidiaries	124,932			—			—			(124,932		)	—
	Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
	Comprehensive income (loss)	$	123,155		$	126,104		$	(1,364	)	$	(124,740	)	$	123,155
Condensed Consolidating Financial Information Statement Of Cash Flows	'
	Condensed Consolidating Financial Information for the Three Months Ended March 31, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Cash Flows
	Cash flows from operating activities
	Net income (loss)	$	158,032		$	161,813		$	(852	)	$	(160,961	)	$	158,032
	Adjustments to reconcile net income
	(loss) to net cash (used for) provided
	by operating activities
	Depreciation and amortization	365			45,408			564			—			46,337
	Deferred income taxes	(162		)	8,487			(50		)	—			8,275
	Net changes in working capital	(165,553		)	6,263			(1,810		)	160,961			(139		)
	and other
	Net cash (used for) provided by	(7,318		)	221,971			(2,148		)	—			212,505
	operating activities
	Cash flows from investing activities
	Additions to property, plant and	—			(110,559		)	(182		)	—			(110,741		)
	equipment
	Proceeds from disposition of assets	—			12			—			—			12
	Proceeds from sales and maturities of	30,119			—			—			—			30,119
	securities
	Purchase of securities	(49,025		)	—			—			—			(49,025		)
	Settlements of derivative instruments	—			(409		)	—			—			(409		)
	Net cash used for investing	(18,906		)	(110,956		)	(182		)	—			(130,044		)
	activities
	Cash flows from financing activities
	Intercompany financing	106,903			(109,346		)	2,443			—			—
	Dividends paid	(16,789		)	—			—			—			(16,789		)
	Proceeds from exercise of stock options	2,158			—			—			—			2,158
	Windfall tax benefits from share-based	3,512			—			—			—			3,512
	payment arrangements
	Net cash provided by (used for)	95,784			(109,346		)	2,443			—			(11,119		)
	financing activities
	Net increase in cash and cash equivalents	69,560			1,669			113			—			71,342
	Cash and cash equivalents at beginning	420,948			6,227			34,126			—			461,301
	of period
	Cash and cash equivalents at end of period	$	490,508		$	7,896		$	34,239		$	—		$	532,643
	Condensed Consolidating Financial Information for the Three Months Ended March 31, 2013
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Cash Flows
	Cash flows from operating activities
	Net income (loss)	$	123,347		$	125,726		$	(794	)	$	(124,932	)	$	123,347
	Adjustments to reconcile net income
	(loss) to net cash (used for) provided
	by operating activities
	Depreciation and amortization	365			34,766			590			—			35,721
	Deferred income taxes	(23		)	29,896			(407		)	—			29,466
	Net changes in working capital	(129,403		)	(68,474		)	663			124,932			(72,282		)
	and other
	Net cash (used for) provided by	(5,714		)	121,914			52			—			116,252
	operating activities
	Cash flows from investing activities
	Additions to property, plant and	—			(149,113		)	(1,671		)	—			(150,784		)
	equipment
	Proceeds from disposition of assets	—			—			2			—			2
	Proceeds from repayment of loan	—			—			167			—			167
	to affiliate
	Proceeds from sales and maturities of	124,873			—			—			—			124,873
	securities
	Purchase of securities	(94,903		)	—			—			—			(94,903		)
Settlements of derivative instruments	—			(679		)	—			—			(679		)
Net cash provided by (used for)	29,970			(149,792		)	(1,502		)	—			(121,324		)
investing activities
Cash flows from financing activities
Intercompany financing	(28,120		)	28,553			(433		)	—			—
Dividends paid	(12,553		)	—			—			—			(12,553		)
Proceeds from exercise of stock options	1,590			—			—			—			1,590
Windfall tax benefits from share-based	3,844			—			—			—			3,844
payment arrangements
Net cash (used for) provided by	(35,239		)	28,553			(433		)	—			(7,119		)
financing activities
Net (decrease) increase in cash and	(10,983		)	675			(1,883		)	—			(12,191		)
cash equivalents
Cash and cash equivalents at beginning	753,881			6,973			29,224			—			790,078
of period
Cash and cash equivalents at end of period	$	742,898		$	7,648		$	27,341		$	—		$	777,887

Basis_of_Financial_Statements_1

Basis of Financial Statements Basis (Details)	0 Months Ended
	Feb. 14, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Stock split conversion ratio	2

Financial_Instruments_Cash_Equ

Financial Instruments Cash Equivalents (Details) (Held-to-maturity Securities, USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Held-to-maturity Securities	'	'
Cash Equivalents [Line Items]	'	'
Cash Equivalents, at Carrying Value	$411,527	$263,967

Financial_Instruments_Marketab

Financial Instruments Marketable Securities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'	'
Current	$243,694	$239,388
Noncurrent	17,195	0
Total Available-for-sale Securities	$260,889	$239,388

Financial_Instruments_Availabl

Financial Instruments Available-for-sale Securities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	$258,123	$239,113
GrossUnrealizedGain	2,860	434
GrossUnrealizedLoss	-94	-159
Fair Value	-260,889	-239,388
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	1,773	176
Available-for-sale Securities, Income Tax Expense on Change in Unrealized Holding Gain (Loss)	993	99
Proceeds from Sale of Available-for-sale Securities	30,119	'
Gross Realized Gains	13	'
Gross Realized Losses	38	'
Corporate bonds	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	116,669	108,300
GrossUnrealizedGain	470	340
GrossUnrealizedLoss	-41	-69
Fair Value	-117,098	-108,571
U.S. government debt	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	102,201	106,335
GrossUnrealizedGain	133	60
GrossUnrealizedLoss	-46	-79
Fair Value	-102,288	-106,316
Asset-backed securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	24,268	24,478
GrossUnrealizedGain	47	34
GrossUnrealizedLoss	-7	-11
Fair Value	-24,308	-24,501
Equity Securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	14,985	'
GrossUnrealizedGain	2,210	'
GrossUnrealizedLoss	0	'
Fair Value	($17,195)	'

Financial_Instruments_Maturity

Financial Instruments Maturity Periods for Investments (Details)	3 Months Ended
	Mar. 31, 2014
Corporate bonds | Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'1 month
Corporate bonds | Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'5 years
US Government Agencies Debt Securities [Member] | Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'1 month
US Government Agencies Debt Securities [Member] | Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'4 years
Mortgage-backed securities | Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'1 year
Mortgage-backed securities | Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'29 years
Asset-backed securities | Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'1 year
Asset-backed securities | Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Investment maturity period	'6 years

Accounts_Receivable_Details

Accounts Receivable (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts Receivable, Net [Abstract]	'	'
Trade customers	$415,812	$410,302
Affiliates	287	315
Allowance for doubtful accounts	-11,592	-11,741
Receivables from trade customers and affiliates, net	404,507	398,876
Federal and state taxes	5,248	20,820
Other	12,124	8,761
Accounts receivable, net	$421,879	$428,457

Inventories_Details

Inventories (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Finished products	$240,339	$232,658
Feedstock, additives and chemicals	139,189	180,646
Materials and supplies	59,481	58,575
Inventories	$439,009	$471,879

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'	'	'
Property, plant and equipment	$2,150,643	'	$2,088,014
Depreciation expense on property, plant and equipment	$38,061	$30,920	'

Other_Assets_Additional_Inform

Other Assets (Additional Information) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013
			Olefins	Olefins	Vinyls	Vinyls
Segment Reporting Information [Line Items]	'	'	'	'	'	'
Goodwill	'	'	$29,990	$29,990	$32,026	$32,026
Amortization expense on intangible assets, included in other assets	$8,276	$4,801	'	'	'	'

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Long-term debt	$763,909	$763,879
3.60% Senior Notes Due 2022	'	'
Debt Instrument [Line Items]	'	'
Maturity	'2022	'
Stated interest rate	3.60%	'
Senior notes	249,020	248,990
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	Mar. 31, 2014
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
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'	'
Stock-based compensation expense	$2,222	$1,499

Derivative_Instruments_Textual

Derivative Instruments (Textual) (Detail) (Commodity Forward Contracts [Member], Designated As Fair Value Hedges)	Mar. 31, 2014
	customer
Commodity Forward Contracts [Member] | Designated As Fair Value Hedges	'
Derivative [Line Items]	'
Derivative, Number of Instruments Held	0

Derivative_Instruments_Fair_Va

Derivative Instruments (Fair Values of Derivative Instruments in Consolidated Balance Sheets) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative liabilities	$54	$176
Accounts Receivable	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative assets	248	296
Forward Contracts [Member] | Accrued Liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Not designated as hedging instruments, Derivative Liabilities	54	176
Forward Contracts [Member] | Accounts Receivable	'	'
Derivatives, Fair Value [Line Items]	'	'
Not designated as hedging instruments, Derivative Assets	$248	$296

Derivative_Instruments_Impact_

Derivative Instruments (Impact of Derivative Instruments on Income) (Details) (Cost of Sales, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
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	$0	$1,395
Designated As Fair Value Hedges | Forward Contracts [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss) Recognized in Income on Derivative	0	-1,643
Derivatives Not Designated As Hedging Instruments | Forward Contracts [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss) Recognized in Income on Derivative	($611)	$7,335

Fair_Value_Measurements_Summar

Fair Value Measurements (Summary of Assets and Liabilities Accounted at Fair Value on Recurring Basis) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for Sale	$243,694	$239,388
Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for Sale	260,889	239,388
Recurring | Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for Sale	100,603	91,595
Recurring | Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for Sale	160,286	147,793
Recurring | Forward Contracts [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Risk management assets - Commodity forward contracts	248	296
Risk management liabilities - Commodity forward contracts	-54	-176
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	0	48
Risk management liabilities - Commodity forward contracts	0	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	248	248
Risk management liabilities - Commodity forward contracts	($54)	($176)

Fair_Value_Measurements_Summar1

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

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

In Thousands, unless otherwise specified

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

3.60% Senior Notes Due 2022

3.60% Senior Notes Due 2022

3.60% Senior Notes Due 2022

3.60% Senior Notes Due 2022

3.60% Senior Notes Due 2022

6 1/2% Senior Notes Due 2029

6 1/2% Senior Notes Due 2029

6 1/2% Senior Notes Due 2029

6 1/2% Senior Notes Due 2029

6 1/2% Senior Notes Due 2029

6 3/4% Senior Notes Due 2032

6 3/4% Senior Notes Due 2032

6 3/4% Senior Notes Due 2032

6 3/4% Senior Notes Due 2032

6 3/4% Senior Notes Due 2032

2035 GO Zone 6 1/2% Notes

2035 GO Zone 6 1/2% Notes

2035 GO Zone 6 1/2% Notes

2035 GO Zone 6 1/2% Notes

2035 GO Zone 6 1/2% Notes

2035 IKE Zone 6 1/2% Notes

2035 IKE Zone 6 1/2% Notes

2035 IKE Zone 6 1/2% Notes

2035 IKE Zone 6 1/2% Notes

2035 IKE Zone 6 1/2% Notes

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

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

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

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

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

Carrying Value

Carrying Value

Fair Value

Fair Value

Carrying Value

Carrying Value

Fair Value

Fair Value

Carrying Value

Carrying Value

Fair Value

Fair Value

Carrying Value

Carrying Value

Fair Value

Fair Value

Carrying Value

Carrying Value

Fair Value

Fair Value

Carrying Value

Carrying Value

Fair Value

Fair Value

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maturity

'2022

'

'

'

'

'2029

'

'

'

'

'2032

'

'

'

'

'2035

'

'

'

'

'2035

'

'

'

'

'2027

'

'

'

'

Stated interest rate

3.60%

'

'

'

'

6.50%

'

'

'

'

6.75%

'

'

'

'

6.50%

'

'

'

'

6.50%

'

'

'

'

'

'

'

'

'

Senior notes

'

$249,020

$248,990

$242,600

$236,905

'

$100,000

$100,000

$113,000

$109,490

'

$250,000

$250,000

$281,775

$265,148

'

$89,000

$89,000

$101,238

$94,606

'

$65,000

$65,000

$73,938

$69,094

'

'

'

'

'

Loans

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$10,889

$10,889

$10,889

$10,889

Income_Taxes_Detail

Income Taxes (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]	'	'
Effective income tax rate	34.50%	35.50%
U.S. federal statutory income tax rate	35.00%	35.00%
Anticipated reductions to unrecognized tax benefits within next twelve months	$2,501	'

Earnings_per_Share_Additional_

Earnings per Share (Additional Information) (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	69,662	72,776

Earnings_per_Share_Schedule_of

Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Net income	$158,032	$123,347
Less: Net income attributable to participating securities	-384	-568
Net income attributable to common shareholders	$157,648	$122,779

Earnings_per_Share_Reconciliat

Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) (USD $)	0 Months Ended	3 Months Ended
	Feb. 14, 2014	Mar. 31, 2014		Mar. 31, 2013
Earnings Per Share [Abstract]	'	'		'
Basic	'	133,072,254	[1]	133,251,071	[1]
Plus incremental shares from: Assumed exercise of options	'	540,670	[1]	566,666	[1]
Weighted average common shares-diluted	'	133,612,924	[1]	133,817,737	[1]
Earnings per share: Basic	'	$1.18	[1]	$0.92	[1]
Earnings per share: Diluted	'	$1.18	[1]	$0.92	[1]
Stock split conversion ratio	2	'		'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	'	69,662		72,776
[1]	Share amounts and per share data for the three months ended March 31, 2013 have been restated to reflect the effect of a two-for-one stock split on MarchB 18, 2014. See Note 1 for additional information.

Pension_and_PostRetirement_Ben2

Pension and Post-Retirement Benefit Costs (Components of Net Periodic Benefit Cost) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Pension	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	$84	$264
Interest cost	595	501
Expected return on plan assets	-809	-714
Amortization of prior service cost	74	74
Amortization of net loss	63	429
Net periodic benefit cost	7	554
Post-Retirement Healthcare	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	5	2
Interest cost	181	147
Expected return on plan assets	0	0
Amortization of prior service cost	13	21
Amortization of net loss	69	90
Net periodic benefit cost	$268	$260

Pension_and_PostRetirement_Ben3

Pension and Post-Retirement Benefit Costs (Additional Information) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]	'	'
Document Fiscal Year Focus	'2014	'
Salaried Pension Plan	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Employer contribution	$388	'
Expected additional contributions	2,389	'
Wage Pension Plan	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Employer contribution	290	60
Expected additional contributions	$916	'

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income Changes in AOCI (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	($2,616)	($10,840)
Other comprehensive loss before reclassifications	683	-570
Amounts reclassified from accumulated other comprehensive loss	151	378
Net other comprehensive income (loss) for the period	834	-192
Accumulated other comprehensive income (loss), ending balance	-1,782	-11,032
Benefits Liability, Net of Tax	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	-6,696	-16,351
Other comprehensive loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	135	378
Net other comprehensive income (loss) for the period	135	378
Accumulated other comprehensive income (loss), ending balance	-6,561	-15,973
Cumulative Foreign Currency Exchange	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	3,904	5,511
Other comprehensive loss before reclassifications	-898	-570
Amounts reclassified from accumulated other comprehensive loss	0	0
Net other comprehensive income (loss) for the period	-898	-570
Accumulated other comprehensive income (loss), ending balance	3,006	4,941
Net Unrealized Holding Gains on Investmetnts, Net of Tax	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	176	'
Other comprehensive loss before reclassifications	1,581	'
Amounts reclassified from accumulated other comprehensive loss	16	'
Net other comprehensive income (loss) for the period	1,597	'
Accumulated other comprehensive income (loss), ending balance	$1,773	'

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income Reclassifications in AOCI (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Income before income taxes	$241,407		$191,293
Provision for income taxes	-83,375		-67,946
Net income	158,032		123,347
Nonoperating Income (Expense)	2,509		3,519
Reclassification out of Accumulated Other Comprehensive Income	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Net income	-151		-378
Accumulated Defined Benefit Plans Adjustment | Reclassification out of Accumulated Other Comprehensive Income	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Prior service costs	-87	[1]	-95	[1]
Net loss	-132	[1]	-519	[1]
Income before income taxes	-219		-614
Provision for income taxes	84		236
Net income	-135		-378
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Provision for income taxes	9		0
Net income	-16		0
Nonoperating Income (Expense)	($25)		$0
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. For additional information, please read Note 10 (Employee Benefits) to the financial statements included in the 2013 Form 10-K.

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, 2013
			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	'	'	'	$3,284

Segment_Information_Additional

Segment Information (Additional Information) (Detail)	3 Months Ended
	Mar. 31, 2014
	Segment
Segment Reporting [Abstract]	'
Number of segments	2

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]	'	'
Net external sales	$1,027,676	$864,647
Income (loss) from operations	248,055	194,055
Depreciation and amortization	45,972	35,356
Other (expense) income, net	2,509	3,519
Provision for (benefit from) income taxes	83,375	67,946
Capital expenditures	110,741	150,784
Olefins	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	722,798	582,845
Income (loss) from operations	272,333	161,058
Depreciation and amortization	26,647	23,346
Other (expense) income, net	1,454	4,010
Provision for (benefit from) income taxes	93,550	55,477
Capital expenditures	29,074	50,040
Vinyls	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	304,878	281,802
Income (loss) from operations	-21,114	43,663
Depreciation and amortization	19,168	11,884
Other (expense) income, net	-34	-425
Provision for (benefit from) income taxes	-10,070	13,720
Capital expenditures	81,120	100,317
Corporate and Other	'	'
Segment Reporting Information [Line Items]	'	'
Income (loss) from operations	-3,164	-10,666
Depreciation and amortization	157	126
Other (expense) income, net	1,089	-66
Provision for (benefit from) income taxes	-105	-1,251
Capital expenditures	547	427
Polyethylene | Olefins	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	487,144	420,768
Ethylene, Styrene And Other | Olefins	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	235,654	162,077
PVC, Caustic Soda And Other | Vinyls	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	190,527	195,246
Building Products | Vinyls	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	114,351	86,556
Intersegment sales	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	57,196	70,547
Intersegment sales | Olefins	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	56,853	70,283
Intersegment sales | Vinyls	'	'
Segment Reporting Information [Line Items]	'	'
Net external sales	$343	$264

Segment_Information_Reconcilia

Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting [Abstract]	'	'
Income from operations	$248,055	$194,055
Interest expense	-9,157	-6,281
Other (expense) income, net	2,509	3,519
Income before income taxes	$241,407	$191,293

Segment_Information_Total_Asse

Segment Information (Total Assets) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	$4,171,956	$4,060,909
Olefins	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	1,556,856	1,557,510
Vinyls	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	1,768,572	1,740,595
Corporate and Other	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	$846,528	$762,804

Guarantor_Disclosures_Addition

Guarantor Disclosures (Additional Information) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
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 $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	$532,643	$461,301	$777,887	$790,078
Marketable Securities, Current	243,694	239,388	'	'
Accounts receivable, net	421,879	428,457	'	'
Inventories	439,009	471,879	'	'
Prepaid expenses and other current assets	15,880	13,888	'	'
Deferred income taxes	34,158	34,169	'	'
Total current assets	1,687,263	1,649,082	'	'
Property, plant and equipment, net	2,150,643	2,088,014	'	'
Equity investments	67,560	66,875	'	'
Other assets, net	266,490	256,938	'	'
Total assets	4,171,956	4,060,909	'	'
Accounts payable	211,952	249,613	'	'
Accrued liabilities	147,982	155,245	'	'
Total current liabilities	359,934	404,858	'	'
Long-term debt	763,909	763,879	'	'
Deferred income taxes	447,203	437,976	'	'
Other liabilities	32,338	35,593	'	'
Stockholders' equity	2,568,572	2,418,603	'	'
Total liabilities and stockholders' equity	4,171,956	4,060,909	'	'
Westlake Chemical Corporation	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	490,508	420,948	742,898	753,881
Marketable Securities, Current	243,694	239,388	'	'
Accounts receivable, net	58,050	3,879	'	'
Inventories	0	0	'	'
Prepaid expenses and other current assets	889	778	'	'
Deferred income taxes	441	441	'	'
Total current assets	793,582	665,434	'	'
Property, plant and equipment, net	0	0	'	'
Equity investments	2,975,949	2,815,752	'	'
Other assets, net	31,493	15,393	'	'
Total assets	3,801,024	3,496,579	'	'
Accounts payable	463,650	316,652	'	'
Accrued liabilities	15,782	8,334	'	'
Total current liabilities	479,432	324,986	'	'
Long-term debt	753,020	752,990	'	'
Deferred income taxes	0	0	'	'
Other liabilities	0	0	'	'
Stockholders' equity	2,568,572	2,418,603	'	'
Total liabilities and stockholders' equity	3,801,024	3,496,579	'	'
Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	7,896	6,227	7,648	6,973
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	888,829	738,156	'	'
Inventories	422,166	456,306	'	'
Prepaid expenses and other current assets	12,864	11,312	'	'
Deferred income taxes	33,422	33,422	'	'
Total current assets	1,365,177	1,245,423	'	'
Property, plant and equipment, net	2,144,266	2,081,091	'	'
Equity investments	101,472	100,326	'	'
Other assets, net	238,867	246,125	'	'
Total assets	3,849,782	3,672,965	'	'
Accounts payable	193,020	223,134	'	'
Accrued liabilities	200,781	161,140	'	'
Total current liabilities	393,801	384,274	'	'
Long-term debt	10,889	10,889	'	'
Deferred income taxes	451,597	443,026	'	'
Other liabilities	32,308	35,533	'	'
Stockholders' equity	2,961,187	2,799,243	'	'
Total liabilities and stockholders' equity	3,849,782	3,672,965	'	'
Non-Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	34,239	34,126	27,341	29,224
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	3,381	2,755	'	'
Inventories	16,843	15,573	'	'
Prepaid expenses and other current assets	2,127	1,798	'	'
Deferred income taxes	295	306	'	'
Total current assets	56,885	54,558	'	'
Property, plant and equipment, net	6,377	6,923	'	'
Equity investments	31,056	31,518	'	'
Other assets, net	1,176	1,199	'	'
Total assets	95,494	94,198	'	'
Accounts payable	14,351	10,649	'	'
Accrued liabilities	731	1,282	'	'
Total current liabilities	15,082	11,931	'	'
Long-term debt	0	0	'	'
Deferred income taxes	652	729	'	'
Other liabilities	30	60	'	'
Stockholders' equity	79,730	81,478	'	'
Total liabilities and stockholders' equity	95,494	94,198	'	'
Eliminations	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	0	0	0	0
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	-528,381	-316,333	'	'
Inventories	0	0	'	'
Prepaid expenses and other current assets	0	0	'	'
Deferred income taxes	0	0	'	'
Total current assets	-528,381	-316,333	'	'
Property, plant and equipment, net	0	0	'	'
Equity investments	-3,040,917	-2,880,721	'	'
Other assets, net	-5,046	-5,779	'	'
Total assets	-3,574,344	-3,202,833	'	'
Accounts payable	-459,069	-300,822	'	'
Accrued liabilities	-69,312	-15,511	'	'
Total current liabilities	-528,381	-316,333	'	'
Long-term debt	0	0	'	'
Deferred income taxes	-5,046	-5,779	'	'
Other liabilities	0	0	'	'
Stockholders' equity	-3,040,917	-2,880,721	'	'
Total liabilities and stockholders' equity	($3,574,344)	($3,202,833)	'	'

Guarantor_Disclosures_Condense1

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Net sales	$1,027,676	$864,647
Cost of sales	740,666	636,838
Gross profit	287,010	227,809
Selling, general and administrative expenses	38,955	33,754
Income from operations	248,055	194,055
Interest expense	-9,157	-6,281
Other (expense) income, net	2,509	3,519
Income before income taxes	241,407	191,293
Provision for (benefit from) income taxes	83,375	67,946
Equity in net income of subsidiaries	0	0
Net income	158,032	123,347
Comprehensive income (loss)	158,866	123,155
Westlake Chemical Corporation	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general and administrative expenses	546	510
Income from operations	-546	-510
Interest expense	-8,947	-6,258
Other (expense) income, net	5,006	4,309
Income before income taxes	-4,487	-2,459
Provision for (benefit from) income taxes	-1,558	-874
Equity in net income of subsidiaries	160,961	124,932
Net income	158,032	123,347
Comprehensive income (loss)	158,866	123,155
Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net sales	1,020,429	856,085
Cost of sales	734,350	629,286
Gross profit	286,079	226,799
Selling, general and administrative expenses	37,063	31,709
Income from operations	249,016	195,090
Interest expense	-210	-23
Other (expense) income, net	-1,883	-290
Income before income taxes	246,923	194,777
Provision for (benefit from) income taxes	85,110	69,051
Equity in net income of subsidiaries	0	0
Net income	161,813	125,726
Comprehensive income (loss)	161,948	126,104
Non-Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net sales	9,117	10,540
Cost of sales	8,186	9,530
Gross profit	931	1,010
Selling, general and administrative expenses	1,346	1,535
Income from operations	-415	-525
Interest expense	0	0
Other (expense) income, net	-614	-500
Income before income taxes	-1,029	-1,025
Provision for (benefit from) income taxes	-177	-231
Equity in net income of subsidiaries	0	0
Net income	-852	-794
Comprehensive income (loss)	-1,750	-1,364
Eliminations	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net sales	-1,870	-1,978
Cost of sales	-1,870	-1,978
Gross profit	0	0
Selling, general and administrative expenses	0	0
Income from operations	0	0
Interest expense	0	0
Other (expense) income, net	0	0
Income before income taxes	0	0
Provision for (benefit from) income taxes	0	0
Equity in net income of subsidiaries	-160,961	-124,932
Net income	-160,961	-124,932
Comprehensive income (loss)	($160,198)	($124,740)

Guarantor_Disclosures_Condense2

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	$158,032	$123,347
Depreciation and amortization	46,337	35,721
Deferred income taxes	8,275	29,466
Net changes in working capital and other	-139	-72,282
Net cash provided by operating activities	212,505	116,252
Additions to property, plant and equipment	-110,741	-150,784
Proceeds from disposition of assets	12	2
Proceeds from repayment of loan to affiliate	0	167
Proceeds from sales of equity securities	30,119	124,873
Purchase of securities and other investments	-49,025	-94,903
Settlements of derivative instruments	-409	-679
Net cash used for investing activities	-130,044	-121,324
Intercompany financing	0	0
Dividends paid	-16,789	-12,553
Proceeds from exercise of stock options	2,158	1,590
Windfall tax benefits from share-based payment arrangements	3,512	3,844
Net cash provided by financing activities	-11,119	-7,119
Net increase in cash and cash equivalents	71,342	-12,191
Cash and cash equivalents at beginning of period	461,301	790,078
Cash and cash equivalents at end of period	532,643	777,887
Westlake Chemical Corporation	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	158,032	123,347
Depreciation and amortization	365	365
Deferred income taxes	-162	-23
Net changes in working capital and other	-165,553	-129,403
Net cash provided by operating activities	-7,318	-5,714
Additions to property, plant and equipment	0	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	'	0
Proceeds from sales of equity securities	30,119	124,873
Purchase of securities and other investments	-49,025	-94,903
Settlements of derivative instruments	0	0
Net cash used for investing activities	-18,906	29,970
Intercompany financing	106,903	-28,120
Dividends paid	-16,789	-12,553
Proceeds from exercise of stock options	2,158	1,590
Windfall tax benefits from share-based payment arrangements	3,512	3,844
Net cash provided by financing activities	95,784	-35,239
Net increase in cash and cash equivalents	69,560	-10,983
Cash and cash equivalents at beginning of period	420,948	753,881
Cash and cash equivalents at end of period	490,508	742,898
Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	161,813	125,726
Depreciation and amortization	45,408	34,766
Deferred income taxes	8,487	29,896
Net changes in working capital and other	6,263	-68,474
Net cash provided by operating activities	221,971	121,914
Additions to property, plant and equipment	-110,559	-149,113
Proceeds from disposition of assets	12	0
Proceeds from repayment of loan to affiliate	'	0
Proceeds from sales of equity securities	0	0
Purchase of securities and other investments	0	0
Settlements of derivative instruments	-409	-679
Net cash used for investing activities	-110,956	-149,792
Intercompany financing	-109,346	28,553
Dividends paid	0	0
Proceeds from exercise of stock options	0	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	-109,346	28,553
Net increase in cash and cash equivalents	1,669	675
Cash and cash equivalents at beginning of period	6,227	6,973
Cash and cash equivalents at end of period	7,896	7,648
Non-Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	-852	-794
Depreciation and amortization	564	590
Deferred income taxes	-50	-407
Net changes in working capital and other	-1,810	663
Net cash provided by operating activities	-2,148	52
Additions to property, plant and equipment	-182	-1,671
Proceeds from disposition of assets	0	2
Proceeds from repayment of loan to affiliate	'	167
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	-182	-1,502
Intercompany financing	2,443	-433
Dividends paid	0	0
Proceeds from exercise of stock options	0	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	2,443	-433
Net increase in cash and cash equivalents	113	-1,883
Cash and cash equivalents at beginning of period	34,126	29,224
Cash and cash equivalents at end of period	34,239	27,341
Eliminations	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	-160,961	-124,932
Depreciation and amortization	0	0
Deferred income taxes	0	0
Net changes in working capital and other	160,961	124,932
Net cash provided by operating activities	0	0
Additions to property, plant and equipment	0	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	'	0
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
Dividends paid	0	0
Proceeds from exercise of stock options	0	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