Westlake (WLK) 10-Q 6 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Jul. 30, 2014
Document Documentand Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'WLK	'
Entity Registrant Name	'WESTLAKE CHEMICAL CORP	'
Entity Central Index Key	'0001262823	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	133,486,747

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$876,067	$461,301
Marketable Securities, Current	0	239,388
Accounts receivable, net	454,281	428,457
Inventories	437,519	471,879
Prepaid expenses and other current assets	20,468	13,888
Deferred income taxes	34,168	34,169
Total current assets	1,822,503	1,649,082
Property, plant and equipment, net	2,217,049	2,088,014
Equity investments	68,867	66,875
Other assets, net	'	'
Intangible assets, net	155,394	159,046
Deferred charges and other assets	105,556	97,892
Total other assets, net	260,950	256,938
Total assets	4,369,369	4,060,909
Current liabilities	'	'
Accounts payable	219,600	249,613
Accrued liabilities	167,329	155,245
Total current liabilities	386,929	404,858
Long-term debt	763,938	763,879
Deferred income taxes	458,790	437,976
Other liabilities	31,639	35,593
Total liabilities	1,641,296	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, 300,000,000 shares authorized; 134,681,372 and 134,580,208 shares issued at June 30, 2014 and December 31, 2013, respectively (Note 1)	1,347	1,346
Common stock, held in treasury, at cost; 1,197,617 and 1,252,922 shares at June 30, 2014 and December 31, 2013, respectively (Note 1)	-45,181	-46,220
Additional paid-in capital	523,526	511,432
Retained earnings	2,248,513	1,954,661
Accumulated other comprehensive loss	-132	-2,616
Total stockholders' equity	2,728,073	2,418,603
Total liabilities and stockholders' equity	$4,369,369	$4,060,909

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 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	300,000,000	150,000,000
Common stock, shares issued	134,681,372	134,580,208
Common stock, held in treasury	1,197,617	1,252,922

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended				6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Income Statement [Abstract]	'		'		'		'
Net sales	$998,576		$939,047		$2,026,252		$1,803,694
Cost of sales	692,605		665,560		1,433,271		1,302,398
Gross profit	305,971		273,487		592,981		501,296
Selling, general and administrative expenses	39,183		38,260		78,138		72,014
Income from operations	266,788		235,227		514,843		429,282
Other income (expense)	'		'		'		'
Interest expense	-9,539		-5,343		-18,696		-11,624
Other (expense) income, net	4,601		-95		7,110		3,424
Income before income taxes	261,850		229,789		503,257		421,082
Provision for income taxes	92,407		83,973		175,782		151,919
Net income	$169,443		$145,816		$327,475		$269,163
Earnings per share:	'		'		'		'
Basic	$1.27	[1]	$1.09	[1]	$2.45	[1]	$2.01	[1]
Diluted	$1.26	[1]	$1.09	[1]	$2.44	[1]	$2.01	[1]
Weighted average shares outstanding:	'		'		'		'
Basic	133,223,705	[1]	133,259,218	[1]	133,148,398	[1]	133,255,322	[1]
Diluted	133,767,890	[1]	133,791,190	[1]	133,690,836	[1]	133,804,546	[1]
Dividends per common share	$0.13		$0.09		$0.25		$0.19
[1]	Share amounts and per share data for the three and six months ended June 30, 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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income	$169,443	$145,816	$327,475	$269,163
Pension and other post-retirement reserves adjustment (excluding amortization)	31	489	31	489
Pension and other post-retirement benefits liability	'	'	'	'
Amortization of benefits liability	226	695	445	1,309
Income tax provision on pension and other post-retirement benefits liability	-75	-80	-159	-316
Foreign currency translation adjustments	808	-820	-90	-1,390
Available-for-sale investments	'	'	'	'
Unrealized holding gains on investments	2,364	0	4,831	0
Reclassification of net realized gains to net income	1,237	0	1,212	0
Income tax provision on available-for-sale investments	405	0	1,300	0
Other comprehensive income (loss)	1,650	-694	2,484	-886
Comprehensive income	$171,093	$145,122	$329,959	$268,277

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Repurchase of common stock for treasury	$0	$13,283
Payments to Acquire Businesses, Net of Cash Acquired	0	178,309
Payments to Acquire Equity Method Investments	0	6,113
Cash flows from operating activities	'	'
Net income	327,475	269,163
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	94,474	75,566
Provision for (recovery of) doubtful accounts	311	3,607
Amortization of debt issuance costs	730	729
Stock-based compensation expense	4,511	3,124
Loss from disposition of fixed assets	1,872	4,125
Deferred income taxes	19,359	60,425
Windfall tax benefits from share-based payment arrangements	-4,436	-4,576
Equity in (income) loss of joint ventures	-1,239	1,369
Other Operating Activities, Cash Flow Statement	-526	0
Changes in operating assets and liabilities	'	'
Accounts receivable	-27,367	-61,494
Inventories	34,360	-1,893
Prepaid expenses and other current assets	-5,480	-7,947
Accounts payable	-21,990	5,217
Accrued liabilities	13,631	-32,382
Other, net	-3,443	-59,553
Net cash provided by operating activities	432,242	255,480
Cash flows from investing activities	'	'
Additions to property, plant and equipment	-216,912	-297,873
Payments for Construction of Assets Pending Sale Leaseback	0	-136
Proceeds from disposition of assets	13	62
Proceeds from repayment of loan to affiliate	0	167
Proceeds from sale and maturities of securities	342,045	209,785
Purchase of securities and other investments	-117,332	-114,881
Settlements of derivative instruments	-290	-1,588
Net cash used for investing activities	7,524	-388,886
Cash flows from financing activities	'	'
Dividends paid	-33,623	-25,120
Proceeds from exercise of stock options	4,187	2,656
Windfall tax benefits from share-based payment arrangements	4,436	4,576
Net cash provided by financing activities	-25,000	-31,171
Net increase in cash and cash equivalents	414,766	-164,577
Cash and cash equivalents at beginning of period	461,301	790,078
Cash and cash equivalents at end of period	$876,067	$625,501

Basis_of_Financial_Statements

Basis of Financial Statements	6 Months Ended
	Jun. 30, 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 June 30, 2014, its results of operations for the three and six months ended June 30, 2014 and 2013 and the changes in its cash position for the six months ended June 30, 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
	Revenue from Contracts with Customers
	In May 2014, the Financial Accounting Standards Board (“FASB”) issued an accounting standards update on a comprehensive new revenue recognition standard that will supersede the existing revenue recognition guidance. The new accounting guidance creates a framework by which an entity will allocate the transaction price to separate performance obligations and recognize revenue when each performance obligation is satisfied. Under the new standard, entities will be required to use judgment and make estimates, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price, allocating the transaction price to each separate performance obligation and determining when an entity satisfies its performance obligations. The standard allows for either “full retrospective” adoption, meaning that the standard is applied to all of the periods presented with a cumulative catch-up as of the earliest period presented, or “modified retrospective” adoption, meaning the standard is applied only to the most current period presented in the financial statements with a cumulative catch-up as of the current period. The accounting standard will be effective for reporting periods beginning after December 15, 2016. The Company is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows.

Financial_Instruments

Financial Instruments	6 Months Ended
	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
Financial Instruments	'
	Financial Instruments
	Cash Equivalents
	The Company had $747,008 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 June 30, 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:
		June 30,				December 31,
		2014				2013
	Current	$	—			$	239,388
	Non-current	18,879				—
	Total available-for-sale securities	$	18,879			$	239,388
	The cost, gross unrealized gains, gross unrealized losses and fair value of the Company’s available-for-sale securities were as follows:
			June 30, 2014
			Cost				Gross			Gross			Fair Value
							Unrealized			Unrealized
							Gains			Losses
	Equity securities		$	14,985			$	3,894		$	—		$	18,879
	Total available-for-sale securities		$	14,985			$	3,894		$	—		$	18,879
			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 June 30, 2014 and December 31, 2013, net unrealized gains on the Company's available-for-sale securities of $2,495 and $176, respectively, net of income tax expense of $1,399 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.
	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 and six months ended June 30, 2013.
			Three Months Ended June 30,				Six Months Ended June 30,
			2014				2014
	Proceeds from sales and maturities of securities		$	311,926			$	342,045
	Gross realized gains		1,298				$	1,311
	Gross realized losses		(61		)		$	(99	)

Accounts_Receivable

Accounts Receivable	6 Months Ended
	Jun. 30, 2014
Accounts Receivable, Net [Abstract]	'
Accounts Receivable	'
	Accounts Receivable
	Accounts receivable consist of the following:
		June 30,			December 31,
		2014			2013
	Trade customers	$	445,156		$	410,302
	Affiliates	300			315
	Allowance for doubtful accounts	(12,052		)	(11,741		)
		433,404			398,876
	Federal and state taxes	7,512			20,820
	Other	13,365			8,761
	Accounts receivable, net	$	454,281		$	428,457

Inventories

Inventories	6 Months Ended
	Jun. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories consist of the following:
		June 30,		December 31,
		2014		2013
	Finished products	$	218,817	$	232,658
	Feedstock, additives and chemicals	159,099		180,646
	Materials and supplies	59,603		58,575
	Inventories	$	437,519	$	471,879

Property_Plant_and_Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2014
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment	'
	Property, Plant and Equipment
	As of June 30, 2014, the Company had property, plant and equipment, net totaling $2,217,049. 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 $39,859 and $32,615 is included in cost of sales in the consolidated statements of operations for the three months ended June 30, 2014 and 2013, respectively. Depreciation expense on property, plant and equipment of $77,920 and $63,535 is included in cost of sales in the consolidated statements of operation for the six months ended June 30, 2014 and 2013, respectively.

Other_Assets

Other Assets	6 Months Ended
	Jun. 30, 2014
Other Assets [Abstract]	'
Other Assets	'
	Other Assets
	Amortization expense on intangible and other assets of $9,008 and $7,959 is included in the consolidated statements of operations for the three months ended June 30, 2014 and 2013, respectively. Amortization expense on intangible and other assets of $17,284 and $12,760 is included in the consolidated statements of operations for the six months ended June 30, 2014 and 2013, respectively.
	Goodwill
	Goodwill for the Olefins segment was $29,990 at June 30, 2014 and December 31, 2013. Goodwill for the Vinyls segment was $32,026 at June 30, 2014 and December 31, 2013. There were no changes in the carrying amount of goodwill by operating segments for the six months ended June 30, 2014.
	The annual impairment test for the Olefins segment's recorded goodwill was performed as of October 31, 2013. The annual impairment test for the Vinyls segment's recorded goodwill was performed as of April 30, 2014. The impairment test indicated that the Vinyls segment's goodwill was not impaired. There has been no impairment of the Vinyls segment's goodwill since it was initially recorded.
	Vinyls Segment Goodwill
	The fair value of the pipe and foundation building products business, the reporting unit assessed, was calculated using both a discounted cash flow methodology and a market value methodology. The discounted cash flow projections were based on a 10-year forecast, from 2014 to 2023, to reflect the cyclicality of the North American housing and construction markets as the Company's pipe and foundation building products business is significantly influenced by said markets. The forecast was based on historical results and estimates by management, including their strategic and operational plans, and assumed a gradual increase in financial performance based on a housing market recovery in the United States. The future cash flows were discounted to present value using a discount rate of 8.8%.
	The significant assumptions used in determining the fair value of the reporting unit using the market value methodology include the determination of appropriate market comparables and the estimated multiples of EBITDA a willing buyer is likely to pay.
	Even if the fair value of the reporting unit decreased by 10%, the carrying value of the reporting unit would not exceed its fair value.

LongTerm_Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	Long-Term Debt
	Long-term debt consists of the following:
		June 30,		December 31,
		2014		2013
	3.60% senior notes due 2022	$	249,049	$	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	$	763,938	$	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 June 30, 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 June 30, 2014, the Company had outstanding letters of credit totaling $17,773 and borrowing availability of $382,227 under the revolving credit facility.
	Subsequent to June 30, 2014, the Company entered into a third amendment and restatement to the revolving credit facility. See Note 18 for additional information.

StockBased_Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 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 $2,289 and $1,626 for the three months ended June 30, 2014 and 2013, respectively, and $4,511 and $3,124 for the six months ended June 30, 2014 and 2013, respectively.

Derivative_Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 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 statements of operations for the three and six months ended June 30, 2013. The Company had no derivative instruments that were designated as fair value hedges for the three and six months ended June 30, 2014.
	Gains and losses from changes in the fair value of derivative instruments that are not designated as hedging instruments were included in gross profit in the consolidated statements of operations for the three and six months ended June 30, 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 June 30, 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
			June 30,		December 31,
			2014		2013
	Not designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	$	937	$	296
	Total derivative assets		$	937	$	296
		Derivative Liabilities
		Balance Sheet Location	Fair Value as of
			June 30,		December 31,
			2014		2013
	Not designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	$	924	$	176
	Total derivative liabilities		$	924	$	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 and six months ended June 30, 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 June 30,					Six Months Ended June 30,
	Hedging Relationships	Recognized in
		Income on Derivative	2014		2013			2014			2013
	Commodity forward contracts	Cost of sales	$	—	$	1,533		$	—		$	(110	)
	Hedged Items in Fair Value	Location of Gain (Loss)	Three Months Ended June 30,					Six Months Ended June 30,
	Hedging Relationships	Recognized in
		Income on Hedged Items	2014		2013			2014			2013
	Firm commitment designated	Cost of sales	$	—	$	(1,615	)	$	—		$	(220	)
	as the hedged item
	The impact of derivative instruments that have not been designated as hedges on the Company's consolidated statements of operations were as follows:
	Derivatives Not Designated as	Location of Gain (Loss)	Three Months Ended June 30,					Six Months Ended June 30,
	Hedging Instruments	Recognized in
		Income on Derivative	2014		2013			2014			2013
	Commodity forward contracts	Gross profit	$	240	$	9,382		$	(371	)	$	16,717
	See Note 10 for the fair value of the Company's derivative instruments.

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 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:
		30-Jun-14
		Level 1		Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	430	$	507		$	937
	Risk management liabilities - Commodity forward contracts	—		(924		)	(924		)
	Available-for-sale marketable securities	18,879		—			18,879
		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 six months ended June 30, 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.
		30-Jun-14					December 31, 2013
		Carrying		Fair			Carrying			Fair
		Value		Value			Value			Value
	3.60% senior notes due 2022	$	249,049	$	250,510		$	248,990		$	236,905
	6 ½% senior notes due 2029	100,000		115,750			100,000			109,490
	6 ¾% senior notes due 2032	250,000		278,525			250,000			265,148
	6 ½% GO Zone Senior Notes Due 2035	89,000		104,670			89,000			94,606
	6 ½% IKE Zone Senior Notes Due 2035	65,000		76,445			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	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The effective income tax rate was 34.9% for the six months ended June 30, 2014. The effective income tax rate for the 2014 period was below the U.S. federal statutory rate of 35.0% primarily due to state tax credits and the domestic manufacturing deduction, mostly offset by state income taxes. The effective income tax rate was 36.1% for the six months ended June 30, 2013. The effective income tax rate for the 2013 period was above the U.S. federal statutory rate of 35.0% primarily due to state income taxes, partially offset by the domestic manufacturing deduction.
	There was no material change to the total gross unrecognized tax benefits for the six months ended June 30, 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 June 30, 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	6 Months Ended
	Jun. 30, 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 June 30,						Six Months Ended June 30,
			2014			2013			2014			2013
	Net income		$	169,443		$	145,816		$	327,475		$	269,163
	Less:
	Net income attributable to participating securities		(360		)	(512		)	(746		)	(1,091		)
	Net income attributable to common shareholders		$	169,083		$	145,304		$	326,729		$	268,072
	The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:
			Three Months Ended June 30,						Six Months Ended June 30,
			2014			2013			2014			2013
	Weighted average common shares—basic (1)		133,223,705			133,259,218			133,148,398			133,255,322
	Plus incremental shares from:
	Assumed exercise of options (1)		544,185			531,972			542,438			549,224
	Weighted average common shares—diluted (1)		133,767,890			133,791,190			133,690,836			133,804,546
	Earnings per share: (1)
	Basic		$	1.27		$	1.09		$	2.45		$	2.01
	Diluted		$	1.26		$	1.09		$	2.44		$	2.01
	_____________
	-1	Share amounts and per share data for the three and six months ended June 30, 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 134,938 and 142,912 shares of common stock for the three months ended June 30, 2014 and 2013, respectively, and 102,480 and 108,000 shares of common stock for the six months ended June 30, 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	6 Months Ended
	Jun. 30, 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 June 30,										Six Months Ended June 30,
		Pension						Post-retirement				Pension						Post-retirement
								Healthcare										Healthcare
		2014			2013			2014		2013		2014			2013			2014		2013
	Service cost	$	84		$	275		$	5	$	2	$	167		$	539		$	11	$	5
	Interest cost	576			515			181		147		1,170			1,016			362		294
	Expected return on	(777		)	(713		)	—		—		(1,586		)	(1,427		)	—		—
	plan assets
	Amortization of prior	74			74			13		21		148			148			25		42
	service cost
	Amortization of net loss	70			510			69		90		134			940			138		179
	Net periodic benefit cost	$	27		$	661		$	268	$	260	$	33		$	1,216		$	536	$	520
	The Company contributed $965 and $388 to the Salaried pension plan in the first six months of 2014 and 2013, respectively, and contributed $580 and $350 to the Wage pension plan in the first six months of 2014 and 2013, respectively. The Company expects to make additional contributions of $1,812 to the Salaried pension plan and $626 to the Wage pension plan during the fiscal year ending December 31, 2014.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Accumulated Other Comprehensive Income	'
	Accumulated Other Comprehensive Loss
	Changes in accumulated other comprehensive income (loss) by component for the six months ended June 30, 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		(20		)		(90		)		3,096				2,986
	reclassifications
	Amounts reclassified from accumulated other		275				—				(777		)		(502		)
	comprehensive loss
	Net other comprehensive income (loss) for the period		255				(90		)		2,319				2,484
	Balances at June 30, 2014		$	(6,441	)		$	3,814			$	2,495			$	(132	)
			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		(301		)		(1,390		)		(1,691		)
	Amounts reclassified from accumulated other comprehensive loss		805				—				805
	Net other comprehensive income (loss) for the period		504				(1,390		)		(886		)
	Balances at June 30, 2013		$	(15,847	)		$	4,121			$	(11,726	)
	The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three and six months ended June 30, 2014 and 2013:
	Details about Accumulated Other Comprehensive		Location of Reclassification		Three Months Ended June 30,								Six Months Ended June 30,
	Income (Loss) Components		(Income (Expense)) in
			Consolidated Statements
			of Operations		2014				2013				2014				2013
	Amortization of pension and
	other post-retirement items
	Prior service costs		-1		$	(87	)		$	(95	)		$	(173	)		$	(190	)
	Net loss		-1		(139		)		(600		)		(272		)		(1,119		)
					(226		)		(695		)		(445		)		(1,309		)
			Provision for income		86				268				170				504
			taxes
					(140		)		(427		)		(275		)		(805		)
	Net unrealized gains on
	available-for-sale
	investments
	Realized gain on		Other income, net		1,237				—				1,212				—
	available-for-sale
	investments
			Provision for income		(444		)		—				(435		)		—
			taxes
					793				—				$	777			$	—
	Total reclassifications for				$	653			$	(427	)		$	502			$	(805	)
	the period
	_____________
	-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	6 Months Ended
	Jun. 30, 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.

Share_Capital

Share Capital	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Share Capital	'
	Share Capital
	Common Stock
	On May 16, 2014, the stockholders of the Company approved an amendment to the Company's Amended and Restated Certificate of Incorporation to increase the Company's authorized shares of common stock from 150,000,000 shares to 300,000,000 shares, par value $0.01 per share. The Company is now authorized to issue 300,000,000 shares of common stock, par value $0.01 per share, of which 134,681,372 and 134,580,208 shares (on a post-split basis) were issued as of June 30, 2014 and December 31, 2013, respectively. Each share of common stock entitles the holder to one vote on all matters on which holders are permitted to vote, including the election of directors.
	Stock Repurchase Program
	In August 2011, the Company's Board of Directors authorized a stock repurchase program of the Company’s common stock totaling $100,000 (the "2011 Program"). Purchases under the 2011 Program began in September 2011. As of June 30, 2014 and December 31, 2013, the Company had repurchased 1,252,922 shares of its common stock (on a post-split basis) under this program. Shares repurchased under the 2011 Program are held by the Company as treasury stock and may be used for general corporate purposes, including for the 2013 Omnibus Incentive Plan. Beginning in May 2014, the Company began issuing treasury shares to employees and nonemployee directors for options exercised and for the release of restricted stock units. The cost of treasury shares issued was determined using the specific identification method.

Segment_Information

Segment Information	6 Months Ended
	Jun. 30, 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 June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Net external sales
	Olefins
	Polyethylene	$	475,503		$	413,693		$	962,647		$	834,461
	Styrene, feedstock and other	223,550			209,648			459,204			371,725
	Total Olefins	699,053			623,341			1,421,851			1,206,186
	Vinyls
	PVC, caustic soda and other	168,762			205,104			359,289			400,350
	Building products	130,761			110,602			245,112			197,158
	Total Vinyls	299,523			315,706			604,401			597,508
		$	998,576		$	939,047		$	2,026,252		$	1,803,694
	Intersegment sales
	Olefins	$	34,782		$	74,870		$	91,635		$	145,153
	Vinyls	331			444			674			708
		$	35,113		$	75,314		$	92,309		$	145,861
	Income (loss) from operations
	Olefins	$	238,657		$	187,661		$	510,990		$	348,719
	Vinyls	38,129			52,906			17,015			96,569
	Corporate and other	(9,998		)	(5,340		)	(13,162		)	(16,006		)
		$	266,788		$	235,227		$	514,843		$	429,282
	Depreciation and amortization
	Olefins	$	26,721		$	26,554		$	53,368		$	49,900
	Vinyls	21,623			13,534			40,791			25,418
	Corporate and other	158			122			315			248
		$	48,502		$	40,210		$	94,474		$	75,566
	Other income (expense), net
	Olefins	$	1,199		$	1,151		$	2,653		$	5,162
	Vinyls	(213		)	(520		)	(247		)	(946		)
	Corporate and other	3,615			(726		)	4,704			(792		)
		$	4,601		$	(95	)	$	7,110		$	3,424
	Provision for (benefit from) income taxes
	Olefins	$	83,502		$	70,140		$	177,052		$	125,617
	Vinyls	10,430			19,690			360			33,410
	Corporate and other	(1,525		)	(5,857		)	(1,630		)	(7,108		)
		$	92,407		$	83,973		$	175,782		$	151,919
	Capital expenditures
	Olefins	$	43,448		$	28,040		$	72,522		$	78,080
	Vinyls	62,262			118,983			143,382			219,300
	Corporate and other	461			66			1,008			493
		$	106,171		$	147,089		$	216,912		$	297,873
	A reconciliation of total segment income from operations to consolidated income before income taxes is as follows:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Income from operations	$	266,788		$	235,227		$	514,843		$	429,282
	Interest expense	(9,539		)	(5,343		)	(18,696		)	(11,624		)
	Other income (expense), net	4,601			(95		)	7,110			3,424
	Income before income taxes	$	261,850		$	229,789		$	503,257		$	421,082
		June 30,			December 31,
		2014			2013
	Total assets
	Olefins	$	1,607,210		$	1,557,510
	Vinyls	1,808,849			1,740,595
	Corporate and other	953,310			762,804
		$	4,369,369		$	4,060,909

Subsequent_Events

Subsequent Events	6 Months Ended
	Jun. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	Initial Public Offering of WLKP
	In March 2014, the Company formed Westlake Chemical Partners LP ("WLKP") to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, WLKP closed its initial public offering of 12,937,500 common units at a price of $24.00 per unit, which included 1,687,500 units purchased by the underwriters through an over-allotment option. Net proceeds to WLKP from the sale of the units was approximately $286,263, net of underwriting discounts, structuring fees and estimated offering expenses of approximately $24,237. At the consummation of this offering, WLKP's assets consist of a 10.6% limited partner interest in Westlake Chemical OpCo LP ("OpCo"), as well as the general partner interest in OpCo. The Company retained an 89.4% limited partner interest in OpCo and a significant interest in WLKP. OpCo used the net proceeds from the purchase of its limited partner interest to establish a cash reserve of $55,400 for turnaround expenditures, to reimburse approximately $155,700 for capital expenditures incurred by the Company with respect to certain of the assets contributed to OpCo and to repay intercompany debt to the Company of approximately $75,144. The initial public offering represented the sale of a 47.8% interest in WLKP.
	Amendment and Restatement of the Revolving Credit Facility
	In July 2014, the Company entered into a third amendment and restatement to the revolving credit facility. The amendment and restatement extended the scheduled maturity date of the facility from September 16, 2016 to July 17, 2019, reduced the interest rate and facility fee payable under the facility and, among other things, amended the covenants restricting the Company’s ability to make distributions and acquisitions and investments.
	Acquisition of Vinnolit Holdings GmbH Group
	In May 2014, the Company announced that it had entered into a definitive agreement to acquire German-based Vinnolit Holdings GmbH and its subsidiary companies ("Vinnolit") for approximately €490,000 from several entities associated with Advent International Corporation. Vinnolit is an integrated global leader in specialty PVC resins, with a combined annual capacity of 1.7 billion pounds of PVC, including specialty paste and suspension grades, 1.5 billion pounds of vinyl chloride monomer ("VCM") and 1.0 billion pounds of caustic soda. This transaction closed on July 31, 2014.
	General
	Subsequent events were evaluated through the date on which the financial statements were issued.

Guarantor_Disclosures

Guarantor Disclosures	6 Months Ended
	Jun. 30, 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 June 30, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Balance Sheet
	Current assets
	Cash and cash equivalents	$	833,650		$	8,819		$	33,598		$	—		$	876,067
	Marketable securities	—			—			—			—			—
	Accounts receivable, net	12,499			995,379			4,145			(557,742		)	454,281
	Inventories	—			419,659			17,860			—			437,519
	Prepaid expenses and other	95			18,169			2,204			—			20,468
	current assets
	Deferred income taxes	441			33,422			305			—			34,168
	Total current assets	846,685			1,475,448			58,112			(557,742		)	1,822,503
	Property, plant and equipment, net	—			2,210,754			6,295			—			2,217,049
	Equity investments	3,148,210			103,650			30,186			(3,213,179		)	68,867
	Other assets, net	32,535			231,938			1,249			(4,772		)	260,950
	Total assets	$	4,027,430		$	4,021,790		$	95,842		$	(3,775,693	)	$	4,369,369
	Current liabilities
	Accounts payable	$	533,491		$	204,830		$	14,870		$	(533,591	)	$	219,600
	Accrued liabilities	12,817			177,648			1,015			(24,151		)	167,329
	Total current liabilities	546,308			382,478			15,885			(557,742		)	386,929
	Long-term debt	753,049			10,889			—			—			763,938
	Deferred income taxes	—			462,930			632			(4,772		)	458,790
	Other liabilities	—			31,599			40			—			31,639
	Stockholders' equity	2,728,073			3,133,894			79,285			(3,213,179		)	2,728,073
	Total liabilities and	$	4,027,430		$	4,021,790		$	95,842		$	(3,775,693	)	$	4,369,369
	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 June 30, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
Net sales	$	—		$	988,944		$	11,753		$	(2,121	)	$	998,576
Cost of sales	—			683,790			10,936			(2,121		)	692,605
Gross profit	—			305,154			817			—			305,971
Selling, general and administrative	529			37,231			1,423			—			39,183
expenses
(Loss) income from operations	(529		)	267,923			(606		)	—			266,788
Interest expense	(9,535		)	(4		)	—			—			(9,539		)
Other income (expense), net	7,137			(1,743		)	(793		)	—			4,601
(Loss) income before income taxes	(2,927		)	266,176			(1,399		)	—			261,850
(Benefit from) provision for income taxes	(1,039		)	93,595			(149		)	—			92,407
Equity in net income of subsidiaries	171,331			—			—			(171,331		)	—
Net income (loss)	$	169,443		$	172,581		$	(1,250	)	$	(171,331	)	$	169,443
Comprehensive income (loss)	$	171,093		$	172,701		$	(442	)	$	(172,259	)	$	171,093
Condensed Consolidating Financial Information for the Three Months Ended June 30, 2013
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Operations
Net sales	$	—		$	928,782		$	13,684		$	(3,419	)	$	939,047
Cost of sales	—			657,457			11,522			(3,419		)	665,560
Gross profit	—			271,325			2,162			—			273,487
Selling, general and administrative	552			36,055			1,653			—			38,260
expenses
(Loss) income from operations	(552		)	235,270			509			—			235,227
Interest expense	(5,332		)	(11		)	—			—			(5,343		)
Other (expense) income, net	(404		)	1,638			(1,329		)	—			(95		)
(Loss) income before income taxes	(6,288		)	236,897			(820		)	—			229,789
(Benefit from) provision for income taxes	(2,258		)	86,401			(170		)	—			83,973
Equity in net income of subsidiaries	149,846			—			—			(149,846		)	—
Net income (loss)	$	145,816		$	150,496		$	(650	)	$	(149,846	)	$	145,816
Comprehensive income (loss)	$	145,122		$	150,622		$	(1,470	)	$	(149,152	)	$	145,122
Condensed Consolidating Financial Information for the Six Months Ended June 30, 2014
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Operations
Net sales	$	—		$	2,009,373		$	20,870		$	(3,991	)	$	2,026,252
Cost of sales	—			1,418,140			19,122			(3,991		)	1,433,271
Gross profit	—			591,233			1,748			—			592,981
Selling, general and administrative	1,075			74,294			2,769			—			78,138
expenses
(Loss) income from operations	(1,075		)	516,939			(1,021		)	—			514,843
Interest expense	(18,690		)	(6		)	—			—			(18,696		)
Other income (expense), net	12,351			(3,834		)	(1,407		)	—			7,110
(Loss) income before income taxes	(7,414		)	513,099			(2,428		)	—			503,257
(Benefit from) provision for income taxes	(2,597		)	178,705			(326		)	—			175,782
Equity in net income of subsidiaries	332,292			—			—			(332,292		)	—
Net income (loss)	$	327,475		$	334,394		$	(2,102	)	$	(332,292	)	$	327,475
Comprehensive income (loss)	$	329,959		$	334,649		$	(2,192	)	$	(332,457	)	$	329,959
Condensed Consolidating Financial Information for the Six Months Ended June 30, 2013
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Operations
Net sales	$	—		$	1,784,867		$	24,224		$	(5,397	)	$	1,803,694
Cost of sales	—			1,286,743			21,052			(5,397		)	1,302,398
Gross profit	—			498,124			3,172			—			501,296
Selling, general and administrative	1,062			67,764			3,188			—			72,014
expenses
(Loss) income from operations	(1,062		)	430,360			(16		)	—			429,282
Interest expense	(11,590		)	(34		)	—			—			(11,624		)
Other income (expense), net	3,905			1,348			(1,829		)	—			3,424
(Loss) income before income taxes	(8,747		)	431,674			(1,845		)	—			421,082
(Benefit from) provision for income taxes	(3,132		)	155,452			(401		)	—			151,919
Equity in net income of subsidiaries	274,778			—			—			(274,778		)	—
Net income (loss)	$	269,163		$	276,222		$	(1,444	)	$	(274,778	)	$	269,163
Comprehensive income (loss)	$	268,277		$	276,726		$	(2,834	)	$	(273,892	)	$	268,277
Condensed Consolidating Financial Information for the Six Months Ended June 30, 2014
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	327,475		$	334,394		$	(2,102	)	$	(332,292	)	$	327,475
Adjustments to reconcile net income
(loss) to net cash (used for) provided
by operating activities
Depreciation and amortization	730			93,403			1,071			—			95,204
Deferred income taxes	(292		)	19,744			(93		)	—			19,359
Net changes in working capital	(336,669		)	(3,271		)	(2,148		)	332,292			(9,796		)
and other
Net cash (used for) provided by	(8,756		)	444,270			(3,272		)	—			432,242
operating activities
Cash flows from investing activities
Additions to property, plant and	—			(216,529		)	(383		)	—			(216,912		)
equipment
Proceeds from disposition of assets	—			12			1			—			13
Proceeds from sales and maturities of	342,045			—			—			—			342,045
securities
Purchase of securities	(117,332		)	—			—			—			(117,332		)
Settlements of derivative instruments	—			(290		)	—			—			(290		)
Net cash provided by (used for)	224,713			(216,807		)	(382		)	—			7,524
investing activities
Cash flows from financing activities
Intercompany financing	221,745			(224,871		)	3,126			—			—
Dividends paid	(33,623		)	—			—			—			(33,623		)
Proceeds from exercise of stock options	4,187			—			—			—			4,187
Windfall tax benefits from share-based	4,436			—			—			—			4,436
payment arrangements
Net cash provided by (used for)	196,745			(224,871		)	3,126			—			(25,000		)
financing activities
Net increase (decrease) in cash and	412,702			2,592			(528		)	—			414,766
cash equivalents
Cash and cash equivalents at beginning	420,948			6,227			34,126			—			461,301
of period
Cash and cash equivalents at end of period	$	833,650		$	8,819		$	33,598		$	—		$	876,067
Condensed Consolidating Financial Information for the Six Months Ended June 30, 2013
	Westlake			Guarantor			Non-			Eliminations			Consolidated
	Chemical			Subsidiaries			Guarantor
	Corporation						Subsidiaries
Statement of Cash Flows
Cash flows from operating activities
Net income (loss)	$	269,163		$	276,222		$	(1,444	)	$	(274,778	)	$	269,163
Adjustments to reconcile net income
(loss) to net cash (used for) provided
by operating activities
Depreciation and amortization	730			74,298			1,267			—			76,295
Deferred income taxes	(1,230		)	61,610			45			—			60,425
Net changes in working capital	(279,039		)	(153,604		)	7,462			274,778			(150,403		)
and other
Net cash (used for) provided by	(10,376		)	258,526			7,330			—			255,480
operating activities
Cash flows from investing activities
Acquisition of business	—			(178,309		)	—			—			(178,309		)
Additions to equity investments	—			(6,113		)	—			—			(6,113		)
Additions to property, plant and	—			(295,859		)	(2,014		)	—			(297,873		)
equipment
Construction of assets pending	—			(136		)	—			—			(136		)
sale-leaseback
Proceeds from disposition of assets	—			2			60			—			62
Proceeds from repayment of loan	—			—			167			—			167
to affiliate
Proceeds from sales and maturities of	209,785			—			—			—			209,785
securities
Purchase of securities	(114,881		)	—			—			—			(114,881		)
Settlements of derivative instruments	—			(1,588		)	—			—			(1,588		)
Net cash provided by (used for)	94,904			(482,003		)	(1,787		)	—			(388,886		)
investing activities
Cash flows from financing activities
Intercompany financing	(214,927		)	219,968			(5,041		)	—			—
Dividends paid	(25,120		)	—			—			—			(25,120		)
Proceeds from exercise of stock options	2,656			—			—			—			2,656
Repurchase of common stock for treasury	(13,283		)	—			—			—			(13,283		)
Windfall tax benefits from share-based	4,576			—			—			—			4,576
payment arrangements
Net cash (used for) provided by	(246,098		)	219,968			(5,041		)	—			(31,171		)
financing activities
Net (decrease) increase in cash and	(161,570		)	(3,509		)	502			—			(164,577		)
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	$	592,311		$	3,464		$	29,726		$	—		$	625,501

Basis_of_Financial_Statements_

Basis of Financial Statements (Policies)	6 Months Ended
	Jun. 30, 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 June 30, 2014, its results of operations for the three and six months ended June 30, 2014 and 2013 and the changes in its cash position for the six months ended June 30, 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

Financial_Instruments_Tables

Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2014													Jun. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'													'
Marketable Securities	'													'
														Investments in available-for-sale securities were classified as follows:
															June 30,		December 31,
															2014		2013
														Current	$	—	$	239,388
														Non-current	18,879		—
														Total available-for-sale securities	$	18,879	$	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:
			June 30, 2014
			Cost			Gross			Gross			Fair Value
						Unrealized			Unrealized
						Gains			Losses
	Equity securities		$	14,985		$	3,894		$	—		$	18,879
	Total available-for-sale securities		$	14,985		$	3,894		$	—		$	18,879
			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 June 30,			Six Months Ended June 30,
			2014			2014
	Proceeds from sales and maturities of securities		$	311,926		$	342,045
	Gross realized gains		1,298			$	1,311
	Gross realized losses		(61		)	$	(99	)

Accounts_Receivable_Tables

Accounts Receivable (Tables)	6 Months Ended
	Jun. 30, 2014
Accounts Receivable, Net [Abstract]	'
Schedule Of Accounts Receivable	'
	Accounts receivable consist of the following:
		June 30,			December 31,
		2014			2013
	Trade customers	$	445,156		$	410,302
	Affiliates	300			315
	Allowance for doubtful accounts	(12,052		)	(11,741		)
		433,404			398,876
	Federal and state taxes	7,512			20,820
	Other	13,365			8,761
	Accounts receivable, net	$	454,281		$	428,457

Inventories_Tables

Inventories (Tables)	6 Months Ended
	Jun. 30, 2014
Inventory Disclosure [Abstract]	'
Schedule Of Inventory	'
	Inventories consist of the following:
		June 30,		December 31,
		2014		2013
	Finished products	$	218,817	$	232,658
	Feedstock, additives and chemicals	159,099		180,646
	Materials and supplies	59,603		58,575
	Inventories	$	437,519	$	471,879

LongTerm_Debt_Tables

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Schedule Of Long-Term Debt	'
	Long-term debt consists of the following:
		June 30,		December 31,
		2014		2013
	3.60% senior notes due 2022	$	249,049	$	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	$	763,938	$	763,879

Derivative_Instruments_Tables

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 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
			June 30,		December 31,
			2014		2013
	Not designated as hedging instruments
	Commodity forward contracts	Accounts receivable, net	$	937	$	296
	Total derivative assets		$	937	$	296
		Derivative Liabilities
		Balance Sheet Location	Fair Value as of
			June 30,		December 31,
			2014		2013
	Not designated as hedging instruments
	Commodity forward contracts	Accrued liabilities	$	924	$	176
	Total derivative liabilities		$	924	$	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 and six months ended June 30, 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 June 30,					Six Months Ended June 30,
	Hedging Relationships	Recognized in
		Income on Derivative	2014		2013			2014			2013
	Commodity forward contracts	Cost of sales	$	—	$	1,533		$	—		$	(110	)
	Hedged Items in Fair Value	Location of Gain (Loss)	Three Months Ended June 30,					Six Months Ended June 30,
	Hedging Relationships	Recognized in
		Income on Hedged Items	2014		2013			2014			2013
	Firm commitment designated	Cost of sales	$	—	$	(1,615	)	$	—		$	(220	)
	as the hedged item
Impact of Derivative Instruments Not Designated as Fair Value Hedges	'
	The impact of derivative instruments that have not been designated as hedges on the Company's consolidated statements of operations were as follows:
	Derivatives Not Designated as	Location of Gain (Loss)	Three Months Ended June 30,					Six Months Ended June 30,
	Hedging Instruments	Recognized in
		Income on Derivative	2014		2013			2014			2013
	Commodity forward contracts	Gross profit	$	240	$	9,382		$	(371	)	$	16,717

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 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:
		30-Jun-14
		Level 1		Level 2			Total
	Derivative instruments
	Risk management assets - Commodity forward contracts	$	430	$	507		$	937
	Risk management liabilities - Commodity forward contracts	—		(924		)	(924		)
	Available-for-sale marketable securities	18,879		—			18,879
		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.
		30-Jun-14					December 31, 2013
		Carrying		Fair			Carrying			Fair
		Value		Value			Value			Value
	3.60% senior notes due 2022	$	249,049	$	250,510		$	248,990		$	236,905
	6 ½% senior notes due 2029	100,000		115,750			100,000			109,490
	6 ¾% senior notes due 2032	250,000		278,525			250,000			265,148
	6 ½% GO Zone Senior Notes Due 2035	89,000		104,670			89,000			94,606
	6 ½% IKE Zone Senior Notes Due 2035	65,000		76,445			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)	6 Months Ended
	Jun. 30, 2014
Earnings Per Share [Abstract]	'
Schedule Of Net Income Attributable To Common Stockholders	'
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Net income	$	169,443		$	145,816		$	327,475		$	269,163
	Less:
	Net income attributable to participating securities	(360		)	(512		)	(746		)	(1,091		)
	Net income attributable to common shareholders	$	169,083		$	145,304		$	326,729		$	268,072
Reconciliation Of Denominator For Basic And Diluted Earnings Per Share	'
	The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Weighted average common shares—basic (1)	133,223,705			133,259,218			133,148,398			133,255,322
	Plus incremental shares from:
	Assumed exercise of options (1)	544,185			531,972			542,438			549,224
	Weighted average common shares—diluted (1)	133,767,890			133,791,190			133,690,836			133,804,546
	Earnings per share: (1)
	Basic	$	1.27		$	1.09		$	2.45		$	2.01
	Diluted	$	1.26		$	1.09		$	2.44		$	2.01

Pension_and_PostRetirement_Ben1

Pension and Post-Retirement Benefit Costs (Tables)	6 Months Ended
	Jun. 30, 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 June 30,										Six Months Ended June 30,
		Pension						Post-retirement				Pension						Post-retirement
								Healthcare										Healthcare
		2014			2013			2014		2013		2014			2013			2014		2013
	Service cost	$	84		$	275		$	5	$	2	$	167		$	539		$	11	$	5
	Interest cost	576			515			181		147		1,170			1,016			362		294
	Expected return on	(777		)	(713		)	—		—		(1,586		)	(1,427		)	—		—
	plan assets
	Amortization of prior	74			74			13		21		148			148			25		42
	service cost
	Amortization of net loss	70			510			69		90		134			940			138		179
	Net periodic benefit cost	$	27		$	661		$	268	$	260	$	33		$	1,216		$	536	$	520

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	'
	Changes in accumulated other comprehensive income (loss) by component for the six months ended June 30, 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		(20		)		(90		)		3,096				2,986
	reclassifications
	Amounts reclassified from accumulated other		275				—				(777		)		(502		)
	comprehensive loss
	Net other comprehensive income (loss) for the period		255				(90		)		2,319				2,484
	Balances at June 30, 2014		$	(6,441	)		$	3,814			$	2,495			$	(132	)
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	'
	The following table provides the details of the amounts reclassified from accumulated other comprehensive income (loss) into net income in the consolidated statements of operations for the three and six months ended June 30, 2014 and 2013:
	Details about Accumulated Other Comprehensive		Location of Reclassification		Three Months Ended June 30,								Six Months Ended June 30,
	Income (Loss) Components		(Income (Expense)) in
			Consolidated Statements
			of Operations		2014				2013				2014				2013
	Amortization of pension and
	other post-retirement items
	Prior service costs		-1		$	(87	)		$	(95	)		$	(173	)		$	(190	)
	Net loss		-1		(139		)		(600		)		(272		)		(1,119		)
					(226		)		(695		)		(445		)		(1,309		)
			Provision for income		86				268				170				504
			taxes
					(140		)		(427		)		(275		)		(805		)
	Net unrealized gains on
	available-for-sale
	investments
	Realized gain on		Other income, net		1,237				—				1,212				—
	available-for-sale
	investments
			Provision for income		(444		)		—				(435		)		—
			taxes
					793				—				$	777			$	—
	Total reclassifications for				$	653			$	(427	)		$	502			$	(805	)
	the period
	_____________
	-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)	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Segment Reporting Information	'
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Net external sales
	Olefins
	Polyethylene	$	475,503		$	413,693		$	962,647		$	834,461
	Styrene, feedstock and other	223,550			209,648			459,204			371,725
	Total Olefins	699,053			623,341			1,421,851			1,206,186
	Vinyls
	PVC, caustic soda and other	168,762			205,104			359,289			400,350
	Building products	130,761			110,602			245,112			197,158
	Total Vinyls	299,523			315,706			604,401			597,508
		$	998,576		$	939,047		$	2,026,252		$	1,803,694
	Intersegment sales
	Olefins	$	34,782		$	74,870		$	91,635		$	145,153
	Vinyls	331			444			674			708
		$	35,113		$	75,314		$	92,309		$	145,861
	Income (loss) from operations
	Olefins	$	238,657		$	187,661		$	510,990		$	348,719
	Vinyls	38,129			52,906			17,015			96,569
	Corporate and other	(9,998		)	(5,340		)	(13,162		)	(16,006		)
		$	266,788		$	235,227		$	514,843		$	429,282
	Depreciation and amortization
	Olefins	$	26,721		$	26,554		$	53,368		$	49,900
	Vinyls	21,623			13,534			40,791			25,418
	Corporate and other	158			122			315			248
		$	48,502		$	40,210		$	94,474		$	75,566
	Other income (expense), net
	Olefins	$	1,199		$	1,151		$	2,653		$	5,162
	Vinyls	(213		)	(520		)	(247		)	(946		)
	Corporate and other	3,615			(726		)	4,704			(792		)
		$	4,601		$	(95	)	$	7,110		$	3,424
	Provision for (benefit from) income taxes
	Olefins	$	83,502		$	70,140		$	177,052		$	125,617
	Vinyls	10,430			19,690			360			33,410
	Corporate and other	(1,525		)	(5,857		)	(1,630		)	(7,108		)
		$	92,407		$	83,973		$	175,782		$	151,919
	Capital expenditures
	Olefins	$	43,448		$	28,040		$	72,522		$	78,080
	Vinyls	62,262			118,983			143,382			219,300
	Corporate and other	461			66			1,008			493
		$	106,171		$	147,089		$	216,912		$	297,873
Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes	'
	A reconciliation of total segment income from operations to consolidated income before income taxes is as follows:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Income from operations	$	266,788		$	235,227		$	514,843		$	429,282
	Interest expense	(9,539		)	(5,343		)	(18,696		)	(11,624		)
	Other income (expense), net	4,601			(95		)	7,110			3,424
	Income before income taxes	$	261,850		$	229,789		$	503,257		$	421,082
Total Assets	'
		June 30,			December 31,
		2014			2013
	Total assets
	Olefins	$	1,607,210		$	1,557,510
	Vinyls	1,808,849			1,740,595
	Corporate and other	953,310			762,804
		$	4,369,369		$	4,060,909

Guarantor_Disclosures_Tables

Guarantor Disclosures (Tables)	6 Months Ended
	Jun. 30, 2014
Guarantees [Abstract]	'
Condensed Consolidating Financial Information Balance Sheet	'
	Condensed Consolidating Financial Information as of June 30, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Balance Sheet
	Current assets
	Cash and cash equivalents	$	833,650		$	8,819		$	33,598		$	—		$	876,067
	Marketable securities	—			—			—			—			—
	Accounts receivable, net	12,499			995,379			4,145			(557,742		)	454,281
	Inventories	—			419,659			17,860			—			437,519
	Prepaid expenses and other	95			18,169			2,204			—			20,468
	current assets
	Deferred income taxes	441			33,422			305			—			34,168
	Total current assets	846,685			1,475,448			58,112			(557,742		)	1,822,503
	Property, plant and equipment, net	—			2,210,754			6,295			—			2,217,049
	Equity investments	3,148,210			103,650			30,186			(3,213,179		)	68,867
	Other assets, net	32,535			231,938			1,249			(4,772		)	260,950
	Total assets	$	4,027,430		$	4,021,790		$	95,842		$	(3,775,693	)	$	4,369,369
	Current liabilities
	Accounts payable	$	533,491		$	204,830		$	14,870		$	(533,591	)	$	219,600
	Accrued liabilities	12,817			177,648			1,015			(24,151		)	167,329
	Total current liabilities	546,308			382,478			15,885			(557,742		)	386,929
	Long-term debt	753,049			10,889			—			—			763,938
	Deferred income taxes	—			462,930			632			(4,772		)	458,790
	Other liabilities	—			31,599			40			—			31,639
	Stockholders' equity	2,728,073			3,133,894			79,285			(3,213,179		)	2,728,073
	Total liabilities and	$	4,027,430		$	4,021,790		$	95,842		$	(3,775,693	)	$	4,369,369
	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 June 30, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
	Net sales	$	—		$	988,944		$	11,753		$	(2,121	)	$	998,576
	Cost of sales	—			683,790			10,936			(2,121		)	692,605
	Gross profit	—			305,154			817			—			305,971
	Selling, general and administrative	529			37,231			1,423			—			39,183
	expenses
	(Loss) income from operations	(529		)	267,923			(606		)	—			266,788
	Interest expense	(9,535		)	(4		)	—			—			(9,539		)
	Other income (expense), net	7,137			(1,743		)	(793		)	—			4,601
	(Loss) income before income taxes	(2,927		)	266,176			(1,399		)	—			261,850
	(Benefit from) provision for income taxes	(1,039		)	93,595			(149		)	—			92,407
	Equity in net income of subsidiaries	171,331			—			—			(171,331		)	—
	Net income (loss)	$	169,443		$	172,581		$	(1,250	)	$	(171,331	)	$	169,443
	Comprehensive income (loss)	$	171,093		$	172,701		$	(442	)	$	(172,259	)	$	171,093
	Condensed Consolidating Financial Information for the Three Months Ended June 30, 2013
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
	Net sales	$	—		$	928,782		$	13,684		$	(3,419	)	$	939,047
	Cost of sales	—			657,457			11,522			(3,419		)	665,560
	Gross profit	—			271,325			2,162			—			273,487
	Selling, general and administrative	552			36,055			1,653			—			38,260
	expenses
	(Loss) income from operations	(552		)	235,270			509			—			235,227
	Interest expense	(5,332		)	(11		)	—			—			(5,343		)
	Other (expense) income, net	(404		)	1,638			(1,329		)	—			(95		)
	(Loss) income before income taxes	(6,288		)	236,897			(820		)	—			229,789
	(Benefit from) provision for income taxes	(2,258		)	86,401			(170		)	—			83,973
	Equity in net income of subsidiaries	149,846			—			—			(149,846		)	—
	Net income (loss)	$	145,816		$	150,496		$	(650	)	$	(149,846	)	$	145,816
	Comprehensive income (loss)	$	145,122		$	150,622		$	(1,470	)	$	(149,152	)	$	145,122
	Condensed Consolidating Financial Information for the Six Months Ended June 30, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
	Net sales	$	—		$	2,009,373		$	20,870		$	(3,991	)	$	2,026,252
	Cost of sales	—			1,418,140			19,122			(3,991		)	1,433,271
	Gross profit	—			591,233			1,748			—			592,981
	Selling, general and administrative	1,075			74,294			2,769			—			78,138
	expenses
	(Loss) income from operations	(1,075		)	516,939			(1,021		)	—			514,843
	Interest expense	(18,690		)	(6		)	—			—			(18,696		)
	Other income (expense), net	12,351			(3,834		)	(1,407		)	—			7,110
	(Loss) income before income taxes	(7,414		)	513,099			(2,428		)	—			503,257
	(Benefit from) provision for income taxes	(2,597		)	178,705			(326		)	—			175,782
	Equity in net income of subsidiaries	332,292			—			—			(332,292		)	—
	Net income (loss)	$	327,475		$	334,394		$	(2,102	)	$	(332,292	)	$	327,475
	Comprehensive income (loss)	$	329,959		$	334,649		$	(2,192	)	$	(332,457	)	$	329,959
	Condensed Consolidating Financial Information for the Six Months Ended June 30, 2013
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Operations
	Net sales	$	—		$	1,784,867		$	24,224		$	(5,397	)	$	1,803,694
	Cost of sales	—			1,286,743			21,052			(5,397		)	1,302,398
	Gross profit	—			498,124			3,172			—			501,296
	Selling, general and administrative	1,062			67,764			3,188			—			72,014
expenses
(Loss) income from operations	(1,062		)	430,360			(16		)	—			429,282
Interest expense	(11,590		)	(34		)	—			—			(11,624		)
Other income (expense), net	3,905			1,348			(1,829		)	—			3,424
(Loss) income before income taxes	(8,747		)	431,674			(1,845		)	—			421,082
(Benefit from) provision for income taxes	(3,132		)	155,452			(401		)	—			151,919
Equity in net income of subsidiaries	274,778			—			—			(274,778		)	—
Net income (loss)	$	269,163		$	276,222		$	(1,444	)	$	(274,778	)	$	269,163
Comprehensive income (loss)	$	268,277		$	276,726		$	(2,834	)	$	(273,892	)	$	268,277
Condensed Consolidating Financial Information Statement Of Cash Flows	'
	Condensed Consolidating Financial Information for the Six Months Ended June 30, 2014
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Cash Flows
	Cash flows from operating activities
	Net income (loss)	$	327,475		$	334,394		$	(2,102	)	$	(332,292	)	$	327,475
	Adjustments to reconcile net income
	(loss) to net cash (used for) provided
	by operating activities
	Depreciation and amortization	730			93,403			1,071			—			95,204
	Deferred income taxes	(292		)	19,744			(93		)	—			19,359
	Net changes in working capital	(336,669		)	(3,271		)	(2,148		)	332,292			(9,796		)
	and other
	Net cash (used for) provided by	(8,756		)	444,270			(3,272		)	—			432,242
	operating activities
	Cash flows from investing activities
	Additions to property, plant and	—			(216,529		)	(383		)	—			(216,912		)
	equipment
	Proceeds from disposition of assets	—			12			1			—			13
	Proceeds from sales and maturities of	342,045			—			—			—			342,045
	securities
	Purchase of securities	(117,332		)	—			—			—			(117,332		)
	Settlements of derivative instruments	—			(290		)	—			—			(290		)
	Net cash provided by (used for)	224,713			(216,807		)	(382		)	—			7,524
	investing activities
	Cash flows from financing activities
	Intercompany financing	221,745			(224,871		)	3,126			—			—
	Dividends paid	(33,623		)	—			—			—			(33,623		)
	Proceeds from exercise of stock options	4,187			—			—			—			4,187
	Windfall tax benefits from share-based	4,436			—			—			—			4,436
	payment arrangements
	Net cash provided by (used for)	196,745			(224,871		)	3,126			—			(25,000		)
	financing activities
	Net increase (decrease) in cash and	412,702			2,592			(528		)	—			414,766
	cash equivalents
	Cash and cash equivalents at beginning	420,948			6,227			34,126			—			461,301
	of period
	Cash and cash equivalents at end of period	$	833,650		$	8,819		$	33,598		$	—		$	876,067
	Condensed Consolidating Financial Information for the Six Months Ended June 30, 2013
		Westlake			Guarantor			Non-			Eliminations			Consolidated
		Chemical			Subsidiaries			Guarantor
		Corporation						Subsidiaries
	Statement of Cash Flows
	Cash flows from operating activities
	Net income (loss)	$	269,163		$	276,222		$	(1,444	)	$	(274,778	)	$	269,163
	Adjustments to reconcile net income
	(loss) to net cash (used for) provided
	by operating activities
	Depreciation and amortization	730			74,298			1,267			—			76,295
	Deferred income taxes	(1,230		)	61,610			45			—			60,425
	Net changes in working capital	(279,039		)	(153,604		)	7,462			274,778			(150,403		)
	and other
	Net cash (used for) provided by	(10,376		)	258,526			7,330			—			255,480
	operating activities
	Cash flows from investing activities
	Acquisition of business	—			(178,309		)	—			—			(178,309		)
	Additions to equity investments	—			(6,113		)	—			—			(6,113		)
	Additions to property, plant and	—			(295,859		)	(2,014		)	—			(297,873		)
	equipment
	Construction of assets pending	—			(136		)	—			—			(136		)
	sale-leaseback
	Proceeds from disposition of assets	—			2			60			—			62
Proceeds from repayment of loan	—			—			167			—			167
to affiliate
Proceeds from sales and maturities of	209,785			—			—			—			209,785
securities
Purchase of securities	(114,881		)	—			—			—			(114,881		)
Settlements of derivative instruments	—			(1,588		)	—			—			(1,588		)
Net cash provided by (used for)	94,904			(482,003		)	(1,787		)	—			(388,886		)
investing activities
Cash flows from financing activities
Intercompany financing	(214,927		)	219,968			(5,041		)	—			—
Dividends paid	(25,120		)	—			—			—			(25,120		)
Proceeds from exercise of stock options	2,656			—			—			—			2,656
Repurchase of common stock for treasury	(13,283		)	—			—			—			(13,283		)
Windfall tax benefits from share-based	4,576			—			—			—			4,576
payment arrangements
Net cash (used for) provided by	(246,098		)	219,968			(5,041		)	—			(31,171		)
financing activities
Net (decrease) increase in cash and	(161,570		)	(3,509		)	502			—			(164,577		)
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	$	592,311		$	3,464		$	29,726		$	—		$	625,501

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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Held-to-maturity Securities	'	'
Cash Equivalents [Line Items]	'	'
Cash Equivalents, at Carrying Value	$747,008	$263,967

Financial_Instruments_Marketab

Financial Instruments Marketable Securities (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'	'
Current	$0	$239,388
Noncurrent	18,879	0
Total Available-for-sale Securities	$18,879	$239,388

Financial_Instruments_Availabl

Financial Instruments Available-for-sale Securities (Details) (USD $)	3 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Cost	$14,985	$14,985	$239,113
GrossUnrealizedGain	3,894	3,894	434
GrossUnrealizedLoss	0	0	-159
Fair Value	-18,879	-18,879	-239,388
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	2,495	2,495	176
Available-for-sale Securities, Income Tax Expense on Change in Unrealized Holding Gain (Loss)	1,399	1,399	99
Proceeds from Sale of Available-for-sale Securities	311,926	342,045	'
Gross Realized Gains	1,298	1,311	'
Gross Realized Losses	-61	-99	'
Corporate bonds	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Cost	'	'	108,300
GrossUnrealizedGain	'	'	340
GrossUnrealizedLoss	'	'	-69
Fair Value	'	'	-108,571
U.S. government debt	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Cost	'	'	106,335
GrossUnrealizedGain	'	'	60
GrossUnrealizedLoss	'	'	-79
Fair Value	'	'	-106,316
Asset-backed securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Cost	'	'	24,478
GrossUnrealizedGain	'	'	34
GrossUnrealizedLoss	'	'	-11
Fair Value	'	'	-24,501
Equity Securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Cost	14,985	14,985	'
GrossUnrealizedGain	3,894	3,894	'
GrossUnrealizedLoss	0	0	'
Fair Value	($18,879)	($18,879)	'

Accounts_Receivable_Details

Accounts Receivable (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts Receivable, Net [Abstract]	'	'
Trade customers	$445,156	$410,302
Affiliates	300	315
Allowance for doubtful accounts	-12,052	-11,741
Receivables from trade customers and affiliates, net	433,404	398,876
Federal and state taxes	7,512	20,820
Other	13,365	8,761
Accounts receivable, net	$454,281	$428,457

Inventories_Details

Inventories (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Finished products	$218,817	$232,658
Feedstock, additives and chemicals	159,099	180,646
Materials and supplies	59,603	58,575
Inventories	$437,519	$471,879

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'	'	'	'	'
Property, plant and equipment	$2,217,049	'	$2,217,049	'	$2,088,014
Depreciation expense on property, plant and equipment	$39,859	$32,615	$77,920	$63,535	'

Other_Assets_Additional_Inform

Other Assets (Additional Information) (Detail) (USD $)	3 Months Ended		6 Months Ended				1 Months Ended			1 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Apr. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Apr. 30, 2014	Apr. 30, 2014
					Olefins	Olefins	Vinyls	Vinyls	Vinyls	Maximum	Minimum
Other Assets [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Amortization expense on intangible assets, included in other assets	$9,008	$7,959	$17,284	$12,760	'	'	'	'	'	'	'
Goodwill	'	'	'	'	$29,990	$29,990	'	$32,026	$32,026	'	'
Number of years forecasted	'	'	'	'	'	'	'10 years	'	'	'	'
Discounted Cash Flow Projections Period	'	'	'	'	'	'	'	'	'	'2023	'2014
Discounted Cash Flow Methodology, Goodwill Impairment, Discount Rate	'	'	'	'	'	'	8.80%	'	'	'	'
Discounted Cash Flow Methodology, Goodwill Impairment, Cash Flow Percentage Decrease Without Impairment	'	'	'	'	'	'	10.00%	'	'	'	'

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Long-term debt	$763,938	$763,879
3.60% Senior Notes Due 2022	'	'
Debt Instrument [Line Items]	'	'
Maturity	'2022	'
Stated interest rate	3.60%	'
Senior notes	249,049	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	Jun. 30, 2014
Line of Credit Facility [Line Items]	'
Maximum borrowing capacity	$400,000
Percentage of commitment on borrowing availability	0.38%
Letters of credit outstanding	17,773
Remaining borrowing capacity	382,227
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
LIBOR [Member] | Minimum	'
Line of Credit Facility [Line Items]	'
Percentage added to basis to find interest rate	1.75%
LIBOR [Member] | Maximum	'
Line of Credit Facility [Line Items]	'
Percentage added to basis to find interest rate	2.25%
Base Rate [Member] | Minimum	'
Line of Credit Facility [Line Items]	'
Percentage added to basis to find interest rate	0.25%
Base Rate [Member] | 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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'	'	'	'
Stock-based compensation expense	$2,289	$1,626	$4,511	$3,124

Derivative_Instruments_Textual

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

Derivative_Instruments_Fair_Va

Derivative Instruments (Fair Values of Derivative Instruments in Consolidated Balance Sheets) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative liabilities	$924	$176
Accounts Receivable	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative assets	937	296
Forward Contracts [Member] | Accrued Liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Not designated as hedging instruments, Derivative Liabilities	924	176
Forward Contracts [Member] | Accounts Receivable	'	'
Derivatives, Fair Value [Line Items]	'	'
Not designated as hedging instruments, Derivative Assets	$937	$296

Derivative_Instruments_Impact_

Derivative Instruments (Impact of Derivative Instruments on Income) (Details) (Cost of Sales, USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 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	($1,615)	$0	($220)
Designated As Fair Value Hedges | Forward Contracts [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (Loss) Recognized in Income on Derivative	0	1,533	0	-110
Derivatives Not Designated As Hedging Instruments | Forward Contracts [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (Loss) Recognized in Income on Derivative	$240	$9,382	($371)	$16,717

Fair_Value_Measurements_Summar

Fair Value Measurements (Summary of Assets and Liabilities Accounted at Fair Value on Recurring Basis) (Details) (USD $)	Jun. 30, 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	$0	$239,388
Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for Sale	18,879	239,388
Recurring | Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for Sale	18,879	91,595
Recurring | Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for Sale	0	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	937	296
Risk management liabilities - Commodity forward contracts	-924	-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	430	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	507	248
Risk management liabilities - Commodity forward contracts	($924)	($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

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 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

'

$249,049

$248,990

$250,510

$236,905

'

$100,000

$100,000

$115,750

$109,490

'

$250,000

$250,000

$278,525

$265,148

'

$89,000

$89,000

$104,670

$94,606

'

$65,000

$65,000

$76,445

$69,094

'

'

'

'

'

Loans

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$10,889

$10,889

$10,889

$10,889

Income_Taxes_Detail

Income Taxes (Detail) (USD $)	3 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'
Effective income tax rate	36.10%	34.90%	'
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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	134,938	142,912	102,480	108,000

Earnings_per_Share_Schedule_of

Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]	'	'	'	'
Net income	$169,443	$145,816	$327,475	$269,163
Less: Net income attributable to participating securities	-360	-512	-746	-1,091
Net income attributable to common shareholders	$169,083	$145,304	$326,729	$268,072

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				6 Months Ended
	Feb. 14, 2014	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Earnings Per Share [Abstract]	'	'		'		'		'
Basic	'	133,223,705	[1]	133,259,218	[1]	133,148,398	[1]	133,255,322	[1]
Plus incremental shares from: Assumed exercise of options	'	544,185	[1]	531,972	[1]	542,438	[1]	549,224	[1]
Weighted average common shares-diluted	'	133,767,890	[1]	133,791,190	[1]	133,690,836	[1]	133,804,546	[1]
Earnings per share: Basic	'	$1.27	[1]	$1.09	[1]	$2.45	[1]	$2.01	[1]
Earnings per share: Diluted	'	$1.26	[1]	$1.09	[1]	$2.44	[1]	$2.01	[1]
Stock split conversion ratio	2	'		'		'		'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	'	134,938		142,912		102,480		108,000
[1]	Share amounts and per share data for the three and six months ended June 30, 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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	$84	$275	$167	$539
Interest cost	576	515	1,170	1,016
Expected return on plan assets	-777	-713	-1,586	-1,427
Amortization of prior service cost	74	74	148	148
Amortization of net loss	70	510	134	940
Net periodic benefit cost	27	661	33	1,216
Post-Retirement Healthcare	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	5	2	11	5
Interest cost	181	147	362	294
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	13	21	25	42
Amortization of net loss	69	90	138	179
Net periodic benefit cost	$268	$260	$536	$520

Pension_and_PostRetirement_Ben3

Pension and Post-Retirement Benefit Costs (Additional Information) (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Defined Benefit Plan Disclosure [Line Items]	'	'
Document Fiscal Year Focus	'2014	'
Salaried Pension Plan	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Employer contribution	$965	$388
Expected additional contributions	1,812	'
Wage Pension Plan	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Employer contribution	580	350
Expected additional contributions	$626	'

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income Changes in AOCI (Details) (USD $)	3 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2014	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Accumulated other comprehensive income (loss), beginning balance	'	($2,616)	($10,840)
Other comprehensive loss before reclassifications	-1,691	2,986	'
Amounts reclassified from accumulated other comprehensive loss	805	-502	'
Net other comprehensive income (loss) for the period	-886	2,484	'
Accumulated other comprehensive income (loss), ending balance	-11,726	-132	-10,840
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	-301	-20	'
Amounts reclassified from accumulated other comprehensive loss	805	275	'
Net other comprehensive income (loss) for the period	504	255	'
Accumulated other comprehensive income (loss), ending balance	-15,847	-6,441	-16,351
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	-1,390	-90	'
Amounts reclassified from accumulated other comprehensive loss	0	0	'
Net other comprehensive income (loss) for the period	-1,390	-90	'
Accumulated other comprehensive income (loss), ending balance	4,121	3,814	5,511
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	'	3,096	'
Amounts reclassified from accumulated other comprehensive loss	'	-777	'
Net other comprehensive income (loss) for the period	'	2,319	'
Accumulated other comprehensive income (loss), ending balance	'	$2,495	'

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income Reclassifications in AOCI (Details) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Income before income taxes	$261,850		$229,789		$503,257		$421,082
Realized gain on available-for-sale investments	4,601		-95		7,110		3,424
Provision for income taxes	-92,407		-83,973		-175,782		-151,919
Net income	169,443		145,816		327,475		269,163
Reclassification out of Accumulated Other Comprehensive Income	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Net income	653		-427		502		-805
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]	-173	[1]	-190	[2]
Net loss	-139	[1]	-600	[1]	-272	[1]	-1,119	[2]
Income before income taxes	-226		-695		-445		-1,309
Provision for income taxes	86		268		170		504
Net income	-140		-427		-275		-805
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Realized gain on available-for-sale investments	1,237		0		1,212		0
Provision for income taxes	-444		0		-435		0
Net income	$793		$0		$777		$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.
[2]	Share amounts and per share data for the three and six months ended June 30, 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.

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

Share_Capital_Details

Share Capital (Details) (USD $)	1 Months Ended
In Thousands, except Share data, unless otherwise specified	Aug. 31, 2011	Jun. 30, 2014	16-May-14	15-May-14	Dec. 31, 2013
Equity [Abstract]	'	'	'	'	'
Common stock, shares authorized	'	300,000,000	300,000,000	150,000,000	150,000,000
Common stock, par value	'	$0.01	$0.01	'	$0.01
Common stock, shares issued	'	134,681,372	'	'	134,580,208
Common stock, held in treasury	'	1,197,617	'	'	1,252,922
Stock repurchase program, authorized amount	$100,000	'	'	'	'
Shares repurchased	'	1,252,922	'	'	1,252,922

Segment_Information_Additional

Segment Information (Additional Information) (Detail)	3 Months Ended
	Jun. 30, 2014
	Segment
Segment Reporting [Abstract]	'
Number of segments	2

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	$998,576	$939,047	$2,026,252	$1,803,694
Income (loss) from operations	266,788	235,227	514,843	429,282
Depreciation and amortization	48,502	40,210	94,474	75,566
Other (expense) income, net	4,601	-95	7,110	3,424
Provision for (benefit from) income taxes	92,407	83,973	175,782	151,919
Capital expenditures	106,171	147,089	216,912	297,873
Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	699,053	623,341	1,421,851	1,206,186
Income (loss) from operations	238,657	187,661	510,990	348,719
Depreciation and amortization	26,721	26,554	53,368	49,900
Other (expense) income, net	1,199	1,151	2,653	5,162
Provision for (benefit from) income taxes	83,502	70,140	177,052	125,617
Capital expenditures	43,448	28,040	72,522	78,080
Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	299,523	315,706	604,401	597,508
Income (loss) from operations	38,129	52,906	17,015	96,569
Depreciation and amortization	21,623	13,534	40,791	25,418
Other (expense) income, net	-213	-520	-247	-946
Provision for (benefit from) income taxes	10,430	19,690	360	33,410
Capital expenditures	62,262	118,983	143,382	219,300
Corporate and Other	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Income (loss) from operations	-9,998	-5,340	-13,162	-16,006
Depreciation and amortization	158	122	315	248
Other (expense) income, net	3,615	-726	4,704	-792
Provision for (benefit from) income taxes	-1,525	-5,857	-1,630	-7,108
Capital expenditures	461	66	1,008	493
Polyethylene | Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	475,503	413,693	962,647	834,461
Ethylene, Styrene And Other | Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	223,550	209,648	459,204	371,725
PVC, Caustic Soda And Other | Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	168,762	205,104	359,289	400,350
Building Products | Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	130,761	110,602	245,112	197,158
Intersegment sales	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	35,113	75,314	92,309	145,861
Intersegment sales | Olefins	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	34,782	74,870	91,635	145,153
Intersegment sales | Vinyls	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net external sales	$331	$444	$674	$708

Segment_Information_Reconcilia

Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting [Abstract]	'	'	'	'
Income from operations	$266,788	$235,227	$514,843	$429,282
Interest expense	-9,539	-5,343	-18,696	-11,624
Other (expense) income, net	4,601	-95	7,110	3,424
Income before income taxes	$261,850	$229,789	$503,257	$421,082

Segment_Information_Total_Asse

Segment Information (Total Assets) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	$4,369,369	$4,060,909
Olefins	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	1,607,210	1,557,510
Vinyls	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	1,808,849	1,740,595
Corporate and Other	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total assets	$953,310	$762,804

Subsequent_Events_Initial_Publ

Subsequent Events (Initial Public Offering) (Details) (Subsequent Event [Member], USD $)	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Aug. 04, 2014
Subsidiaries [Member] | Westlake Chemical Partners LP [Member] | IPO [Member]	'
Subsequent Event [Line Items]	'
Percentage sold to public in IPO	47.80%
Subsidiaries [Member] | Cash Reserve Turnaround [Member] | Westlake Chemical OpCo LP [Member] | IPO [Member]	'
Subsequent Event [Line Items]	'
Amount used from proceeds	55,400
Subsidiaries [Member] | Preformation Capital Expenditure [Member] | Westlake Chemical OpCo LP [Member] | IPO [Member]	'
Subsequent Event [Line Items]	'
Amount used from proceeds	155,700
Subsidiaries [Member] | Intercompany Debt [Member] | Westlake Chemical OpCo LP [Member] | IPO [Member]	'
Subsequent Event [Line Items]	'
Amount used from proceeds	75,144
Limited Partner [Member] | IPO [Member]	'
Subsequent Event [Line Items]	'
Limited partner interest	89.40%
Limited Partner [Member] | Subsidiaries [Member] | Westlake Chemical Partners LP [Member] | IPO [Member]	'
Subsequent Event [Line Items]	'
Number of units sold in public offering	12,937,500
Approximate proceeds from sale of units	286,263
Estimated offering expenses from sale of partnership units	24,237
Limited partner interest	10.60%
Limited Partner [Member] | Subsidiaries [Member] | Westlake Chemical Partners LP [Member] | Over-Allotment Option [Member]	'
Subsequent Event [Line Items]	'
Number of units sold in public offering	1,687,500

Subsequent_Events_Acquisition_

Subsequent Events (Acquisition) (Details) (Subsequent Event [Member], EUR €)	0 Months Ended
In Thousands, unless otherwise specified	Jul. 31, 2014
Subsequent Event [Line Items]	'
Amount paid in acquisition	€ 490,000
PVC Resin Member [Member]	'
Subsequent Event [Line Items]	'
Annual capacity by acquiree	1,700,000,000
Vinyl Chloride Monomer [Member]	'
Subsequent Event [Line Items]	'
Annual capacity by acquiree	1,500,000,000
Caustic Soda [Member]	'
Subsequent Event [Line Items]	'
Annual capacity by acquiree	1,000,000,000

Guarantor_Disclosures_Addition

Guarantor Disclosures (Additional Information) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 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 $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	$876,067	$461,301	$625,501	$790,078
Marketable Securities, Current	0	239,388	'	'
Accounts receivable, net	454,281	428,457	'	'
Inventories	437,519	471,879	'	'
Prepaid expenses and other current assets	20,468	13,888	'	'
Deferred income taxes	34,168	34,169	'	'
Total current assets	1,822,503	1,649,082	'	'
Property, plant and equipment, net	2,217,049	2,088,014	'	'
Equity investments	68,867	66,875	'	'
Other assets, net	260,950	256,938	'	'
Total assets	4,369,369	4,060,909	'	'
Accounts payable	219,600	249,613	'	'
Accrued liabilities	167,329	155,245	'	'
Total current liabilities	386,929	404,858	'	'
Long-term debt	763,938	763,879	'	'
Deferred income taxes	458,790	437,976	'	'
Other liabilities	31,639	35,593	'	'
Stockholders' equity	2,728,073	2,418,603	'	'
Total liabilities and stockholders' equity	4,369,369	4,060,909	'	'
Westlake Chemical Corporation	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	833,650	420,948	592,311	753,881
Marketable Securities, Current	0	239,388	'	'
Accounts receivable, net	12,499	3,879	'	'
Inventories	0	0	'	'
Prepaid expenses and other current assets	95	778	'	'
Deferred income taxes	441	441	'	'
Total current assets	846,685	665,434	'	'
Property, plant and equipment, net	0	0	'	'
Equity investments	3,148,210	2,815,752	'	'
Other assets, net	32,535	15,393	'	'
Total assets	4,027,430	3,496,579	'	'
Accounts payable	533,491	316,652	'	'
Accrued liabilities	12,817	8,334	'	'
Total current liabilities	546,308	324,986	'	'
Long-term debt	753,049	752,990	'	'
Deferred income taxes	0	0	'	'
Other liabilities	0	0	'	'
Stockholders' equity	2,728,073	2,418,603	'	'
Total liabilities and stockholders' equity	4,027,430	3,496,579	'	'
Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	8,819	6,227	3,464	6,973
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	995,379	738,156	'	'
Inventories	419,659	456,306	'	'
Prepaid expenses and other current assets	18,169	11,312	'	'
Deferred income taxes	33,422	33,422	'	'
Total current assets	1,475,448	1,245,423	'	'
Property, plant and equipment, net	2,210,754	2,081,091	'	'
Equity investments	103,650	100,326	'	'
Other assets, net	231,938	246,125	'	'
Total assets	4,021,790	3,672,965	'	'
Accounts payable	204,830	223,134	'	'
Accrued liabilities	177,648	161,140	'	'
Total current liabilities	382,478	384,274	'	'
Long-term debt	10,889	10,889	'	'
Deferred income taxes	462,930	443,026	'	'
Other liabilities	31,599	35,533	'	'
Stockholders' equity	3,133,894	2,799,243	'	'
Total liabilities and stockholders' equity	4,021,790	3,672,965	'	'
Non-Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Cash and cash equivalents	33,598	34,126	29,726	29,224
Marketable Securities, Current	0	0	'	'
Accounts receivable, net	4,145	2,755	'	'
Inventories	17,860	15,573	'	'
Prepaid expenses and other current assets	2,204	1,798	'	'
Deferred income taxes	305	306	'	'
Total current assets	58,112	54,558	'	'
Property, plant and equipment, net	6,295	6,923	'	'
Equity investments	30,186	31,518	'	'
Other assets, net	1,249	1,199	'	'
Total assets	95,842	94,198	'	'
Accounts payable	14,870	10,649	'	'
Accrued liabilities	1,015	1,282	'	'
Total current liabilities	15,885	11,931	'	'
Long-term debt	0	0	'	'
Deferred income taxes	632	729	'	'
Other liabilities	40	60	'	'
Stockholders' equity	79,285	81,478	'	'
Total liabilities and stockholders' equity	95,842	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	-557,742	-316,333	'	'
Inventories	0	0	'	'
Prepaid expenses and other current assets	0	0	'	'
Deferred income taxes	0	0	'	'
Total current assets	-557,742	-316,333	'	'
Property, plant and equipment, net	0	0	'	'
Equity investments	-3,213,179	-2,880,721	'	'
Other assets, net	-4,772	-5,779	'	'
Total assets	-3,775,693	-3,202,833	'	'
Accounts payable	-533,591	-300,822	'	'
Accrued liabilities	-24,151	-15,511	'	'
Total current liabilities	-557,742	-316,333	'	'
Long-term debt	0	0	'	'
Deferred income taxes	-4,772	-5,779	'	'
Other liabilities	0	0	'	'
Stockholders' equity	-3,213,179	-2,880,721	'	'
Total liabilities and stockholders' equity	($3,775,693)	($3,202,833)	'	'

Guarantor_Disclosures_Condense1

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	$998,576	$939,047	$2,026,252	$1,803,694
Cost of sales	692,605	665,560	1,433,271	1,302,398
Gross profit	305,971	273,487	592,981	501,296
Selling, general and administrative expenses	39,183	38,260	78,138	72,014
Income from operations	266,788	235,227	514,843	429,282
Interest expense	-9,539	-5,343	-18,696	-11,624
Other (expense) income, net	4,601	-95	7,110	3,424
Income before income taxes	261,850	229,789	503,257	421,082
Provision for (benefit from) income taxes	92,407	83,973	175,782	151,919
Equity in net income of subsidiaries	0	0	0	0
Net income	169,443	145,816	327,475	269,163
Comprehensive income (loss)	171,093	145,122	329,959	268,277
Westlake Chemical Corporation	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	529	552	1,075	1,062
Income from operations	-529	-552	-1,075	-1,062
Interest expense	-9,535	-5,332	-18,690	-11,590
Other (expense) income, net	7,137	-404	12,351	3,905
Income before income taxes	-2,927	-6,288	-7,414	-8,747
Provision for (benefit from) income taxes	-1,039	-2,258	-2,597	-3,132
Equity in net income of subsidiaries	171,331	149,846	332,292	274,778
Net income	169,443	145,816	327,475	269,163
Comprehensive income (loss)	171,093	145,122	329,959	268,277
Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	988,944	928,782	2,009,373	1,784,867
Cost of sales	683,790	657,457	1,418,140	1,286,743
Gross profit	305,154	271,325	591,233	498,124
Selling, general and administrative expenses	37,231	36,055	74,294	67,764
Income from operations	267,923	235,270	516,939	430,360
Interest expense	-4	-11	-6	-34
Other (expense) income, net	-1,743	1,638	-3,834	1,348
Income before income taxes	266,176	236,897	513,099	431,674
Provision for (benefit from) income taxes	93,595	86,401	178,705	155,452
Equity in net income of subsidiaries	0	0	0	0
Net income	172,581	150,496	334,394	276,222
Comprehensive income (loss)	172,701	150,622	334,649	276,726
Non-Guarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	11,753	13,684	20,870	24,224
Cost of sales	10,936	11,522	19,122	21,052
Gross profit	817	2,162	1,748	3,172
Selling, general and administrative expenses	1,423	1,653	2,769	3,188
Income from operations	-606	509	-1,021	-16
Interest expense	0	0	0	0
Other (expense) income, net	-793	-1,329	-1,407	-1,829
Income before income taxes	-1,399	-820	-2,428	-1,845
Provision for (benefit from) income taxes	-149	-170	-326	-401
Equity in net income of subsidiaries	0	0	0	0
Net income	-1,250	-650	-2,102	-1,444
Comprehensive income (loss)	-442	-1,470	-2,192	-2,834
Eliminations	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net sales	-2,121	-3,419	-3,991	-5,397
Cost of sales	-2,121	-3,419	-3,991	-5,397
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Income from operations	0	0	0	0
Interest expense	0	0	0	0
Other (expense) income, net	0	0	0	0
Income before income taxes	0	0	0	0
Provision for (benefit from) income taxes	0	0	0	0
Equity in net income of subsidiaries	-171,331	-149,846	-332,292	-274,778
Net income	-171,331	-149,846	-332,292	-274,778
Comprehensive income (loss)	($172,259)	($149,152)	($332,457)	($273,892)

Guarantor_Disclosures_Condense2

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	$327,475	$269,163
Depreciation and amortization	95,204	76,295
Deferred income taxes	19,359	60,425
Net changes in working capital and other	-9,796	-150,403
Net cash provided by operating activities	432,242	255,480
Payments to Acquire Businesses, Net of Cash Acquired	0	-178,309
Payments to Acquire Equity Method Investments	0	-6,113
Additions to property, plant and equipment	-216,912	-297,873
Payments for Construction of Assets Pending Sale Leaseback	0	136
Proceeds from disposition of assets	13	62
Proceeds from repayment of loan to affiliate	0	167
Proceeds from sales of equity securities	342,045	209,785
Purchase of securities and other investments	-117,332	-114,881
Settlements of derivative instruments	-290	-1,588
Net cash used for investing activities	7,524	-388,886
Intercompany financing	0	0
Dividends paid	-33,623	-25,120
Proceeds from exercise of stock options	4,187	2,656
Repurchase of common stock for treasury	0	13,283
Windfall tax benefits from share-based payment arrangements	4,436	4,576
Net cash provided by financing activities	-25,000	-31,171
Net increase in cash and cash equivalents	414,766	-164,577
Cash and cash equivalents at beginning of period	461,301	790,078
Cash and cash equivalents at end of period	876,067	625,501
Westlake Chemical Corporation	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	327,475	269,163
Depreciation and amortization	730	730
Deferred income taxes	-292	-1,230
Net changes in working capital and other	-336,669	-279,039
Net cash provided by operating activities	-8,756	-10,376
Payments to Acquire Businesses, Net of Cash Acquired	'	0
Payments to Acquire Equity Method Investments	'	0
Additions to property, plant and equipment	0	0
Payments for Construction of Assets Pending Sale Leaseback	'	0
Proceeds from disposition of assets	0	0
Proceeds from repayment of loan to affiliate	'	0
Proceeds from sales of equity securities	342,045	209,785
Purchase of securities and other investments	-117,332	-114,881
Settlements of derivative instruments	0	0
Net cash used for investing activities	224,713	94,904
Intercompany financing	221,745	-214,927
Dividends paid	-33,623	-25,120
Proceeds from exercise of stock options	4,187	2,656
Repurchase of common stock for treasury	'	13,283
Windfall tax benefits from share-based payment arrangements	4,436	4,576
Net cash provided by financing activities	196,745	-246,098
Net increase in cash and cash equivalents	412,702	-161,570
Cash and cash equivalents at beginning of period	420,948	753,881
Cash and cash equivalents at end of period	833,650	592,311
Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	334,394	276,222
Depreciation and amortization	93,403	74,298
Deferred income taxes	19,744	61,610
Net changes in working capital and other	-3,271	-153,604
Net cash provided by operating activities	444,270	258,526
Payments to Acquire Businesses, Net of Cash Acquired	'	-178,309
Payments to Acquire Equity Method Investments	'	-6,113
Additions to property, plant and equipment	-216,529	-295,859
Payments for Construction of Assets Pending Sale Leaseback	'	136
Proceeds from disposition of assets	12	2
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	-290	-1,588
Net cash used for investing activities	-216,807	-482,003
Intercompany financing	-224,871	219,968
Dividends paid	0	0
Proceeds from exercise of stock options	0	0
Repurchase of common stock for treasury	'	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	-224,871	219,968
Net increase in cash and cash equivalents	2,592	-3,509
Cash and cash equivalents at beginning of period	6,227	6,973
Cash and cash equivalents at end of period	8,819	3,464
Non-Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	-2,102	-1,444
Depreciation and amortization	1,071	1,267
Deferred income taxes	-93	45
Net changes in working capital and other	-2,148	7,462
Net cash provided by operating activities	-3,272	7,330
Payments to Acquire Businesses, Net of Cash Acquired	'	0
Payments to Acquire Equity Method Investments	'	0
Additions to property, plant and equipment	-383	-2,014
Payments for Construction of Assets Pending Sale Leaseback	'	0
Proceeds from disposition of assets	1	60
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	-382	-1,787
Intercompany financing	3,126	-5,041
Dividends paid	0	0
Proceeds from exercise of stock options	0	0
Repurchase of common stock for treasury	'	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	3,126	-5,041
Net increase in cash and cash equivalents	-528	502
Cash and cash equivalents at beginning of period	34,126	29,224
Cash and cash equivalents at end of period	33,598	29,726
Eliminations	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net income	-332,292	-274,778
Depreciation and amortization	0	0
Deferred income taxes	0	0
Net changes in working capital and other	332,292	274,778
Net cash provided by operating activities	0	0
Payments to Acquire Businesses, Net of Cash Acquired	'	0
Payments to Acquire Equity Method Investments	'	0
Additions to property, plant and equipment	0	0
Payments for Construction of Assets Pending Sale Leaseback	'	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
Repurchase of common stock for treasury	'	0
Windfall tax benefits from share-based payment arrangements	0	0
Net cash provided by financing activities	0	0
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