Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 801,041	$ 821,175	$ 913,958	$ 1,034,867	$ 859,175	$ 968,372	$ 925,049	$ 867,252	$ 3,571,041	[1]	$ 3,619,848	[1]	$ 3,171,787	[1]
Cost of sales									2,834,081		3,060,842		2,689,104
Gross profit	190,248	172,179	201,896	172,637	77,260	147,067	167,095	167,584	736,960		559,006		482,683
Selling, general and administrative expenses									121,609		112,210		104,319
Income from operations	156,231	142,517	170,978	145,625	50,459	117,331	138,369	140,637	615,351		446,796		378,364
Interest expense									(43,049)		(50,992)		(39,875)
Debt retirement costs									(7,082)		0		0
Gain from sales of equity securities									16,429		0		0
Other income, (expense), net									3,520		5,628		4,471
Income before income taxes									585,169		401,432		342,960
(Benefit from) provision for income taxes									199,614		142,466		121,567
Equity in net income of subsidiaries									0		0		0
Net income	95,277	86,964	115,501	87,813	26,443	67,930	81,049	83,544	385,555		258,966		221,393
Comprehensive income									383,785		256,929		225,865
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									0		0		0
Cost of sales									0		0		0
Gross profit									0		0		0
Selling, general and administrative expenses									2,004		3,762		4,257
Income from operations									(2,004)		(3,762)		(4,257)
Interest expense									(42,989)		(50,919)		(39,829)
Debt retirement costs									(7,082)
Gain from sales of equity securities									1
Other income, (expense), net									28,171		10,217		15,045
Income before income taxes									(23,903)		(44,464)		(29,041)
(Benefit from) provision for income taxes									1,825		(11,835)		(2,471)
Equity in net income of subsidiaries									411,283		291,595		247,963
Net income									385,555		258,966		221,393
Comprehensive income									383,785		256,929		225,865
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									3,529,685		3,581,470		3,130,513
Cost of sales									2,799,537		3,024,419		2,653,234
Gross profit									730,148		557,051		477,279
Selling, general and administrative expenses									113,133		102,989		95,441
Income from operations									617,015		454,062		381,838
Interest expense									(60)		(73)		(46)
Debt retirement costs									0
Gain from sales of equity securities									16,428
Other income, (expense), net									(21,384)		(4,212)		(12,715)
Income before income taxes									611,999		449,777		369,077
(Benefit from) provision for income taxes									199,057		155,313		122,541
Equity in net income of subsidiaries									0		0
Net income									412,942		294,464		246,536
Comprehensive income									410,549		292,834		250,064
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									48,205		42,202		44,006
Cost of sales									41,393		40,247		38,602
Gross profit									6,812		1,955		5,404
Selling, general and administrative expenses									6,472		5,459		4,621
Income from operations									340		(3,504)		783
Interest expense									0		0		0
Debt retirement costs									0
Gain from sales of equity securities									0
Other income, (expense), net									(3,267)		(377)		2,141
Income before income taxes									(2,927)		(3,881)		2,924
(Benefit from) provision for income taxes									(1,268)		(1,012)		1,497
Equity in net income of subsidiaries									0		0
Net income									(1,659)		(2,869)		1,427
Comprehensive income									(1,036)		(3,276)		2,371
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									(6,849)		(3,824)		(2,732)
Cost of sales									(6,849)		(3,824)		(2,732)
Gross profit									0		0		0
Selling, general and administrative expenses									0		0		0
Income from operations									0		0		0
Interest expense									0		0		0
Debt retirement costs									0
Gain from sales of equity securities									0
Other income, (expense), net									0		0		0
Income before income taxes									0		0		0
(Benefit from) provision for income taxes									0		0		0
Equity in net income of subsidiaries									(411,283)		(291,595)		(247,963)
Net income									(411,283)		(291,595)		(247,963)
Comprehensive income									$ (409,513)		$ (289,558)		$ (252,435)

[1] Revenues are attributed to countries based on location of customer.