Condensed Consolidating Financial Information Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 913,958	$ 925,049	$ 1,948,825	$ 1,792,301
Cost of sales	712,062	757,954	1,574,292	1,457,622
Gross profit	201,896	167,095	374,533	334,679
Selling, general and administrative expenses	30,918	28,726	57,930	55,673
(Loss) income from operations	170,978	138,369	316,603	279,006
Interest expense	(11,571)	(12,802)	(23,748)	(25,722)
Gain from sales of equity securities	15,952		15,952
Other income (expense), net	1,107	1,632	2,454	2,839
Income before income taxes	176,466	127,199	311,261	256,123
(Benefit from) provision for income taxes	60,965	46,150	107,947	91,530
Net income (loss)	115,501	81,049	203,314	164,593
Comprehensive income (loss)	97,500	81,126	202,519	165,478
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative expenses	497	1,012	1,002	2,024
(Loss) income from operations	(497)	(1,012)	(1,002)	(2,024)
Interest expense	(11,562)	(12,767)	(23,733)	(25,676)
Gain from sales of equity securities	1		1
Other income (expense), net	3,954	1,819	7,488	5,015
Income before income taxes	(8,104)	(11,960)	(17,246)	(22,685)
(Benefit from) provision for income taxes	(3,434)	(3,831)	(6,607)	(7,349)
Equity in net income of subsidiaries	120,171	89,178	213,953	179,929
Net income (loss)	115,501	81,049	203,314	164,593
Comprehensive income (loss)	97,500	81,126	202,519	165,478
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	902,684	914,907	1,929,016	1,774,860
Cost of sales	703,421	748,539	1,558,408	1,440,781
Gross profit	199,263	166,368	370,608	334,079
Selling, general and administrative expenses	28,933	26,292	53,688	51,041
(Loss) income from operations	170,330	140,076	316,920	283,038
Interest expense	(9)	(35)	(15)	(46)
Gain from sales of equity securities	15,951		15,951
Other income (expense), net	(1,279)	(326)	(2,978)	(3,041)
Income before income taxes	184,993	139,715	329,878	279,951
(Benefit from) provision for income taxes	65,400	49,911	115,633	99,057
Net income (loss)	119,593	89,804	214,245	180,894
Comprehensive income (loss)	102,562	90,090	213,908	181,455
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	13,435	11,477	23,278	19,622
Cost of sales	10,802	10,750	19,353	19,022
Gross profit	2,633	727	3,925	600
Selling, general and administrative expenses	1,488	1,422	3,240	2,608
(Loss) income from operations	1,145	(695)	685	(2,008)
Other income (expense), net	(1,568)	139	(2,056)	865
Income before income taxes	(423)	(556)	(1,371)	(1,143)
(Benefit from) provision for income taxes	(1,001)	70	(1,079)	(178)
Net income (loss)	578	(626)	(292)	(965)
Comprehensive income (loss)	129	(835)	(229)	(641)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(2,161)	(1,335)	(3,469)	(2,181)
Cost of sales	(2,161)	(1,335)	(3,469)	(2,181)
Equity in net income of subsidiaries	(120,171)	(89,178)	(213,953)	(179,929)
Net income (loss)	(120,171)	(89,178)	(213,953)	(179,929)
Comprehensive income (loss)	$ (102,691)	$ (89,255)	$ (213,679)	$ (180,814)