Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 821,175	$ 968,372	$ 2,770,000	$ 2,760,673
Cost of sales	648,996	821,305	2,223,288	2,278,927
Gross profit	172,179	147,067	546,712	481,746
Selling, general and administrative expenses	29,662	29,736	87,592	85,409
Income (loss) from operations	142,517	117,331	459,120	396,337
Interest expense	(11,934)	(12,727)	(35,682)	(38,449)
Debt retirement costs	(7,082)	0	(7,082)	0
Gain from sales of equity securities	477	0	16,429	0
Other income (expense), net	1,222	1,457	3,676	4,296
Income before income taxes	125,200	106,061	436,461	362,184
Provision for (benefit from) income taxes	38,236	38,131	146,183	129,661
Net income (loss)	86,964	67,930	290,278	232,523
Comprehensive income (loss)	88,666	60,503	291,185	225,981
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative expenses	498	1,125	1,500	3,149
Income (loss) from operations	(498)	(1,125)	(1,500)	(3,149)
Interest expense	(11,919)	(12,727)	(35,652)	(38,403)
Debt retirement costs	(7,082)		(7,082)
Gain from sales of equity securities			1
Other income (expense), net	4,556	1,396	12,044	6,410
Income before income taxes	(14,943)	(12,456)	(32,189)	(35,142)
Provision for (benefit from) income taxes	(4,498)	(4,510)	(11,105)	(11,858)
Equity in net income of subsidiaries	97,409	75,876	311,362	255,807
Net income (loss)	86,964	67,930	290,278	232,523
Comprehensive income (loss)	88,666	60,503	291,185	225,981
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	809,164	956,390	2,738,180	2,731,248
Cost of sales	638,892	810,516	2,197,300	2,251,296
Gross profit	170,272	145,874	540,880	479,952
Selling, general and administrative expenses	27,601	27,242	81,288	78,283
Income (loss) from operations	142,671	118,632	459,592	401,669
Interest expense	(15)	0	(30)	(46)
Gain from sales of equity securities	477		16,428
Other income (expense), net	(2,744)	950	(5,724)	(2,090)
Income before income taxes	140,389	119,582	470,266	399,533
Provision for (benefit from) income taxes	42,596	43,190	158,228	142,247
Net income (loss)	97,793	76,392	312,038	257,286
Comprehensive income (loss)	98,109	70,019	312,017	251,474
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	13,876	12,708	37,154	32,331
Cost of sales	11,969	11,515	31,322	30,537
Gross profit	1,907	1,193	5,832	1,794
Selling, general and administrative expenses	1,563	1,369	4,804	3,977
Income (loss) from operations	344	(176)	1,028	(2,183)
Other income (expense), net	(590)	(889)	(2,644)	(24)
Income before income taxes	(246)	(1,065)	(1,616)	(2,207)
Provision for (benefit from) income taxes	138	(549)	(940)	(728)
Net income (loss)	(384)	(516)	(676)	(1,479)
Comprehensive income (loss)	481	(1,570)	252	(2,209)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(1,865)	(726)	(5,334)	(2,906)
Cost of sales	(1,865)	(726)	(5,334)	(2,906)
Equity in net income of subsidiaries	(97,409)	(75,876)	(311,362)	(255,807)
Net income (loss)	(97,409)	(75,876)	(311,362)	(255,807)
Comprehensive income (loss)	$ (98,590)	$ (68,449)	$ (312,269)	$ (249,265)