Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,004,165	$ 821,175	$ 2,807,859	$ 2,770,000
Cost of sales	699,694	648,996	2,002,092	2,223,288
Gross profit	304,471	172,179	805,767	546,712
Selling, general and administrative expenses	37,869	29,662	109,883	87,592
Income from operations	266,602	142,517	695,884	459,120
Interest expense	(3,297)	(11,934)	(14,921)	(35,682)
Debt retirement costs	0	(7,082)	0	(7,082)
Gain from sales of equity securities	0	477	0	16,429
Other income (expense), net	(287)	1,222	3,137	3,676
Income before income taxes	263,018	125,200	684,100	436,461
Provision for (benefit from) income taxes	92,728	38,236	244,647	146,183
Equity in net income of subsidiaries	0	0	0	0
Net income	170,290	86,964	439,453	290,278
Comprehensive income (loss)	171,095	88,666	439,372	291,185
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	514	498	1,576	1,500
Income from operations	(514)	(498)	(1,576)	(1,500)
Interest expense	(3,292)	(11,919)	(14,882)	(35,652)
Debt retirement costs		(7,082)		(7,082)
Gain from sales of equity securities		0		1
Other income (expense), net	3,585	4,556	7,490	12,044
Income before income taxes	(221)	(14,943)	(8,968)	(32,189)
Provision for (benefit from) income taxes	(70)	(4,498)	(3,202)	(11,105)
Equity in net income of subsidiaries	170,441	97,409	445,219	311,362
Net income	170,290	86,964	439,453	290,278
Comprehensive income (loss)	171,095	88,666	439,372	291,185
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	992,413	809,164	2,777,280	2,738,180
Cost of sales	689,388	638,892	1,976,131	2,197,300
Gross profit	303,025	170,272	801,149	540,880
Selling, general and administrative expenses	35,714	27,601	103,478	81,288
Income from operations	267,311	142,671	697,671	459,592
Interest expense	(5)	(15)	(39)	(30)
Debt retirement costs		0		0
Gain from sales of equity securities		477		16,428
Other income (expense), net	(3,821)	(2,744)	(2,473)	(5,724)
Income before income taxes	263,485	140,389	695,159	470,266
Provision for (benefit from) income taxes	92,849	42,596	248,301	158,228
Equity in net income of subsidiaries	0	0	0	0
Net income	170,636	97,793	446,858	312,038
Comprehensive income (loss)	170,764	98,109	447,490	312,017
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	13,337	13,876	37,561	37,154
Cost of sales	11,891	11,969	32,943	31,322
Gross profit	1,446	1,907	4,618	5,832
Selling, general and administrative expenses	1,641	1,563	4,829	4,804
Income from operations	(195)	344	(211)	1,028
Interest expense	0	0	0	0
Debt retirement costs		0		0
Gain from sales of equity securities		0		0
Other income (expense), net	(51)	(590)	(1,880)	(2,644)
Income before income taxes	(246)	(246)	(2,091)	(1,616)
Provision for (benefit from) income taxes	(51)	138	(452)	(940)
Equity in net income of subsidiaries	0	0	0	0
Net income	(195)	(384)	(1,639)	(676)
Comprehensive income (loss)	351	481	(2,483)	252
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(1,585)	(1,865)	(6,982)	(5,334)
Cost of sales	(1,585)	(1,865)	(6,982)	(5,334)
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
Debt retirement costs		0		0
Gain from sales of equity securities		0		0
Other income (expense), 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	(170,441)	(97,409)	(445,219)	(311,362)
Net income	(170,441)	(97,409)	(445,219)	(311,362)
Comprehensive income (loss)	$ (171,115)	$ (98,590)	$ (445,007)	$ (312,269)