Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Net sales	$ 1,188,037	$ 1,253,227	$ 3,476,570	$ 3,279,479
Cost of sales	876,761	891,707	2,527,567	2,324,978
Gross profit	311,276	361,520	949,003	954,501
Selling, general and administrative expenses	57,248	54,759	170,321	132,897
Income from operations	254,028	306,761	778,682	821,604
Other income (expense)
Interest expense	(8,211)	(9,486)	(26,760)	(28,182)
Other income, net	2,636	(2,670)	33,790	4,440
Income before income taxes	248,453	294,605	785,712	797,862
Provision for income taxes	60,033	124,449	236,824	300,231
Net income	188,420	170,156	548,888	497,631
Net income attributable to noncontrolling interests	4,816	2,399	13,847	2,399
Net income attributable to Westlake Chemical Corporation	$ 183,604	$ 167,757	$ 535,041	$ 495,232
Earnings per common share attributable to Westlake Chemical Corporation
Basic (usd per share)	$ 1.39	$ 1.26	$ 4.04	$ 3.71
Diluted (usd per share)	$ 1.39	$ 1.25	$ 4.02	$ 3.69
Weighted average shares outstanding:
Basic	131,664,296	133,299,458	132,301,814	133,199,304
Diluted	132,121,235	133,846,059	132,786,534	133,743,145
Dividends per common share	$ 0.1815	$ 0.1650	$ 0.5115	$ 0.4170