Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net sales	$ 1,979,161	$ 1,086,061	$ 3,921,777	$ 2,061,248
Cost of sales	1,573,327	844,695	3,148,800	1,564,297
Gross profit	405,834	241,366	772,977	496,951
Selling, general and administrative expenses	130,626	53,719	254,277	107,028
Transaction and integration-related costs	8,092	7,709	16,286	7,709
Income (loss) from operations	267,116	179,938	502,414	382,214
Interest Expense	(38,972)	(5,915)	(78,748)	(12,600)
Other income (expense)
Other income (expense), net	(538)	8,181	4,533	10,826
Income before income taxes	227,606	182,204	428,199	380,440
Provision for income taxes	68,188	66,584	124,071	135,884
Net income	159,418	115,620	304,128	244,556
Net income attributable to noncontrolling interests	6,591	4,496	13,111	10,304
Net income attributable to Westlake Chemical Corporation	$ 152,827	$ 111,124	$ 291,017	$ 234,252
Earnings per common share attributable to Westlake Chemical Corporation:
Basic (usd per share)	$ 1.18	$ 0.85	$ 2.24	$ 1.80
Diluted (usd per share)	$ 1.17	$ 0.85	$ 2.23	$ 1.79
Weighted average common shares outstanding:
Basic (in shares)	129,051,227	129,583,224	129,015,507	129,886,594
Diluted (in shares)	129,786,714	129,980,527	129,739,643	130,290,521
Dividends per common share (usd per share)	$ 0.1906	$ 0.1815	$ 0.3812	$ 0.3630