Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net sales	$ 1,942,616	$ 975,187
Cost of sales	1,575,473	719,602
Gross profit	367,143	255,585
Selling, general and administrative expenses	123,651	53,309
Transaction and integration-related costs	8,194	0
Income from operations	235,298	202,276
Other income (expense)
Interest expense	(39,776)	(6,685)
Other income, net	5,071	2,645
Income before income taxes	200,593	198,236
Provision for income taxes	55,883	69,300
Net income	144,710	128,936
Net income attributable to noncontrolling interests	6,520	5,808
Net income attributable to Westlake Chemical Corporation	$ 138,190	$ 123,128
Earnings per common share attributable to Westlake Chemical Corporation:
Basic (usd per share)	$ 1.07	$ 0.94
Diluted (usd per share)	$ 1.06	$ 0.94
Weighted average common shares outstanding:
Basic (in shares)	128,979,357	130,189,964
Diluted (in shares)	129,692,015	130,600,514
Dividends per common share (usd per share)	$ 0.1906	$ 0.1815