Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net sales	$ 2,108,889	$ 1,279,028	$ 6,030,666	$ 3,340,276
Cost of sales	1,610,837	1,076,895	4,759,637	2,641,192
Gross profit	498,052	202,133	1,271,029	699,084
Selling, general and administrative expenses	125,642	72,729	379,919	179,757
Transaction and integration-related costs	6,663	82,841	22,949	90,550
Income (loss) from operations	365,747	46,563	868,161	428,777
Other income (expense)
Interest expense	(40,036)	(24,366)	(118,784)	(36,966)
Nonoperating Income (Expense)	2,058	41,265	6,591	52,091
Income before income taxes	327,769	63,462	755,968	443,902
Provision for (benefit from) income taxes	108,619	(6,552)	232,690	129,332
Net income	219,150	70,014	523,278	314,570
Net income attributable to noncontrolling interests	8,318	4,352	21,429	14,656
Net income attributable to Westlake Chemical Corporation	$ 210,832	$ 65,662	$ 501,849	$ 299,914
Earnings per common share attributable to Westlake Chemical Corporation:
Basic (usd per share)	$ 1.62	$ 0.51	$ 3.87	$ 2.31
Diluted (usd per share)	$ 1.61	$ 0.51	$ 3.85	$ 2.29
Weighted average common shares outstanding:
Basic (in shares)	129,069,186	128,793,661	129,033,597	129,519,577
Diluted (in shares)	129,888,968	129,379,956	129,789,965	130,103,897
Dividends per common share (usd per share)	$ 0.2100	$ 0.1906	$ 0.5912	$ 0.5536