Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 70,014	$ 188,420	$ 314,570	$ 548,888
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	(206)	(22)	(412)	(208)
Amortization of benefits liability	369	692	1,072	2,019
Income tax provision on pension and other post-retirement benefits liability	(60)	(232)	(251)	(621)
Foreign currency translation adjustments	6,453	(1,920)	15,758	(43,746)
Available-for-sale investments
Unrealized holding gains (losses) on investments	1,550	(716)	61,524	3,987
Reclassification of net realized gains to net income	(52,401)	0	(53,720)	(3,795)
Income tax benefit (provision) on available-for-sale investments	18,270	257	(2,805)	(68)
Other comprehensive (loss) income	(26,025)	(1,941)	21,166	(42,432)
Comprehensive income	43,989	186,479	335,736	506,456
Comprehensive income attributable to noncontrolling interests, net of tax of $0 for each of the respective periods presented	4,352	4,816	14,656	13,847
Comprehensive income attributable to Westlake Chemical Corporation	$ 39,637	$ 181,663	$ 321,080	$ 492,609