Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 188,420	$ 170,156	$ 548,888	$ 497,631
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	(22)	(31)	(208)	(62)
Amortization of benefits liability	692	240	2,019	685
Income tax provision on pension and other post-retirement benefits liability	(232)	(81)	(621)	(240)
Foreign currency translation adjustments	(1,920)	(37,792)	(43,746)	(37,882)
Available-for-sale investments
Unrealized holding (losses) gains on investments	(716)	2,129	3,987	6,960
Reclassification of net realized gain to net income	0	0	(3,795)	(1,212)
Income tax benefit (provision) on available- for-sale investments	257	(766)	(68)	(2,066)
Other comprehensive loss	(1,941)	(36,301)	(42,432)	(33,817)
Comprehensive income	186,479	133,855	506,456	463,814
Comprehensive income attributable to noncontrolling interests, net of tax	4,816	2,399	13,847	2,399
Comprehensive income attributable to Westlake Chemical Corporation	$ 181,663	$ 131,456	$ 492,609	$ 461,415