Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 115,620	$ 210,061	$ 244,556	$ 360,468
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	(206)	(186)	(206)	(186)
Amortization of benefits liability	369	675	703	1,327
Income tax provision on pension and other post-retirement benefits liability	(63)	(164)	(191)	(389)
Foreign currency translation adjustments	(13,500)	17,872	9,305	(41,826)
Available-for-sale investments
Unrealized holding gains on investments	35,545	3,077	59,973	4,703
Reclassification of net realized gains to net income	(1,267)	(3,795)	(1,319)	(3,795)
Income tax (provision) benefit on available-for-sale investments	(12,316)	259	(21,074)	(325)
Other comprehensive income (loss)	8,562	17,738	47,191	(40,491)
Comprehensive income	124,182	227,799	291,747	319,977
Comprehensive income attributable to noncontrolling interests, net of tax	4,496	4,966	10,304	9,031
Comprehensive income attributable to Westlake Chemical Corporation	$ 119,686	$ 222,833	$ 281,443	$ 310,946