Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 210,061	$ 169,443	$ 360,468	$ 327,475
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	186	31	186	31
Amortization of benefits liability	675	226	1,327	445
Income tax provision on pension and other post-retirement benefits liability	(164)	(75)	(389)	(159)
Foreign currency translation adjustments	17,872	808	(41,826)	(90)
Available-for-sale investments
Unrealized holding gains on investments	3,077	2,364	4,703	4,831
Reclassification of net realized gain to net income	(3,795)	(1,237)	(3,795)	(1,212)
Income tax benefit (provision) on available- for-sale investments	259	(405)	(325)	(1,300)
Other comprehensive income (loss)	17,738	1,650	(40,491)	2,484
Comprehensive income	227,799	171,093	319,977	329,959
Comprehensive income attributable to noncontrolling interests, net of tax	4,966	0	9,031	0
Comprehensive income attributable to Westlake Chemical Corporation	$ 222,833	$ 171,093	$ 310,946	$ 329,959