Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 1,339	$ 420	$ 665
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	19	60	18
Amortization of benefits liability	2	1	3
Income tax provision on pension and other post-retirement benefits liability	(7)	(24)	(6)
Foreign currency translation	124	(34)	(60)
Income tax provision on foreign currency translation	(5)	0	0
Available-for-sale investments
Unrealized holding gains (losses) on investments	0	62	(4)
Reclassification of net realized gains to net income	0	(54)	(4)
Income tax benefit (provision) on available-for-sale investments	0	(3)	3
Other comprehensive income (loss)	133	8	(50)
Comprehensive income	1,472	428	615
Comprehensive income attributable to noncontrolling interests, net of tax of $1, $0 and $0 for 2017, 2016 and 2015, respectively	40	21	19
Comprehensive income attributable to Westlake Chemical Corporation	$ 1,432	$ 407	$ 596