Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 157	$ 82
Foreign Currency Translation Adjustment, by Component [Abstract]
Foreign currency translation	(25)	(2)
Income tax provision on foreign currency translation	(7)	0
Other comprehensive loss, net of income taxes	(32)	(2)
Comprehensive income	125	80
Comprehensive income attributable to noncontrolling interests, net of tax of $1 and $1 for the three months ended March 31, 2020 and 2019, respectively	12	10
Comprehensive income attributable to Westlake Chemical Corporation	$ 113	$ 70