Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 24	$ 129	$ 181	$ 211
Foreign Currency Translation Adjustment, by Component [Abstract]
Foreign currency translation	15	15	(10)	13
Income tax provision on foreign currency translation	5	(2)	(2)	(2)
Other comprehensive income (loss), net of income taxes	20	13	(12)	11
Comprehensive income	44	142	169	222
Comprehensive income attributable to noncontrolling interests, net of tax of $0 and $0 for the three months ended June 30, 2020 and 2019; and net of tax of $1 and $1 for the six months ended June 30, 2020 and 2019, respectively	10	9	22	19
Comprehensive income attributable to Westlake Chemical Corporation	$ 34	$ 133	$ 147	$ 203