Earnings and Dividends per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings and Dividends Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 858	$ 522	$ 1,614	$ 764
Net income attributable to participating securities	5	2	9	4
Net income attributable to common shareholders	$ 853	$ 520	$ 1,605	$ 760