Earnings and Dividends per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings and Dividends Per Share [Abstract]
Net income attributable to Westlake Corporation	$ 174	$ 394
Net income attributable to participating securities	(1)	(2)
Net income attributable to common shareholders	$ 173	$ 392