Earnings and Dividends per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings and Dividends Per Share [Abstract]
Net income attributable to Westlake Corporation	$ 108	$ 285	$ 595	$ 976
Net income attributable to participating securities	(1)	(2)	(3)	(5)
Net income attributable to common stockholders	$ 107	$ 283	$ 592	$ 971