Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at start of period	$ (36)	$ (64)
Balance at end of period	(89)	(36)
Pension and Other Post-Retirement Benefits Liability, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at start of period	20	(24)
Net other comprehensive income (loss) attributable to Westlake Corporation	32	44
Balance at end of period	52	20
Cumulative Foreign Currency Exchange, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at start of period	(56)	(40)
Net other comprehensive income (loss) attributable to Westlake Corporation	(85)	(16)
Balance at end of period	(141)	(56)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net other comprehensive income (loss) attributable to Westlake Corporation	$ (53)	$ 28