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Description of Business and Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) plant	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Capitalized interest	$ 3	$ 4	$ 9
Asset Retirement Obligation, Current	1	12
Asset Retirement Obligations, Noncurrent	23	17
Stockholders' equity	$ 8,528	6,578	6,403	$ 6,076
RS Cogen
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Ownership percentage by parent	50.00%
Entergy
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Ownership percentage by noncontrolling owners	50.00%
Minimum
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Deferred Cost, Amortization Period	3 years
Maximum
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Deferred Cost, Amortization Period	6 years
Limited Partner \| IPO \| Subsidiary of Common Parent \| Westlake Chemical OpCo LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Limited partner interest (percent)	77.20%
Subsidiaries [Member] \| Louisiana \| Westlake Chemical OpCo LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of production facilities \| plant	2
Subsidiaries [Member] \| Kentucky \| Westlake Chemical OpCo LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of production facilities \| plant	1
Accumulated Other Comprehensive Income (Loss)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stockholders' equity	$ (36)	$ (64)	$ (74)	$ (62)