Risk Management and Hedging Activities - PAC - Balance Sheet Location (Details) - PAC - Commodity derivatives - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Total	$ 195	$ 53
Cash collateral payable	(17)	5
Total derivatives - net basis	178	58
Derivative Contracts - Current Assets
Derivatives, Fair Value [Line Items]
Total	162	76
Cash collateral payable	(17)	0
Total derivatives - net basis	145	76
Other Assets
Derivatives, Fair Value [Line Items]
Total	37	20
Cash collateral payable	0	0
Total derivatives - net basis	37	20
Other Current Liabilities
Derivatives, Fair Value [Line Items]
Total	(3)	(36)
Cash collateral payable	0	5
Total derivatives - net basis	(3)	(31)
Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Total	(1)	(7)
Cash collateral payable	0	0
Total derivatives - net basis	(1)	(7)
Not Designated as Hedging
Derivatives, Fair Value [Line Items]
Derivative asset, gross	207	104
Derivative liability	(12)	(51)
Total	195	53
Net regulatory asset (liability) on derivative contracts	(195)	(53)	$ 0	$ 17
Not Designated as Hedging | Derivative Contracts - Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross	165	81
Derivative liability	(3)	(5)
Total	162	76
Not Designated as Hedging | Other Assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross	37	21
Derivative liability	0	(1)
Total	37	20
Not Designated as Hedging | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative asset, gross	6	2
Derivative liability	(9)	(38)
Total	(3)	(36)
Not Designated as Hedging | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative asset, gross	(1)	0
Derivative liability	0	(7)
Total	$ (1)	$ (7)