Consideration of Credit Risk and Concentrations (Details) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2022 USD ($) Counterparty		Jun. 30, 2021 USD ($)		Jun. 30, 2022 USD ($) Counterparty		Jun. 30, 2021 USD ($)
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Fair Value Hedges, Net		$ 0		$ 0		$ 0		$ 0
Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		6		4		8		5
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss		0		0		0		0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		1		(1)		1		(11)
Pre-tax gains (losses) recognized during the period in income		5		2		1		30
Commodity Trading Contract | Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss		0		0		0		0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		0		0		0		0
Pre-tax gains (losses) recognized during the period in income		5	[1]	2	[2]	6	[2]	33	[1]
Electric Commodity | Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities						6		3
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss		0		0		0		0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		(1)	[2]	(1)	[3]	3	[3]	(12)	[2]
Pre-tax gains (losses) recognized during the period in income		0		0		0		0
Natural Gas Commodity | Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss						0		0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)						2	[4]	1	[3]
Pre-tax gains (losses) recognized during the period in income	[3],[4]					(5)		(3)
Natural gas commodity | Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		(1)		1		$ 2		$ 2
Electric commodity | Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		$ 7		$ 3
Credit Concentration Risk
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		10				10
Credit Concentration Risk | Municipal or Cooperative Entities or Other Utilities [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		4				4
Credit Concentration Risk | External Credit Rating, Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		8				8
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 33				$ 33
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		31.00%				31.00%
Credit Concentration Risk | Internal Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		1				1
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 24				$ 24
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		23.00%				23.00%
Credit Concentration Risk | External Credit Rating, Non Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		1				1
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 47				$ 47
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		45.00%				45.00%

[1] Recorded to electric operating revenues. Portions of these gains and losses are subject to sharing with electric customers through margin-sharing mechanisms and deducted from gross revenue, as appropriate.

[2] Recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate. All FTR settlements are shared with customers and do not have a material impact on net income. Presented amounts reflect changes in fair value between auction and settlement dates, but exclude the original auction fair value.

[3] Recorded to cost of natural gas sold and transported. These losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.

[4] Relates primarily to option premium amortization.