Consideration of Credit Risk and Concentrations (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023 USD ($) Counterparty	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Counterparty	Sep. 30, 2022 USD ($)
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		(22)	18	(48)	26
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)		(10)	2	(31)	3
Pre-tax gains (losses) recognized during the period in income		(2)	11	(8)	12
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0	0
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	[1]	(2)	11	(3)	17
Electric 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	0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)	[2]	10	(2)	(31)	5
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)				0	2	[3]
Pre-tax gains (losses) recognized during the period in income	[3],[4]			(5)	(5)
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		(3)	(2)	(1)
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0
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		$ (19)	$ 20	(47)	$ 26
Interest Rate Risk | 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				0
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss				$ 5
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		4		4
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 26		$ 26
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		27.00%		27.00%
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		4		4
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 26		$ 26
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		27.00%		27.00%
Credit Concentration Risk | Internal Investment Grade [Member] | Minimum [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		2		2
Credit Concentration Risk | External Credit Rating, Non Investment Grade [Member]
Derivative [Line Items]
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 45		$ 45
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		45.00%		45.00%

[1] Recorded to electric revenues. Presented amounts do not reflect non-derivative transactions or margin sharing with customers.

[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. 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.