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 [Abstract]
Fair value hedges		$ 0	$ 0	$ 0	$ 0
Other Derivative Instruments
Impact of Derivative Activity [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0	0
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		(28)	0	(135)	103
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0	0	0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		15	6	120	(27)
Pre-tax gains (losses) recognized during the period in income		0	13	(25)	4
Other Derivative Instruments | Electric Commodity
Impact of Derivative Activity [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0	0
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		(23)	6	(134)	106
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0	0	0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)	[1]	15	6	109	(31)
Pre-tax gains (losses) recognized during the period in income		0	0	0	0
Other Derivative Instruments | Natural Gas Commodity
Impact of Derivative Activity [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0	0
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		(5)	(6)	(1)	(3)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net				0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)	[2]			11	4
Pre-tax gains (losses) recognized during the period in income	[2],[3]			(19)	(17)
Other Derivative Instruments | Commodity Trading
Impact of Derivative Activity [Abstract]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			0	0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)			0	0	0
Pre-tax gains (losses) recognized during the period in income	[4]		13	(6)	21
Designated as Hedging Instrument | Cash Flow Hedges
Impact of Derivative Activity [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		4		15	21
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		0		0	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		1	1	4	5
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		0	0	0	0
Designated as Hedging Instrument | Cash Flow Hedges | Interest Rate
Impact of Derivative Activity [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		4		15	21
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		0		0	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[5]	1	1	4	5
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		$ 0	$ 0	$ 0	$ 0
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		7		7
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		6		6
Wholesale, trading and non-trading commodity credit exposure for the most significant counterparties		$ 62		$ 62
Percentage of wholesale, trading and non-trading commodity credit exposure for the most significant counterparties (in hundredths)		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		3		3
Wholesale, trading and non-trading commodity credit exposure for the most significant counterparties		$ 60		$ 60
Percentage of wholesale, trading and non-trading commodity credit exposure for the most significant counterparties (in hundredths)		29.00%		29.00%
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		$ 44		$ 44
Percentage of wholesale, trading and non-trading commodity credit exposure for the most significant counterparties (in hundredths)		22.00%		22.00%

[1] 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.

[2] 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.

[3] Relates primarily to option premium amortization.

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

[5] Recorded to interest charges.