Interest Rate Derivative (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2022		Jun. 30, 2021		Jun. 30, 2022		Jun. 30, 2021
Other Derivative Instruments
Interest Rate Derivatives [Abstract]
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)		1		(1)		11
Pre-tax gains (losses) recognized during the period in income		5		2		1		30
Designated as Hedging Instrument [Member] | Cash Flow Hedges
Interest Rate Derivatives [Abstract]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net								1
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)								0
Pre-tax gains (losses) recognized during the period in income								0
Interest Rate Derivatives
Interest Rate Derivatives [Abstract]
Amount or interest rate derivatives expected to be reclassified		1				1
Derivative Liability, Notional Amount		0				0
Commodity Trading Contract | Other Derivative Instruments
Interest Rate Derivatives [Abstract]
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)		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
Interest Rate Derivatives [Abstract]
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	[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
Interest Rate Derivatives [Abstract]
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)	[4]	(1)	[3]
Pre-tax gains (losses) recognized during the period in income	[3],[4]					$ (5)		(3)
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedges
Interest Rate Derivatives [Abstract]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[5]							1
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)								0
Pre-tax gains (losses) recognized during the period in income								$ 0

[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.

[5] Recorded to interest charges.