Commodity Derivatives (Details) MWh in Millions, MMBTU in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023 USD ($) MWh MMBTU	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) MWh MMBTU	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) MMBTU MWh
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Miscellaneous investments		$ 49		$ 49		$ 48
Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [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		(22)	18	(48)	26
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0	0	0	0
Designated as Hedging Instrument [Member] | Cash Flow Hedges
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities				0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		1		1
Cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges		$ 0		$ 0
Electric commodity
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Derivative, Nonmonetary Notional amount | MWh	[1],[2]	53		53		44
Electric commodity | Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		$ (19)	20	$ (47)	26
Natural Gas Commodity
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Derivative, Nonmonetary Notional amount | MMBTU	[1],[2]	76		76		88
Natural Gas Commodity | Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net				$ 0	0
Commodity Trading Contract | Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		$ 0	0	0	0
Electric Commodity | Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0	0	0	$ 0
Interest Rate Risk | Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss				5
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities				0
Natural gas commodity | Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		$ (3)	$ (2)	$ (1)

[1] Not reflective of net positions in the underlying commodities.

[2] Notional amounts for options included on a gross basis but weighted for the probability of exercise.