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Commodity Derivatives (Details)
MWh in Millions, MMBTU in Millions, $ in Millions
 3 Months Ended
Mar. 31, 2025
USD ($)
MWh
MMBTU
Mar. 31, 2024
USD ($)
Dec. 31, 2024
MWh
MMBTU
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 $ 12 $ 3  
Cash Flow Hedge Commodity [Member]      
Derivative [Line Items]      
Commodity contracts designated as cash flow hedges $ 0    
Electric Commodity [Member]      
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]      
Derivative, Nonmonetary Notional Amount | MWh [1],[2] 28   38
Natural Gas Commodity      
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]      
Derivative, Nonmonetary Notional Amount | MMBTU [1],[2] 59   77
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 regulatory (assets) and liabilities $ 7 [3] $ 4  
[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.
[3] Other than $2 million of 2025 gains recorded to electric fuel and purchased power, amounts are recorded to cost of natural gas sold and transported. Amounts are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.