Commitments and Contingencies, Fuel Contracts (Details) $ in Millions	Dec. 31, 2023 USD ($)
Coal
Unrecorded Unconditional Purchase Obligation, to be Paid, Year One	$ 143
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two	74
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three	39
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four	35
2028	0
Thereafter	0
Total	291
Natural Gas Supply
Unrecorded Unconditional Purchase Obligation, to be Paid, Year One	221
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two	12
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three	0
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four	0
2028	0
Thereafter	0
Total	233
Natural Gas Storage and Transportation
Unrecorded Unconditional Purchase Obligation, to be Paid, Year One	108
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two	105
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three	105
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four	105
2028	62
Thereafter	382
Total	$ 867