Commitments (Long-Term Purchase Commitments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Electricity Purchase Contracts
Long-Term Purchase Commitment [Line Items]
Purchases Under Long Term Contracts	$ 709	$ 756	$ 1,597
Purchase Obligation, Due in Next Twelve Months	714
Purchase Obligation, Due in Second Year	570
Purchase Obligation, Due in Third Year	551
Purchase Obligation, Due in Fourth Year	546
Purchase Obligation, Due in Fifth Year	529
Future Commitments Thereafter	5,894
Future Commitments Total	8,804
Fuel Purchase Contracts
Long-Term Purchase Commitment [Line Items]
Purchases Under Long Term Contracts	2,070	1,573	1,824
Purchase Obligation, Due in Next Twelve Months	1,882
Purchase Obligation, Due in Second Year	1,157
Purchase Obligation, Due in Third Year	881
Purchase Obligation, Due in Fourth Year	837
Purchase Obligation, Due in Fifth Year	639
Future Commitments Thereafter	113
Future Commitments Total	5,509
Other Purchase Contracts
Long-Term Purchase Commitment [Line Items]
Purchases Under Long Term Contracts	1,261	$ 1,506	$ 1,684
Purchase Obligation, Due in Next Twelve Months	5,896
Purchase Obligation, Due in Second Year	617
Purchase Obligation, Due in Third Year	322
Purchase Obligation, Due in Fourth Year	230
Purchase Obligation, Due in Fifth Year	181
Future Commitments Thereafter	1,585
Future Commitments Total	$ 8,831