Future year net unrealized gain/loss recorded at balance sheet date expected to become realized (Details) $ in Millions	Dec. 31, 2022 USD ($)
Electricity [Member]
Commodity contracts:
Other Commitment, Due in Next Twelve Months	$ (19)
Other Commitment, Due in Second Year	10
Other Commitment, Due in Third Year	21
Other Commitment, Due in Fourth Year	(3)
Other Commitment, Due in Fifth Year	(3)
Other Commitment, Due after Fifth Year	(16)
Total	(10)
Natural Gas [Member]
Commodity contracts:
Other Commitment, Due in Next Twelve Months	(177)
Other Commitment, Due in Second Year	8
Other Commitment, Due in Third Year	2
Other Commitment, Due in Fourth Year	(3)
Other Commitment, Due in Fifth Year	0
Other Commitment, Due after Fifth Year	0
Total	(184)
Unrealized Gain Loss On Derivatives [Member]
Commodity contracts:
Other Commitment, Due in Next Twelve Months	(196)
Other Commitment, Due in Second Year	2
Other Commitment, Due in Third Year	19
Other Commitment, Due in Fourth Year	0
Other Commitment, Due in Fifth Year	(3)
Other Commitment, Due after Fifth Year	(16)
Total	$ (194)