Future year net unrealized gain/loss recorded at balance sheet date expected to become realized (Details) $ in Millions	Dec. 31, 2021 USD ($)
Electricity [Member]
Commodity contracts:
Other Commitment, Due in Next Twelve Months	$ (20)
Other Commitment, Due in Second Year	(2)
Other Commitment, Due in Third Year	(3)
Other Commitment, Due in Fourth Year	4
Other Commitment, Due in Fifth Year	5
Other Commitment, Due after Fifth Year	72
Total	(106)
Natural Gas [Member]
Commodity contracts:
Other Commitment, Due in Next Twelve Months	(76)
Other Commitment, Due in Second Year	(26)
Other Commitment, Due in Third Year	(4)
Other Commitment, Due in Fourth Year	0
Other Commitment, Due in Fifth Year	0
Other Commitment, Due after Fifth Year	0
Total	(106)
Unrealized Gain Loss On Derivatives [Member]
Commodity contracts:
Other Commitment, Due in Next Twelve Months	(56)
Other Commitment, Due in Second Year	(24)
Other Commitment, Due in Third Year	(1)
Other Commitment, Due in Fourth Year	4
Other Commitment, Due in Fifth Year	5
Other Commitment, Due after Fifth Year	72
Total	$ 0