Risk Management Fair values of price risk management assets and liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Current Assets, Commodity Contracts:
Electricity	$ 40	$ 16
Natural gas	181	86
Total current derivative assets	221	102
Noncurrent Assets, Commodity Contracts: [Abstract]
Commodity Contract Asset, Noncurrent, Electricity	10	1
Commodity Contract Asset, Noncurrent, Natural Gas	80	34
Derivative Asset, Noncurrent	90	35
Total derivative assets	311	137
Current Liabilities, Commodity Contracts: [Abstract]
Electricity	51	36
Natural gas	4	11
Total current derivative liabilities	55	47
Noncurrent Liabilities, Commodity Contracts: [Abstract]
Electricity	63	87
Natural gas	4	3
Total noncurrent derivative liabilities	67	90
Total derivative liabilities	$ 122	$ 137