Risk Management and Hedging Activities - NPC - Derivative Contract Volumes (Details) - NPC - Commodity derivatives MWh in Millions, Dth in Millions	Dec. 31, 2022 MWh Dth	Dec. 31, 2021 Dth MWh
Electricity purchases, net
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, nonmonetary notional amount | MWh	2	1
Natural gas purchases
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, nonmonetary notional amount | Dth	109	119