Risk Management and Hedging Activities - NPC - Balance Sheet Location (Details) - NPC - Commodity derivatives - Not designated as hedging contracts - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Derivative liability, not subject to master netting arrangement	$ (57)	$ (68)
Net regulatory asset (liability) on derivative contracts	57	68
Other current assets
Derivatives, Fair Value [Line Items]
Derivative liability, not subject to master netting arrangement	0	0
Derivative contracts, current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, not subject to master netting arrangement	(53)	(62)
Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, not subject to master netting arrangement	$ (4)	$ (6)