Risk Management and Hedging Activities - NPC - Balance Sheet Location (Details) - NPC - Commodity derivatives - Not Designated as Hedging - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Derivatives, Fair Value [Line Items]
Commodity liabilities	$ (49)	$ (41)
Net regulatory asset (liability) on derivative contracts	49	41
Balance Sheet Location [Axis]: us-gaap:LiabilitiesCurrent
Derivatives, Fair Value [Line Items]
Commodity liabilities	(31)	(27)
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Derivatives, Fair Value [Line Items]
Commodity liabilities	$ (18)	$ (14)

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and elected not to be offset.