Risk Management and Hedging Activities - NPC - Balance Sheet Location (Details) - NPC - Commodity derivatives - Not Designated as Hedging - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Commodity liabilities	$ (101)	$ (68)
Net regulatory asset (liability) on derivative contracts	101	68
Other Current Assets
Derivatives, Fair Value [Line Items]
Commodity liabilities	0	0
Derivative Contracts - Current Liabilities
Derivatives, Fair Value [Line Items]
Commodity liabilities	(91)	(62)
Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Commodity liabilities	$ (10)	$ (6)