Leases - NPC - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 1999
NPC
Lessee, Lease, Description [Line Items]
Remaining share ownership, transmission tine project	75.00%
ON Line financing lease obligation	$ 253	$ 264
SPPC
Lessee, Lease, Description [Line Items]
Remaining share ownership, transmission tine project	75.00%
Finance lease term			50 years
ON Line financing lease obligation	$ 114	$ 117
ON Line Transmission Line | Nevada Utilities
Lessee, Lease, Description [Line Items]
Utilities aggregate share ownership, transmission line project	25.00%
ON Line Transmission Line | NPC
Lessee, Lease, Description [Line Items]
Utilities aggregate share ownership, transmission line project	75.00%
Finance lease term	41 years
ON Line Transmission Line | SPPC
Lessee, Lease, Description [Line Items]
Utilities aggregate share ownership, transmission line project	25.00%
Finance lease term	41 years