Leases - SPPC - Other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	$ (152)	$ (153)
Finance Lease, Interest Payment on Liability	(40)	(42)
Finance Lease, Principal Payments	(24)	(19)
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	19	14
Sierra Pacific Power Company [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	(2)	(3)
Finance Lease, Interest Payment on Liability	(6)	(3)
Finance Lease, Principal Payments	(5)	(3)
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 89	$ 5