Leases - SPPC - Maturity Table (Details) - USD ($) $ in Millions	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2020	Aug. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 152		$ 152
Lessee, Operating Lease, Liability, Payments, Due Year Two	125		125
Lessee, Operating Lease, Liability, Payments, Due Year Three	93		93
Lessee, Operating Lease, Liability, Payments, Due Year Four	66		66
Lessee, Operating Lease, Liability, Payments, Due Year Five	50		50
Lessee, Operating Lease, Liability, Payments, Due after Year Five	199		199
Lessee, Operating Lease, Liability, Payments, Due	685		685
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(116)		(116)
Operating Lease, Liability	569		569
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, Payments, Due Next Twelve Months	81		81
Finance Lease, Liability, Payments, Due Year Two	74		74
Finance Lease, Liability, Payments, Due Year Three	63		63
Finance Lease, Liability, Payments, Due Year Four	63		63
Finance Lease, Liability, Payments, Due Year Five	62		62
Finance Lease, Liability, Payments, Due after Year Five	673		673
Finance Lease, Liability, Payment, Due	1,016		1,016
Finance Lease, Liability, Undiscounted Excess Amount	(502)		(502)
Finance Lease, Liability	514		514
Lease, Liability, Payments, Due Next Twelve Months	233		233
Lease, Liability, Payments, Due Year Two	199		199
Lease, Liability, Payments, Due Year Three	156		156
Lease, Liability, Payments, Due Year Four	129		129
Lease, Liability, Payments, Due Year Five	112		112
Lease, Liability, Payments, Due after Year Five	872		872
Lease, Liability, Payments, Due	1,701		1,701
Lease, Liability, Undiscounted Excess Amount	(618)		(618)
Total Lease Liabilities	1,083		1,083	$ 1,096
Sierra Pacific Power Company [Member]
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	2		2
Lessee, Operating Lease, Liability, Payments, Due Year Two	1		1
Lessee, Operating Lease, Liability, Payments, Due Year Three	1		1
Lessee, Operating Lease, Liability, Payments, Due Year Four	1		1
Lessee, Operating Lease, Liability, Payments, Due Year Five	1		1
Lessee, Operating Lease, Liability, Payments, Due after Year Five	25		25
Lessee, Operating Lease, Liability, Payments, Due	31		31
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(15)		(15)
Operating Lease, Liability	16		16	17
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, Payments, Due Next Twelve Months	17		17
Finance Lease, Liability, Payments, Due Year Two	17		17
Finance Lease, Liability, Payments, Due Year Three	17		17
Finance Lease, Liability, Payments, Due Year Four	16		16
Finance Lease, Liability, Payments, Due Year Five	16		16
Finance Lease, Liability, Payments, Due after Year Five	170		170
Finance Lease, Liability, Payment, Due	253		253
Finance Lease, Liability, Undiscounted Excess Amount	(123)		(123)
Finance Lease, Liability	130		130	45
Lease, Liability, Payments, Due Next Twelve Months	19		19
Lease, Liability, Payments, Due Year Two	18		18
Lease, Liability, Payments, Due Year Three	18		18
Lease, Liability, Payments, Due Year Four	17		17
Lease, Liability, Payments, Due Year Five	17		17
Lease, Liability, Payments, Due after Year Five	195		195
Lease, Liability, Payments, Due	284		284
Lease, Liability, Undiscounted Excess Amount	(138)		(138)
Total Lease Liabilities	146		$ 146	62
Remaining Share Transmission Line Project			75.00%
ON Line Financing Lease Obligation	122		$ 122	35
Nevada Power Company [Member]
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	3		3
Lessee, Operating Lease, Liability, Payments, Due Year Two	3		3
Lessee, Operating Lease, Liability, Payments, Due Year Three	2		2
Lessee, Operating Lease, Liability, Payments, Due Year Four	3		3
Lessee, Operating Lease, Liability, Payments, Due Year Five	3		3
Lessee, Operating Lease, Liability, Payments, Due after Year Five	4		4
Lessee, Operating Lease, Liability, Payments, Due	18		18
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(3)		(3)
Operating Lease, Liability	15		15	17
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, Payments, Due Next Twelve Months	56		56
Finance Lease, Liability, Payments, Due Year Two	54		54
Finance Lease, Liability, Payments, Due Year Three	43		43
Finance Lease, Liability, Payments, Due Year Four	43		43
Finance Lease, Liability, Payments, Due Year Five	43		43
Finance Lease, Liability, Payments, Due after Year Five	491		491
Finance Lease, Liability, Payment, Due	730		730
Finance Lease, Liability, Undiscounted Excess Amount	(369)		(369)
Finance Lease, Liability	361		361	454
Lease, Liability, Payments, Due Next Twelve Months	59		59
Lease, Liability, Payments, Due Year Two	57		57
Lease, Liability, Payments, Due Year Three	45		45
Lease, Liability, Payments, Due Year Four	46		46
Lease, Liability, Payments, Due Year Five	46		46
Lease, Liability, Payments, Due after Year Five	495		495
Lease, Liability, Payments, Due	748		748
Lease, Liability, Undiscounted Excess Amount	(372)		(372)
Total Lease Liabilities	376		$ 376	471
Remaining Share Transmission Line Project			75.00%
ON Line Financing Lease Obligation	$ 295		$ 295	$ 385
ON Line deferrals | Sierra Pacific Power Company [Member]
Finance Lease, Liability, Payment, Due [Abstract]
Utilities Aggregate Share Transmission Line Project	25.00%	5.00%	25.00%
Lessee, Finance Lease, Term of Contract	41 years		41 years
ON Line deferrals | Nevada Power Company [Member]
Finance Lease, Liability, Payment, Due [Abstract]
Utilities Aggregate Share Transmission Line Project	75.00%	95.00%	25.00%
Lessee, Finance Lease, Term of Contract	41 years		41 years