Commitments and Contingencies - SPPC - Commitments Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	$ 2,400
Contractual Obligation, Due in Next Twelve Months	4,631
Contractual Obligation, Due in Second Year	2,458
Contractual Obligation, Due in Third Year	1,614
Contractual Obligation, Due in Fourth Year	1,467
Contractual Obligation, Due in Fifth Year	1,421
Contractual Obligation, Due after Fifth Year	17,467
Contractual Obligation	29,058
Fuel, capacity and transmission contract commitments [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	2,218
Purchase Obligation, Due in Second Year	1,527
Purchase Obligation, Due in Third Year	1,193
Purchase Obligation, Due in Fourth Year	1,093
Purchase Obligation, Due in Fifth Year	1,088
Purchase Obligation, Due after Fifth Year	13,584
Purchase Obligation	20,703
Easements [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	62
Purchase Obligation, Due in Second Year	68
Purchase Obligation, Due in Third Year	70
Purchase Obligation, Due in Fourth Year	72
Purchase Obligation, Due in Fifth Year	70
Purchase Obligation, Due after Fifth Year	2,259
Purchase Obligation	2,601
Maintenance, service and other contracts [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	669
Purchase Obligation, Due in Second Year	342
Purchase Obligation, Due in Third Year	324
Purchase Obligation, Due in Fourth Year	300
Purchase Obligation, Due in Fifth Year	255
Purchase Obligation, Due after Fifth Year	1,624
Purchase Obligation	3,514
Sierra Pacific Power Company [Member]
Contractual Obligation [Line Items]
Contractual Obligation, Due in Next Twelve Months	274
Contractual Obligation, Due in Second Year	219
Contractual Obligation, Due in Third Year	164
Contractual Obligation, Due in Fourth Year	129
Contractual Obligation, Due in Fifth Year	128
Contractual Obligation, Due after Fifth Year	1,823
Contractual Obligation	2,737
Easement, Expense	2	$ 2	$ 2
Sierra Pacific Power Company [Member] | Fuel, capacity and transmission contract commitments [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	260
Purchase Obligation, Due in Second Year	198
Purchase Obligation, Due in Third Year	114
Purchase Obligation, Due in Fourth Year	84
Purchase Obligation, Due in Fifth Year	83
Purchase Obligation, Due after Fifth Year	863
Purchase Obligation	1,602
Sierra Pacific Power Company [Member] | Fuel, capacity and transmission contract commitments, Not commercially operable [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	1
Purchase Obligation, Due in Second Year	11
Purchase Obligation, Due in Third Year	41
Purchase Obligation, Due in Fourth Year	41
Purchase Obligation, Due in Fifth Year	42
Purchase Obligation, Due after Fifth Year	921
Purchase Obligation	1,057
Sierra Pacific Power Company [Member] | Easements [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	2
Purchase Obligation, Due in Second Year	2
Purchase Obligation, Due in Third Year	2
Purchase Obligation, Due in Fourth Year	2
Purchase Obligation, Due in Fifth Year	2
Purchase Obligation, Due after Fifth Year	30
Purchase Obligation	40
Sierra Pacific Power Company [Member] | Maintenance, service and other contracts [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	11
Purchase Obligation, Due in Second Year	8
Purchase Obligation, Due in Third Year	7
Purchase Obligation, Due in Fourth Year	2
Purchase Obligation, Due in Fifth Year	1
Purchase Obligation, Due after Fifth Year	9
Purchase Obligation	$ 38