Leases - SPPC - Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 592	$ 623
Operating	151	170
Amortization	18	16
Finance Lease, Interest Expense	40	41
Lease, Cost	$ 821	$ 857
Operating Lease, Weighted Average Remaining Lease Term	7 years 4 months 24 days	7 years 7 months 6 days
Finance Lease, Weighted Average Remaining Lease Term	27 years 6 months	28 years 9 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	4.50%	5.20%
Finance Lease, Weighted Average Discount Rate, Percent	8.50%	8.60%
Sierra Pacific Power Company [Member]
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 78	$ 69
Operating	2	1
Amortization	4	2
Finance Lease, Interest Expense	9	2
Lease, Cost	$ 93	$ 74
Operating Lease, Weighted Average Remaining Lease Term	27 years 2 months 12 days	26 years 3 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	27 years 9 months 18 days	20 years 10 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	5.00%	5.00%
Finance Lease, Weighted Average Discount Rate, Percent	8.10%	7.10%