Leases Leases - SPPC - Lease Costs (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 623
Operating Lease, Cost	170
Finance Lease, Right-of-Use Asset, Amortization	16
Finance Lease, Interest Expense	41
Lease, Cost	$ 857
Operating Lease, Weighted Average Remaining Lease Term	7 years 7 months 21 days
Finance Lease, Weighted Average Remaining Lease Term	28 years 10 months 2 days
Operating Lease, Weighted Average Discount Rate, Percent	5.20%
Finance Lease, Weighted Average Discount Rate, Percent	8.60%
Sierra Pacific Power Company [Member]
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 69
Operating Lease, Cost	1
Finance Lease, Right-of-Use Asset, Amortization	2
Finance Lease, Interest Expense	2
Lease, Cost	$ 74
Operating Lease, Weighted Average Remaining Lease Term	26 years 3 months 26 days
Finance Lease, Weighted Average Remaining Lease Term	20 years 10 months 21 days
Operating Lease, Weighted Average Discount Rate, Percent	5.00%
Finance Lease, Weighted Average Discount Rate, Percent	7.10%