Leases Leases - SPPC - Lease Costs (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 156	$ 453
Operating Lease, Cost	43	127
Finance Lease, Right-of-Use Asset, Amortization	4	12
Finance Lease, Interest Expense	10	31
Lease, Cost	$ 215	$ 629
Operating Lease, Weighted Average Remaining Lease Term	7 years 9 months 18 days	7 years 9 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	29 years 3 months 18 days	29 years 3 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	5.20%	5.20%
Finance Lease, Weighted Average Discount Rate, Percent	8.60%	8.60%
Sierra Pacific Power Company [Member]
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 21	$ 51
Operating Lease, Cost	0	1
Finance Lease, Right-of-Use Asset, Amortization	0	1
Finance Lease, Interest Expense	1	2
Lease, Cost	$ 22	$ 55
Operating Lease, Weighted Average Remaining Lease Term	26 years	26 years
Finance Lease, Weighted Average Remaining Lease Term	22 years 1 month 6 days	22 years 1 month 6 days
Operating Lease, Weighted Average Discount Rate, Percent	5.00%	5.00%
Finance Lease, Weighted Average Discount Rate, Percent	7.20%	7.20%