Leases Leases - SPPC - Lease Costs (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 153	$ 296
Operating Lease, Cost	41	82
Finance Lease, Right-of-Use Asset, Amortization	4	8
Finance Lease, Interest Expense	10	21
Lease, Cost	$ 209	$ 410
Operating Lease, Weighted Average Remaining Lease Term	8 years	8 years
Finance Lease, Weighted Average Remaining Lease Term	29 years 1 month 6 days	29 years 1 month 6 days
Operating Lease, Weighted Average Discount Rate, Percent	5.20%	5.20%
Finance Lease, Weighted Average Discount Rate, Percent	8.70%	8.70%
Sierra Pacific Power Company [Member]
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 15	$ 30
Operating Lease, Cost	1	1
Finance Lease, Right-of-Use Asset, Amortization	0	1
Finance Lease, Interest Expense	0	1
Lease, Cost	$ 16	$ 33
Operating Lease, Weighted Average Remaining Lease Term	26 years	26 years
Finance Lease, Weighted Average Remaining Lease Term	23 years	23 years
Operating Lease, Weighted Average Discount Rate, Percent	4.90%	4.90%
Finance Lease, Weighted Average Discount Rate, Percent	7.00%	7.00%