Leases Leases - SPPC - Summary (Details) $ in Millions	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 553
Finance Lease, Right-of-Use Asset	509
Total Right-of-Use Asset	1,062
Operating Lease, Liability	597
Finance Lease, Liability	523
Total Lease Liabilities	1,120
Sierra Pacific Power Company [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	19
Finance Lease, Right-of-Use Asset	39
Total Right-of-Use Asset	58
Operating Lease, Liability	19
Finance Lease, Liability	40
Total Lease Liabilities	$ 59