Leases Leases - SPPC - Summary (Details) $ in Millions	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 525
Finance Lease, Right-of-Use Asset	504
Total Right-of-Use Asset	1,029
Operating Lease, Liability	577
Finance Lease, Liability	519
Total Lease Liabilities	1,096
Sierra Pacific Power Company [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	17
Finance Lease, Right-of-Use Asset	43
Total Right-of-Use Asset	60
Operating Lease, Liability	17
Finance Lease, Liability	45
Total Lease Liabilities	$ 62