Leases Leases - NPC - Summary (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
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
Nevada Power Company [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	13
Finance Lease, Right-of-Use Asset	441	$ 450
Total Right-of-Use Asset	454
Operating Lease, Liability	17
Finance Lease, Liability	454
Total Lease Liabilities	$ 471