Leases Leases - NPC - Other (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	$ (106)
Finance Lease, Interest Payment on Liability	(32)
Finance Lease, Principal Payments	(14)
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	12
Nevada Power Company [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	(2)
Finance Lease, Interest Payment on Liability	(29)
Finance Lease, Principal Payments	(11)
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 8