Leases Leases - NPC - Maturity Table (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year		$ 38
Lessee, Operating Lease, Liability, Payments, Due Year Two		139
Lessee, Operating Lease, Liability, Payments, Due Year Three		118
Lessee, Operating Lease, Liability, Payments, Due Year Four		96
Lessee, Operating Lease, Liability, Payments, Due Year Five		68
Lessee, Operating Lease, Liability, Payments, Due after Year Five		241
Lessee, Operating Lease, Liability, Payments, Due		700
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(126)
Operating Lease, Liability		574
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, Payments, Remainder of Fiscal Year		16
Finance Lease, Liability, Payments, Due Year Two		70
Finance Lease, Liability, Payments, Due Year Three		76
Finance Lease, Liability, Payments, Due Year Four		69
Finance Lease, Liability, Payments, Due Year Five		58
Finance Lease, Liability, Payments, Due after Year Five		779
Finance Lease, Liability, Payment, Due		1,068
Finance Lease, Liability, Undiscounted Excess Amount		(551)
Finance Lease, Liability		517
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	[1]		$ 147
Operating Leases, Future Minimum Payments, Due in Two Years	[1]		128
Operating Leases, Future Minimum Payments, Due in Three Years	[1]		110
Operating Leases, Future Minimum Payments, Due in Four Years	[1]		87
Operating Leases, Future Minimum Payments, Due in Five Years	[1]		61
Operating Leases, Future Minimum Payments, Due Thereafter	[1]		159
Operating Leases, Future Minimum Payments Due	[1]		692
Capital Leases, Future Minimum Payments, Net Present Value [Abstract]
Capital Leases, Future Minimum Payments Due, Next Twelve Months	[1]		69
Capital Leases, Future Minimum Payments Due in Two Years	[1]		68
Capital Leases, Future Minimum Payments Due in Three Years	[1]		73
Capital Leases, Future Minimum Payments Due in Four Years	[1]		67
Capital Leases, Future Minimum Payments Due in Five Years	[1]		56
Capital Leases, Future Minimum Payments Due Thereafter	[1]		772
Capital Leases, Future Minimum Payments Due	[1]		1,105
Lease, Liability, Payments, Remainder of Fiscal Year		54	216	[1]
Lease, Liability, Payments, Due Year Two		209	196	[1]
Lease, Liability, Payments, Due Year Three		194	183	[1]
Lease, Liability, Payments, Due Year Four		165	154	[1]
Lease, Liability, Payments, Due Year Five		126	117	[1]
Lease, Liability, Payments, Due after Year Five		1,020	931	[1]
Lease, Liability, Payments, Due		1,768	1,797	[1]
Lease, Liability, Undiscounted Excess Amount		(677)
Total Lease Liabilities		1,091
Nevada Power Company [Member]
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year		1
Lessee, Operating Lease, Liability, Payments, Due Year Two		3
Lessee, Operating Lease, Liability, Payments, Due Year Three		3
Lessee, Operating Lease, Liability, Payments, Due Year Four		2
Lessee, Operating Lease, Liability, Payments, Due Year Five		2
Lessee, Operating Lease, Liability, Payments, Due after Year Five		9
Lessee, Operating Lease, Liability, Payments, Due		20
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(3)
Operating Lease, Liability		17
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, Payments, Remainder of Fiscal Year		13
Finance Lease, Liability, Payments, Due Year Two		59
Finance Lease, Liability, Payments, Due Year Three		63
Finance Lease, Liability, Payments, Due Year Four		61
Finance Lease, Liability, Payments, Due Year Five		51
Finance Lease, Liability, Payments, Due after Year Five		715
Finance Lease, Liability, Payment, Due		962
Finance Lease, Liability, Undiscounted Excess Amount		(508)
Finance Lease, Liability		454
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	[2]		3
Operating Leases, Future Minimum Payments, Due in Two Years	[2]		3
Operating Leases, Future Minimum Payments, Due in Three Years	[2]		3
Operating Leases, Future Minimum Payments, Due in Four Years	[2]		3
Operating Leases, Future Minimum Payments, Due in Five Years	[2]		2
Operating Leases, Future Minimum Payments, Due Thereafter	[2]		10
Operating Leases, Future Minimum Payments Due	[2]		24
Capital Leases, Future Minimum Payments, Net Present Value [Abstract]
Capital Leases, Future Minimum Payments Due, Next Twelve Months	[2]		59
Capital Leases, Future Minimum Payments Due in Two Years	[2]		59
Capital Leases, Future Minimum Payments Due in Three Years	[2]		61
Capital Leases, Future Minimum Payments Due in Four Years	[2]		60
Capital Leases, Future Minimum Payments Due in Five Years	[2]		50
Capital Leases, Future Minimum Payments Due Thereafter	[2]		709
Capital Leases, Future Minimum Payments Due	[2]		998
Lease, Liability, Payments, Remainder of Fiscal Year		14	62	[2]
Lease, Liability, Payments, Due Year Two		62	62	[2]
Lease, Liability, Payments, Due Year Three		66	64	[2]
Lease, Liability, Payments, Due Year Four		63	63	[2]
Lease, Liability, Payments, Due Year Five		53	52	[2]
Lease, Liability, Payments, Due after Year Five		724	719	[2]
Lease, Liability, Payments, Due		982	$ 1,022	[2]
Lease, Liability, Undiscounted Excess Amount		(511)
Total Lease Liabilities		$ 471

[1] (1) Amounts included for comparability and accounted for in accordance with ASC 840, "Leases".

[2] Amounts included for comparability and accounted for in accordance with ASC Topic 840, "Leases".