Property, Plant and Equipment, Net Property, Plant and Equipment, Net - NPC (Details) - Nevada Power Company [Member] - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 6,325	$ 6,321
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	132	97
Property, plant and equipment, net	6,457	6,418
Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	3,724	3,720
Public Utilities, Property, Plant and Equipment, Distribution	3,472	3,411
Public Utilities, Property, Plant and Equipment, Transmission	1,446	1,439
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	709	716
Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress	9,351	9,286
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	3,027	2,966
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 6,324	6,320
Regulated Operation [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	30 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	20 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	45 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	5 years
Regulated Operation [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	55 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	65 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	70 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	65 years
Unregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 1	$ 1
Unregulated Operation [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	45 years
Unregulated Operation [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	45 years