Property, Plant and Equipment, Net Property, Plant and Equipment, Net - NPC (Details) - Nevada Power Company [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 6,478	$ 6,343
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	165	195
Property, plant and equipment, net	6,643	6,538
Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	3,612	3,541
Public Utilities, Property, Plant and Equipment, Transmission	1,455	1,444
Public Utilities, Property, Plant and Equipment, Distribution	3,738	3,567
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	784	741
Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress	9,589	9,293
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	3,112	2,951
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 6,477	6,342
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, Transmission, Useful Life	45 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	20 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, Transmission, Useful Life	70 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	65 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