Property, Plant and Equipment, Net - NPC (Details) - Nevada Power Company [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 6,883	$ 6,843
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	114	153
Public Utilities, Property, Plant and Equipment, Net	$ 6,997	$ 6,996
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.20%	3.00%	3.30%
Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	$ 4,271	$ 4,212
Public Utilities, Property, Plant and Equipment, Distribution	3,231	3,118
Public Utilities, Property, Plant and Equipment, Transmission	1,846	1,788
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	738	694
Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress	10,086	9,812
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	3,205	2,971
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	6,881	6,841
Nonregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 2	$ 2
Minimum [Member] | Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	30 years	30 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	20 years	20 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	45 years	45 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	5 years	5 years
Minimum [Member] | Nonregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	45 years	45 years
Maximum [Member] | Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	55 years	55 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	65 years	65 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	65 years	65 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	65 years	65 years
Maximum [Member] | Nonregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	45 years	45 years