Property, Plant and Equipment, Net - NPC (Details) - Nevada Power Company [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 6,343	$ 6,321
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	195	97
Public Utilities, Property, Plant and Equipment, Net	$ 6,538	$ 6,418
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.30%	3.20%	3.20%
Electricity Generation Plant, Non-Nuclear [Member]
Property, Plant and Equipment [Line Items]
Change in Accounting Estimates, Impact on Period of Change	$ 7
Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	3,541	$ 3,720
Public Utilities, Property, Plant and Equipment, Distribution	3,567	3,411
Public Utilities, Property, Plant and Equipment, Transmission	1,444	1,439
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	741	716
Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress	9,293	9,286
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	2,951	2,966
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	6,342	6,320
Nonregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 1	$ 1
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	70 years	70 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