Property, Plant and Equipment, Net - NPC (Details) - Nevada Power Company [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Plant, net	$ 6,559	$ 6,343
Construction work- in-progress	142	195
Property, plant and equipment, net	$ 6,701	$ 6,538
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.10%	3.30%	3.20%
Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	$ 3,690	$ 3,541
Public Utilities, Property, Plant and Equipment, Distribution	3,771	3,567
Public Utilities, Property, Plant and Equipment, Transmission	1,468	1,444
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	791	741
Plant in service, net	9,720	9,293
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	3,162	2,951
Plant, net	6,558	6,342
Nonregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Plant, net	$ 1	$ 1
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	45 years
Minimum [Member] | Regulated Operation [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
Maximum [Member] | Regulated Operation [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