Property, Plant and Equipment, Net - SPPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 2,715	$ 2,678
Public Utilities, Property, Plant and Equipment, Net	$ 2,822	$ 2,766
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.00%	2.90%	3.00%
Nevada Power Company [Member]
Public Utility, 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%
Electricity Generation Plant, Non-Nuclear [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	$ 1,137	$ 1,134
Public Utilities, Property, Plant and Equipment, Distribution	1,417	1,382
Public Utilities, Property, Plant and Equipment, Transmission	771	739
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	$ 164	$ 139
Electricity Generation Plant, Non-Nuclear [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Public Utility, 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, Other Property Plant and Equipment, Useful Life	5 years	5 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	50 years	50 years
Electricity Generation Plant, Non-Nuclear [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	60 years	60 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	70 years	70 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	65 years	65 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	70 years	70 years
Natural Gas Processing Plant [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution	$ 381	$ 374
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	$ 15	$ 13
Natural Gas Processing Plant [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	40 years	40 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	5 years	5 years
Natural Gas Processing Plant [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	70 years	70 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	60 years	60 years
Common Facilities [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common	$ 267	$ 265
Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress	4,152	4,046
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(1,442)	(1,368)
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	2,710	2,678
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	107	88
Public Utilities, Property, Plant and Equipment, Net	$ 2,822	$ 2,766
Common Facilities [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common, Useful Life	5 years	5 years
Common Facilities [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common, Useful Life	65 years	65 years
Nonregulated Operation [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 5	$ 0
Nonregulated Operation [Member] | Nevada Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 2	$ 2
Nonregulated Operation [Member] | Minimum [Member] | Nevada Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	45 years	45 years
Nonregulated Operation [Member] | Maximum [Member] | Nevada Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	45 years	45 years
Electricity Generation Plant, Non-Nuclear [Member] | Sierra Pacific Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Change in Accounting Estimates, Impact on Future Periods		$ 9
Change in Accounting Estimate, Amount Deferred to Future Periods	$ 7