Property, Plant and Equipment, Net Property, Plant and Equipment, Net - SPPC (Details) - Sierra Pacific Power Company [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 3,026	$ 3,027
Property, plant and equipment, net	3,188	3,164
Common Facilities [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	162	137
Property, plant and equipment, net	3,188	3,164
Regulated Operation [Member] | Electricity Generation Plant, Non-Nuclear [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	1,131	1,130
Public Utilities, Property, Plant and Equipment, Transmission	917	908
Public Utilities, Property, Plant and Equipment, Distribution	1,763	1,754
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	$ 193	189
Regulated Operation [Member] | Electricity Generation Plant, Non-Nuclear [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	25 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	50 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] | Electricity Generation Plant, Non-Nuclear [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	60 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	100 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	100 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	70 years
Regulated Operation [Member] | Natural Gas Processing Plant [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution	$ 431	429
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	$ 15	15
Regulated Operation [Member] | Natural Gas Processing Plant [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	35 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	5 years
Regulated Operation [Member] | Natural Gas Processing Plant [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	70 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	70 years
Regulated Operation [Member] | Common Facilities [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common	$ 357	355
Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress	4,807	4,780
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	1,783	1,755
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 3,024	3,025
Regulated Operation [Member] | Common Facilities [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common, Useful Life	5 years
Regulated Operation [Member] | Common Facilities [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common, Useful Life	70 years
Unregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 2	$ 2
Unregulated Operation [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	70 years