Subsidiary Debt Subsidiary Debt - SPPC (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017
Debt Instrument [Line Items]
Par value		$ 37,014
Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value		1,159
Eligible Property Subject To Lien Of Mortgages		4,100
Sierra Pacific Power Company [Member] | Equipment [Member]
Debt Instrument [Line Items]
Capital Leased Assets, Gross		$ 8		$ 3
Sierra Pacific Power Company [Member] | ON Line Transmission Line [Member]
Debt Instrument [Line Items]
Terms Of Capital Lease		41 years
Capital Leased Assets, Gross		$ 20		21
Utilities Aggregate Share Transmission Line Project		25.00%
Remaining Share Transmission Line Project		75.00%
Sierra Pacific Power Company [Member] | Solar Generating Facility [Member]
Debt Instrument [Line Items]
Terms Of Capital Lease		20 years
Capital Leased Assets, Gross		$ 9		$ 9
Sierra Pacific Power Company [Member] | Sierra Pacific Power Company [Member] | ON Line Transmission Line [Member]
Debt Instrument [Line Items]
Utilities Aggregate Share Transmission Line Project		5.00%
Sierra Pacific Power Company [Member] | Nevada Power Company [Member] | ON Line Transmission Line [Member]
Debt Instrument [Line Items]
Utilities Aggregate Share Transmission Line Project		95.00%
Minimum [Member] | Sierra Pacific Power Company [Member] | Equipment [Member]
Debt Instrument [Line Items]
Terms Of Capital Lease		5 years
Maximum [Member] | Sierra Pacific Power Company [Member] | Equipment [Member]
Debt Instrument [Line Items]
Terms Of Capital Lease		7 years
Mortgage securities, 3.375%, Series T due 2023 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.375%		3.375%
Mortgage securities, 6.750%, Series P due 2037 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.75%		6.75%
Capital and financial lease obligations, 2.700% to 10.297%, due through 2054 [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		2.70%		2.70%
Capital and financial lease obligations, 2.700% to 10.297%, due through 2054 [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		10.297%		10.396%
NV Energy [Member]
Debt Instrument [Line Items]
Other long-term debt		$ 4,318		$ 4,581
Par value		4,321
NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		1,159		1,156
Par value		1,159
NV Energy [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		249		249
Par value		250
NV Energy [Member] | Mortgage securities, 2.600%, Series U due 2026 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		396		396
Par value		400
NV Energy [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		256		256
Par value		252
NV Energy [Member] | Pollution Control Refunding Revenue Bonds, 1.250%, Series 2016A, due 2029 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		20	[1]	20
Par value	[1]	20
NV Energy [Member] | Gas facilities refunding revenue bonds, 1.500%, series 2016A, due 2031 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		58	[1]	58
Par value	[1]	59
NV Energy [Member] | Gas and water facilities refunding revenue bonds, 3.000% series 2016B, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		62	[2]	63
Par value	[2]	60
NV Energy [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		30		30
Par value		30
NV Energy [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		25		25
Par value		25
NV Energy [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		25		25
Par value		25
NV Energy [Member] | Capital lease obligations, 2.700% to 10.297%, due through 2054 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		38		34
Par value		38
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		28,097		28,641
Par value		28,263
Subsidiary Debt [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		249		248
Subsidiary Debt [Member] | Mortgage securities, 2.600%, Series U due 2026 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		396		396
Subsidiary Debt [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt		255		255
Subsidiary Debt [Member] | Pollution Control Refunding Revenue Bonds, 1.250%, Series 2016A, due 2029 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt	[1]			20
Subsidiary Debt [Member] | Gas facilities refunding revenue bonds, 1.500%, series 2016A, due 2031 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt	[1]			58
Subsidiary Debt [Member] | Gas and water facilities refunding revenue bonds, 3.000% series 2016B, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt	[2]			63
Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt				30
Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt				25
Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt				25
Subsidiary Debt [Member] | Capital lease obligations, 2.700% to 10.297%, due through 2054 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Other long-term debt				34
Subsidiary Debt [Member] | NV Energy [Member]
Debt Instrument [Line Items]
Other long-term debt		4,318		$ 4,581
Par value		$ 4,321
Subsidiary Debt [Member] | NV Energy [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.375%		3.375%
Subsidiary Debt [Member] | NV Energy [Member] | Mortgage securities, 2.600%, Series U due 2026 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.60%		2.60%
Subsidiary Debt [Member] | NV Energy [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.75%		6.75%
Subsidiary Debt [Member] | NV Energy [Member] | Pollution Control Refunding Revenue Bonds, 1.250%, Series 2016A, due 2029 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.25%		1.25%
Subsidiary Debt [Member] | NV Energy [Member] | Gas facilities refunding revenue bonds, 1.500%, series 2016A, due 2031 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.50%		1.50%
Subsidiary Debt [Member] | NV Energy [Member] | Gas and water facilities refunding revenue bonds, 3.000% series 2016B, due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.00%		3.00%
Subsidiary Debt [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.75%		1.69%
Subsidiary Debt [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.82%		1.84%
Subsidiary Debt [Member] | NV Energy [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.75%		1.69%
Subsidiary Debt [Member] | NV Energy [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.82%		1.84%
Subsidiary Debt [Member] | NV Energy [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.75%		1.69%
Subsidiary Debt [Member] | NV Energy [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.82%		1.84%
Subsidiary Debt [Member] | NV Energy [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.75%		1.69%
Subsidiary Debt [Member] | NV Energy [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		1.82%		1.84%
Subsidiary Debt [Member] | NV Energy [Member] | Capital and financial lease obligations, 2.700% to 10.297%, due through 2054 [Member] | Minimum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		2.70%		2.70%
Subsidiary Debt [Member] | NV Energy [Member] | Capital and financial lease obligations, 2.700% to 10.297%, due through 2054 [Member] | Maximum [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		10.297%		10.369%

[1] (2) Subject to mandatory purchase by Sierra Pacific in June 2019 at which date the interest rate may be adjusted from time to time.

[2] (3) Subject to mandatory purchase by Sierra Pacific in June 2022 at which date the interest rate may be adjusted from time to time.