Subsidiary Debt Subsidiary Debt - SPPC - Long-Term Debt (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Par value		$ 39,634
Long-term Debt		39,353	$ 36,774
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value		30,883
Other long-term debt		30,672	27,573
Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt		1,135	1,120
Long-term Debt, Excluding Current Maturities		1,135	1,120
NV Energy [Member]
Debt Instrument [Line Items]
Par value		3,836
Other long-term debt		3,821	3,817
NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value		3,836
Other long-term debt		3,821	3,817
NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value		1,137
Other long-term debt		1,136	1,121
NV Energy [Member] | Sierra Pacific Power Company [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member]
Debt Instrument [Line Items]
Par value		250
Other long-term debt		249	249
NV Energy [Member] | Sierra Pacific Power Company [Member] | Mortgage securities, 2.600%, Series U due 2026 [Member]
Debt Instrument [Line Items]
Par value		400
Other long-term debt		396	396
NV Energy [Member] | Sierra Pacific Power Company [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member]
Debt Instrument [Line Items]
Par value		252
Other long-term debt		256	256
NV Energy [Member] | Sierra Pacific Power Company [Member] | Pollution Control Refunding Revenue Bonds, 1.250%, Series 2016A, due 2029 [Member]
Debt Instrument [Line Items]
Par value		0
Other long-term debt			20
NV Energy [Member] | Sierra Pacific Power Company [Member] | Pollution Control Refunding Revenue Bonds, 1.850%, Series 2016B, due 2029 [Member]
Debt Instrument [Line Items]
Par value	[1]	30
NV Energy [Member] | Sierra Pacific Power Company [Member] | Gas facilities refunding revenue bonds, 1.500%, series 2016A, due 2031 [Member]
Debt Instrument [Line Items]
Par value		0
Other long-term debt			58
NV Energy [Member] | Sierra Pacific Power Company [Member] | Gas and water facilities refunding revenue bonds, 3.000% series 2016B, due 2036 [Member]
Debt Instrument [Line Items]
Par value	[2]	60
Other long-term debt			62
NV Energy [Member] | Sierra Pacific Power Company [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member]
Debt Instrument [Line Items]
Par value	[3]	0
Other long-term debt			30
NV Energy [Member] | Sierra Pacific Power Company [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member]
Debt Instrument [Line Items]
Par value	[1],[4]	25
Other long-term debt			25
NV Energy [Member] | Sierra Pacific Power Company [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member]
Debt Instrument [Line Items]
Par value	[1],[4]	25
Other long-term debt			$ 25
NV Energy [Member] | Sierra Pacific Power Company [Member] | Water facilities refunding revenue bonds, series 2016F, due 2036 [Member]
Debt Instrument [Line Items]
Par value	[1]	75
NV Energy [Member] | Sierra Pacific Power Company [Member] | Water facilities refunding revenue bonds, series 2016G, due 2036 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 20
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.375%	3.375%
Long-term Debt		$ 249	$ 249
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Mortgage securities, 2.600%, Series U due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.60%	2.60%
Long-term Debt		$ 396	$ 396
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.75%	6.75%
Long-term Debt		$ 255	$ 255
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Pollution Control Refunding Revenue Bonds, 1.250%, Series 2016A, due 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.25%	1.25%
Long-term Debt		$ 0	$ 20
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Pollution Control Refunding Revenue Bonds, 1.850%, Series 2016B, due 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.85%	0.00%
Long-term Debt	[1]	$ 29	$ 0
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Gas facilities refunding revenue bonds, 1.500%, series 2016A, due 2031 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.50%	1.50%
Long-term Debt		$ 0	$ 58
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Gas and water facilities refunding revenue bonds, 3.000% series 2016B, due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.00%	3.00%
Long-term Debt	[2]	$ 62	$ 62
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.85%
Long-term Debt	[3]	$ 0	30
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.05%
Long-term Debt	[1],[4]	$ 25	25
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.05%
Long-term Debt	[1],[4]	$ 25	$ 25
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016F, due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.05%	0.00%
Long-term Debt	[1]	$ 74	$ 0
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Water facilities refunding revenue bonds, series 2016G, due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.85%	0.00%
Long-term Debt	[1]	$ 20	$ 0
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Minimum [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate			1.75%
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Minimum [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate			1.75%
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Minimum [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate			1.75%
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Maximum [Member] | Water facilities refunding revenue bonds, series 2016C, due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate			1.82%
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Maximum [Member] | Water facilities refunding revenue bonds, series 2016D, due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate			1.82%
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member] | Maximum [Member] | Water facilities refunding revenue bonds, series 2016E, due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate			1.82%

[1] Subject to mandatory purchase by Sierra Pacific in April 2022 at which date the interest rate may be adjusted from time to time.

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

[3] (3)Bond was purchased by Sierra Pacific during 2019. As of December 31, 2018 the bond variable interest rate was 1.750% to 1.820%.

[4] (4)Bonds were purchased by Sierra Pacific during 2019 and re-offered at a fixed interest rate. As of December 31, 2018 the bonds variable interest rate was 1.750% to 1.820%.