Subsidiary Debt Subsidiary Debt - SPPC - Capital and Financial Lease Obligations (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2014	Dec. 31, 2014	Dec. 31, 2015
Debt Instrument [Line Items]
Par value			$ 38,133
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value			27,314
Other long-term debt		$ 26,848	27,214
Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			1,203
Total Long-term Debt and Capital and Financial Lease Obligations		1,190	1,202
Long-term Debt and Capital and Financial Lease Obligations, Current		1	453
Long-term Debt and Capital and Financial Lease Obligations		1,189	749
Long-term Debt and Capital and Financial Lease Obligations, Including Current Maturities		1,190	1,202
Debt Required To Be Tendered		$ 702
Debt Instrument, Redemption Price, Percentage		101.00%
Extinguishment of Debt, Amount	$ 0
NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value			4,840
Other long-term debt		$ 5,118	4,860
NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value			1,203
Other long-term debt		$ 1,190	$ 1,202
Mortgage securities, 6.000%, Series M due 2016 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.00%	6.00%
Mortgage securities, 6.000%, Series M due 2016 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			$ 450
Mortgage securities, 6.000%, Series M due 2016 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		$ 451	$ 450
Debt Instrument, Interest Rate, Stated Percentage		6.00%	6.00%
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, 3.375%, Series T due 2023 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			$ 250
Mortgage securities, 3.375%, Series T due 2023 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		$ 247	$ 248
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%
Mortgage securities, 6.750%, Series P due 2037 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			$ 252
Mortgage securities, 6.750%, Series P due 2037 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		$ 255	$ 255
Debt Instrument, Interest Rate, Stated Percentage		6.75%	6.75%
Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			$ 58
Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		$ 58	58
Pollution Control Revenue Bonds, Variable-Rate, Series 2006B due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			75
Pollution Control Revenue Bonds, Variable-Rate, Series 2006B due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		74	74
Pollution Control Revenue Bonds, Variable-Rate, Series 2006C due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			81
Pollution Control Revenue Bonds, Variable-Rate, Series 2006C due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		79	80
Capital and financial lease obligations, 2.700% to 8.548%, due through 2054 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value			37
Capital and financial lease obligations, 2.700% to 8.548%, due through 2054 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Other long-term debt		$ 26	$ 37
Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		0.464%	0.733%
Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		0.464%	0.733%
Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006B due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		0.464%	0.733%
Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006B due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		0.464%	0.733%
Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006C due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		0.464%	0.733%
Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006C due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		0.464%	0.733%
Minimum [Member] | Capital and financial lease obligations, 2.700% to 8.548%, due through 2054 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		2.70%	2.70%
Minimum [Member] | Capital and financial lease obligations, 2.700% to 8.548%, due through 2054 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		2.70%	2.70%
Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		0.466%	1.054%
Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2031 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		0.466%	1.054%
Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006B due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		0.466%	1.054%
Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006B due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		0.466%	1.054%
Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006C due 2036 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		0.466%	1.054%
Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006C due 2036 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		0.466%	1.054%
Maximum [Member] | Capital and financial lease obligations, 2.700% to 8.548%, due through 2054 [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Variable interest rate		8.814%	8.548%
Maximum [Member] | Capital and financial lease obligations, 2.700% to 8.548%, due through 2054 [Member] | NV Energy [Member] | Sierra Pacific Power Company [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Variable interest rate		8.548%	8.548%
Equipment [Member] | Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Capital Leased Assets, Gross		$ 3	$ 3