Subsidiary Debt - NV Energy (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Par value	$ 38,133
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	27,314
Other long-term debt	27,214	$ 26,848
NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	4,840
Other long-term debt	4,860	5,118
NV Energy, Inc. [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Senior Notes, 6.250%, due 2020 [Member]
Debt Instrument [Line Items]
Par value	315
Other long-term debt	$ 373	$ 384
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%
Nevada Power Company [Member]
Debt Instrument [Line Items]
Par value	$ 3,322
Eligible Property Subject To Lien Of Mortgages	$ 8,700
Nevada Power Company [Member] | Mortgage Securities, 5.875%, Series L due 2015 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.875%	5.875%
Nevada Power Company [Member] | Mortgage Securities, 5.950%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.95%	5.95%
Nevada Power Company [Member] | Mortgage Securities, 6.500%, Series O due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%	6.50%
Nevada Power Company [Member] | Mortgage Securities, 6.500%, Series S due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%	6.50%
Nevada Power Company [Member] | Mortgage Securities, 7.125%, Series V due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.125%	7.125%
Nevada Power Company [Member] | Mortgage Securities, 6.650%, Series N due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.65%	6.65%
Nevada Power Company [Member] | Mortgage Securities, 6.750%, Series R due 2037 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.75%	6.75%
Nevada Power Company [Member] | Mortgage Securities, 5.375%, Series X due 2040 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.375%	5.375%
Nevada Power Company [Member] | Mortgage Securities, 5.450%, Series Y due 2041 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.45%	5.45%
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 5.875%, Series L due 2015 [Member]
Debt Instrument [Line Items]
Par value	$ 0
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 5.950%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Par value	210
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 6.500%, Series O due 2018 [Member]
Debt Instrument [Line Items]
Par value	324
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 6.500%, Series S due 2018 [Member]
Debt Instrument [Line Items]
Par value	499
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 7.125%, Series V due 2019 [Member]
Debt Instrument [Line Items]
Par value	500
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 6.650%, Series N due 2036 [Member]
Debt Instrument [Line Items]
Par value	367
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 6.750%, Series R due 2037 [Member]
Debt Instrument [Line Items]
Par value	349
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 5.375%, Series X due 2040 [Member]
Debt Instrument [Line Items]
Par value	250
Nevada Power Company [Member] | NV Energy [Member] | Mortgage Securities, 5.450%, Series Y due 2041 [Member]
Debt Instrument [Line Items]
Par value	250
Nevada Power Company [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Par value	38
Nevada Power Company [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006 due 2036 [Member]
Debt Instrument [Line Items]
Par value	38
Nevada Power Company [Member] | NV Energy [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Par value	497
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	3,322
Other long-term debt	3,285	$ 3,544
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.875%, Series L due 2015 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 0	$ 250
Debt Instrument, Interest Rate, Stated Percentage	0.00%	5.875%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.950%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 210	$ 209
Debt Instrument, Interest Rate, Stated Percentage	5.95%	5.95%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series O due 2018 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 323	$ 322
Debt Instrument, Interest Rate, Stated Percentage	6.50%	6.50%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series S due 2018 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 498	$ 497
Debt Instrument, Interest Rate, Stated Percentage	6.50%	6.50%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 7.125%, Series V due 2019 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 499	$ 499
Debt Instrument, Interest Rate, Stated Percentage	7.125%	7.125%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.650%, Series N due 2036 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 356	$ 356
Debt Instrument, Interest Rate, Stated Percentage	6.65%	6.65%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.750%, Series R due 2037 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 345	$ 345
Debt Instrument, Interest Rate, Stated Percentage	6.75%	6.75%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.375%, Series X due 2040 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 247	$ 247
Debt Instrument, Interest Rate, Stated Percentage	5.375%	5.375%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.450%, Series Y due 2041 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 235	$ 234
Debt Instrument, Interest Rate, Stated Percentage	5.45%	5.45%
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 38	$ 38
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006 due 2036 [Member]
Debt Instrument [Line Items]
Other long-term debt	37	37
Nevada Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 497	$ 510
Nevada Power Company [Member] | Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.672%	0.454%
Nevada Power Company [Member] | Minimum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006 due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.672%	0.454%
Nevada Power Company [Member] | Minimum [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	2.75%	2.75%
Nevada Power Company [Member] | Minimum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.672%	0.455%
Nevada Power Company [Member] | Minimum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006 due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.672%	0.455%
Nevada Power Company [Member] | Minimum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	2.75%	2.75%
Nevada Power Company [Member] | Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.055%	0.459%
Nevada Power Company [Member] | Maximum [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006 due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.055%	0.459%
Nevada Power Company [Member] | Maximum [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	11.60%	11.60%
Nevada Power Company [Member] | Maximum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.055%	0.464%
Nevada Power Company [Member] | Maximum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, Variable-Rate, Series 2006 due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.055%	0.464%
Nevada Power Company [Member] | Maximum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	11.60%	11.60%
Sierra Pacific Power Company [Member]
Debt Instrument [Line Items]
Par value	$ 1,203
Eligible Property Subject To Lien Of Mortgages	$ 3,700
Sierra Pacific Power Company [Member] | Mortgage securities, 6.000%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%	6.00%
Sierra Pacific Power Company [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.375%	3.375%
Sierra Pacific Power Company [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.75%	6.75%
Sierra Pacific Power Company [Member] | NV Energy [Member] | Mortgage securities, 6.000%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Par value	$ 450
Sierra Pacific Power Company [Member] | NV Energy [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member]
Debt Instrument [Line Items]
Par value	250
Sierra Pacific Power Company [Member] | NV Energy [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member]
Debt Instrument [Line Items]
Par value	252
Sierra Pacific Power Company [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Par value	58
Sierra Pacific Power Company [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Par value	75
Sierra Pacific Power Company [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Par value	81
Sierra Pacific Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	1,203
Other long-term debt	1,202	$ 1,190
Sierra Pacific Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage securities, 6.000%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 450	$ 451
Debt Instrument, Interest Rate, Stated Percentage	6.00%	6.00%
Sierra Pacific Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 248	$ 247
Debt Instrument, Interest Rate, Stated Percentage	3.375%	3.375%
Sierra Pacific Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 255	$ 255
Debt Instrument, Interest Rate, Stated Percentage	6.75%	6.75%
Sierra Pacific Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 58	$ 58
Sierra Pacific Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Other long-term debt	74	74
Sierra Pacific Power Company [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 80	$ 79
Sierra Pacific Power Company [Member] | Minimum [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.733%	0.464%
Sierra Pacific Power Company [Member] | Minimum [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.733%	0.464%
Sierra Pacific Power Company [Member] | Minimum [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.733%	0.464%
Sierra Pacific Power Company [Member] | Minimum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.733%	0.464%
Sierra Pacific Power Company [Member] | Minimum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.733%	0.464%
Sierra Pacific Power Company [Member] | Minimum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.733%	0.464%
Sierra Pacific Power Company [Member] | Maximum [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.054%	0.466%
Sierra Pacific Power Company [Member] | Maximum [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.054%	0.466%
Sierra Pacific Power Company [Member] | Maximum [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.054%	0.466%
Sierra Pacific Power Company [Member] | Maximum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.054%	0.466%
Sierra Pacific Power Company [Member] | Maximum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.054%	0.466%
Sierra Pacific Power Company [Member] | Maximum [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.464% to 0.466%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.054%	0.466%