Subsidiary Debt - NV Energy (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Debt Instrument [Line Items]
Par value	$ 31,956
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	22,737
Other long-term debt	22,802		16,114
NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	5,242
Other long-term debt	5,296		0
NV Energy [Member] | NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	510
Other long-term debt	564		0
NV Energy [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Variable rate term loan due 2014 [Member]
Debt Instrument [Line Items]
Par value	195	[1]
Other long-term debt	195	[1]	0	[1]
Variable interest rate	1.92%
Interest rate swaps average fixed rate	2.56%
Stated interest rate			0.00%
NV Energy [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	369		0
Stated interest rate	6.25%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	3,542
Other long-term debt	3,532		0
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.875%, Series L due 2015 [Member]
Debt Instrument [Line Items]
Par value	250
Other long-term debt	250		0
Stated interest rate	5.875%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.950%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Par value	210
Other long-term debt	210		0
Stated interest rate	5.95%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series O due 2018 [Member]
Debt Instrument [Line Items]
Par value	325
Other long-term debt	324		0
Stated interest rate	6.50%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series S due 2018 [Member]
Debt Instrument [Line Items]
Par value	500
Other long-term debt	499		0
Stated interest rate	6.50%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 7.125%, Series V due 2019 [Member]
Debt Instrument [Line Items]
Par value	500
Other long-term debt	501		0
Stated interest rate	7.125%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.650%, Series N due 2036 [Member]
Debt Instrument [Line Items]
Par value	370
Other long-term debt	363		0
Stated interest rate	6.65%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.750%, Series R due 2037 [Member]
Debt Instrument [Line Items]
Par value	350
Other long-term debt	349		0
Stated interest rate	6.75%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.375%, Series X due 2040 [Member]
Debt Instrument [Line Items]
Par value	250
Other long-term debt	249		0
Stated interest rate	5.375%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.450%, Series Y due 2041 [Member]
Debt Instrument [Line Items]
Par value	250
Other long-term debt	250		0
Stated interest rate	5.45%		0.00%
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.454% to 0.459%, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Par value	38
Other long-term debt	38		0
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.454% to 0.459%, Series 2006A due 2036 [Member]
Debt Instrument [Line Items]
Par value	38
Other long-term debt	38		0
Nevada Power [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Capital lease obligations, 3.01% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Par value	461
Other long-term debt	461		0
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	1,190
Other long-term debt	1,200		0
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage securities, 6.000%, Series M due 2016 [Member]
Debt Instrument [Line Items]
Par value	450
Other long-term debt	453		0
Stated interest rate	6.00%		0.00%
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage securities, 3.375%, Series T due 2023 [Member]
Debt Instrument [Line Items]
Par value	250
Other long-term debt	250		0
Stated interest rate	3.375%		0.00%
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Mortgage securities, 6.750%, Series P due 2037 [Member]
Debt Instrument [Line Items]
Par value	252
Other long-term debt	259		0
Stated interest rate	6.75%		0.00%
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Par value	58
Other long-term debt	58		0
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Par value	75
Other long-term debt	75		0
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Par value	81
Other long-term debt	81		0
Sierra Pacific [Member] | NV Energy [Member] | Subsidiary Debt [Member] | Capital lease obligations, 3.01% to 8.52%, due through 2054 [Member]
Debt Instrument [Line Items]
Par value	24
Other long-term debt	$ 24		$ 0
Minimum [Member] | Nevada Power [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.454% to 0.459%, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.454%		0.00%
Minimum [Member] | Nevada Power [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.454% to 0.459%, Series 2006A due 2036 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.454%		0.00%
Minimum [Member] | Nevada Power [Member] | NV Energy [Member] | Capital lease obligations, 3.01% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Variable interest rate	3.01%		0.00%
Minimum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.459%		0.00%
Minimum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.459%		0.00%
Minimum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.459%		0.00%
Minimum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Capital lease obligations, 3.01% to 8.52%, due through 2054 [Member]
Debt Instrument [Line Items]
Variable interest rate	3.01%		0.00%
Maximum [Member] | Nevada Power [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.454% to 0.459%, Series 2006A due 2032 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.459%		0.00%
Maximum [Member] | Nevada Power [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.454% to 0.459%, Series 2006A due 2036 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.459%		0.00%
Maximum [Member] | Nevada Power [Member] | NV Energy [Member] | Capital lease obligations, 3.01% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Variable interest rate	11.60%		0.00%
Maximum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006A due 2031 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.463%		0.00%
Maximum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006B due 2036 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.463%		0.00%
Maximum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Pollution Control Revenue Bonds, 0.459% to 0.463%, Series 2006C due 2036 [Member]
Debt Instrument [Line Items]
Variable interest rate	0.463%		0.00%
Maximum [Member] | Sierra Pacific [Member] | NV Energy [Member] | Capital lease obligations, 3.01% to 8.52%, due through 2054 [Member]
Debt Instrument [Line Items]
Variable interest rate	8.52%		0.00%

[1] The term loan has a variable interest rate based on LIBOR plus a spread that varies during the term of the agreement. The variable interest rate as of December 31, 2013 was 1.92%. The Company has entered into an interest rate swap that fixes the interest rate at 2.56% as of December 31, 2013.