LONG-TERM DEBT, Debt Instruments (Details) (USD $) In Thousands, unless otherwise specified			12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended													12 Months Ended																						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, NPC Series I [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, NPC Series I [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, NPC Series L [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, NPC Series L [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, NPC Series M [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, NPC Series M [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, NPC Series N [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, NPC Series N [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, NPC Series O [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, NPC Series O [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, NPC Series R [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, NPC Series R [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, NPC Series S [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, NPC Series S [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, Series U [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, Series U [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, Series V [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, Series V [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, Series X [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, Series X [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, Series Y [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, Series Y [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, SPPC Series M [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, SPPC Series M [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, SPPC Series P [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, SPPC Series P [Member]	Dec. 31, 2012 Secured, General and Refunding Mortgage Securities, SPPC Series Q [Member]	Dec. 31, 2011 Secured, General and Refunding Mortgage Securities, SPPC Series Q [Member]	Dec. 31, 2012 Secured Variable Rate Debt NPC IDRB Series 2000A [Member]	Dec. 31, 2011 Secured Variable Rate Debt NPC IDRB Series 2000A [Member]	Dec. 31, 2012 Secured Variable Rate Debt, NPC PCRB Series 2006 [Member]	Dec. 31, 2011 Secured Variable Rate Debt, NPC PCRB Series 2006 [Member]	Dec. 31, 2012 Secured Variable Rate Debt Npc Pcrb Series 2006A [Member]	Dec. 31, 2011 Secured Variable Rate Debt Npc Pcrb Series 2006A [Member]	Dec. 31, 2012 Secured Variable Rate Debt Sppc Pcrb Series 2006 [Member]	Dec. 31, 2011 Secured Variable Rate Debt Sppc Pcrb Series 2006 [Member]	Dec. 31, 2012 Secured Variable Rate Debt Sppc Pcrb Series 2006 B [Member]	Dec. 31, 2011 Secured Variable Rate Debt Sppc Pcrb Series 2006 B [Member]	Dec. 31, 2012 Secured Variable Rate Debt Sppc Pcrb Series 2006 C [Member]	Dec. 31, 2011 Secured Variable Rate Debt Sppc Pcrb Series 2006 C [Member]	Dec. 31, 2012 NVE Senior Notes due 2014 [Member]	Dec. 31, 2011 NVE Senior Notes due 2014 [Member]	Dec. 31, 2012 NVE Senior Notes due 2020 [Member]	Dec. 31, 2011 NVE Senior Notes due 2020 [Member]	Dec. 31, 2012 Capital Lease Obligations [Member]	Dec. 31, 2011 Capital Lease Obligations [Member]	Dec. 31, 2012 NVE [Member]	Dec. 31, 2011 NVE [Member]	Dec. 31, 2012 NVE [Member] NVE Senior Notes due 2014 [Member]	Dec. 31, 2011 NVE [Member] NVE Senior Notes due 2014 [Member]	Dec. 31, 2011 NVE [Member] NVE Senior Notes due 2017 [Member]	Dec. 31, 2012 NVE [Member] NVE Senior Notes due 2020 [Member]	Dec. 31, 2011 NVE [Member] NVE Senior Notes due 2020 [Member]	Dec. 31, 2012 Nevada Power Company [Member]	Dec. 31, 2011 Nevada Power Company [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured General And Refunding Mortgage Securities Npc Series [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured General And Refunding Mortgage Securities Npc Series [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series I [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series I [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series L [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series L [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series M [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series M [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series N [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series N [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series O [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series O [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series R [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series R [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series S [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, NPC Series S [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series U [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series U [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series V [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series V [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series X [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series X [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series Y [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured, General and Refunding Mortgage Securities, Series Y [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured Variable Rate Debt NPC IDRB Series 2000A [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured Variable Rate Debt NPC IDRB Series 2000A [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured Variable Rate Debt, NPC PCRB Series 2006 [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured Variable Rate Debt, NPC PCRB Series 2006 [Member]	Dec. 31, 2012 Nevada Power Company [Member] Secured Variable Rate Debt Npc Pcrb Series 2006A [Member]	Dec. 31, 2011 Nevada Power Company [Member] Secured Variable Rate Debt Npc Pcrb Series 2006A [Member]	Dec. 31, 2012 Nevada Power Company [Member] Capital Lease Obligations [Member]	Dec. 31, 2011 Nevada Power Company [Member] Capital Lease Obligations [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member]	Dec. 31, 2011 Sierra Pacific Power Company [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member] Secured, General and Refunding Mortgage Securities, SPPC Series M [Member]	Dec. 31, 2011 Sierra Pacific Power Company [Member] Secured, General and Refunding Mortgage Securities, SPPC Series M [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member] Secured, General and Refunding Mortgage Securities, SPPC Series P [Member]	Dec. 31, 2011 Sierra Pacific Power Company [Member] Secured, General and Refunding Mortgage Securities, SPPC Series P [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member] Secured, General and Refunding Mortgage Securities, SPPC Series Q [Member]	Dec. 31, 2011 Sierra Pacific Power Company [Member] Secured, General and Refunding Mortgage Securities, SPPC Series Q [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member] Secured Variable Rate Debt Sppc Pcrb Series 2006 [Member]	Dec. 31, 2011 Sierra Pacific Power Company [Member] Secured Variable Rate Debt Sppc Pcrb Series 2006 [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member] Secured Variable Rate Debt Sppc Pcrb Series 2006 B [Member]	Dec. 31, 2011 Sierra Pacific Power Company [Member] Secured Variable Rate Debt Sppc Pcrb Series 2006 B [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member] Secured Variable Rate Debt Sppc Pcrb Series 2006 C [Member]	Dec. 31, 2011 Sierra Pacific Power Company [Member] Secured Variable Rate Debt Sppc Pcrb Series 2006 C [Member]	Dec. 31, 2012 Sierra Pacific Power Company [Member] Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Long-term debt including current maturities	$ 5,024,450		$ 130,000	$ 0	$ 250,000	$ 250,000	$ 210,000	$ 210,000	$ 370,000	$ 370,000	$ 325,000	$ 325,000	$ 350,000	$ 350,000	$ 500,000	$ 500,000	$ 125,000	$ 125,000	$ 500,000	$ 500,000	$ 250,000	$ 250,000	$ 250,000	$ 250,000	$ 450,000	$ 450,000	$ 251,742	$ 251,742	$ 250,000	$ 250,000	$ 98,100	$ 98,100	$ 37,700	$ 37,700	$ 37,975	$ 37,975	$ 58,200	$ 58,200	$ 75,000	$ 75,000	$ 81,475	$ 81,475	$ 195,000	$ 195,000	$ 315,000	$ 315,000	$ 44,258	$ 51,270	$ 510,000		$ 195,000	$ 195,000		$ 315,000	$ 315,000	$ 3,346,683				$ 0	$ 130,000	$ 250,000	$ 250,000	$ 210,000	$ 210,000	$ 370,000	$ 370,000	$ 325,000	$ 325,000	$ 350,000	$ 350,000	$ 500,000	$ 500,000	$ 125,000	$ 125,000	$ 500,000	$ 500,000	$ 250,000	$ 250,000	$ 250,000	$ 250,000	$ 98,100	$ 98,100	$ 37,700	$ 37,700	$ 37,975	$ 37,975	$ 42,908	$ 51,270	$ 1,167,767		$ 450,000	$ 450,000	$ 251,742	$ 251,742	$ 250,000	$ 250,000	$ 58,200	$ 58,200	$ 75,000	$ 75,000	$ 81,475	$ 81,475	$ 1,350
Debt Instrument, Unamortized Discount (Premium), Net	(1,631)	12,546																																																0						9,827	25,455																																	(11,458)	(12,909)
Current maturities	(356,283)	(139,985)																																																						(106,048)	(139,985)																																	(250,235)	0
Total Long-Term Debt	$ 4,669,798	$ 5,008,931																																																$ 510,000						$ 3,230,808	$ 3,319,605																																	$ 928,990	$ 1,179,326
Stated interest rate (in hundredths)			6.50%		5.875%		5.95%		6.65%		6.50%		6.75%		6.50%		7.375%		7.125%		5.375%		5.45%		6.00%		6.75%		5.45%														2.81%		6.25%								6.75%						8.25%	6.50%																				5.45%
Maturity date			2012		2015		2016		2036		2018		2037		2018		2014		2019		2040		2041		2016		2037		2013		2020		2036		2032		2031		2036		2036		2014		2020													June 1, 2011																						May 15, 2041