REGULATORY ACTIONS, FERC Matters (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Nevada Power Company [Member] | FERC Filing 2012 [Member]
FERC Matters [Abstract]
TransmissionRateCase	$ 11.3
Transmission Rate Case Filing Date	October 2012
Anticipated Effective Date of Rate Filing	June 1, 2013
Nevada Power Company [Member] | FERC Filing 2013 [Member]
FERC Matters [Abstract]
Transmission Rate Case Filing Date	May 2013
Anticipated Effective Date of Rate Filing	January 1, 2014
Intervenor Filing Date	July 16, 2013
Sierra Pacific Power Company [Member] | FERC Filing 2012 [Member]
FERC Matters [Abstract]
TransmissionRateCase	$ 1.5
Transmission Rate Case Filing Date	October 2012
Anticipated Effective Date of Rate Filing	June 1, 2013
Sierra Pacific Power Company [Member] | FERC Filing 2013 [Member]
FERC Matters [Abstract]
Transmission Rate Case Filing Date	May 2013
Anticipated Effective Date of Rate Filing	January 1, 2014
Intervenor Filing Date	July 16, 2013