REGULATORY ACTIONS, FERC Matters (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Nevada Power Company [Member]
FERC Matters [Abstract]
TransmissionRateCase	$ 11.3
Sierra Pacific Power Company [Member]
FERC Matters [Abstract]
TransmissionRateCase	$ 3.2

The amount filed with the FERC to reset transmission and ancillary service rates. Amount is subject to final approval by the FERC

No definition available.