CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	$ (129)	$ (83)	$ (265)	$ (172)
Market value of risk management assets and liabilities	3	123	(107)	264
Unrealized net gain/(loss) on investments	31	0	31	0
Nevada Power Company [Member]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	(50)	(38)	(104)	(70)
Sierra Pacific Power Company [Member]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	$ (32)	$ (23)	$ (63)	$ (46)