CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	$ (136)	$ (89)
Market value of risk management assets and liabilities	(110)	141
Nevada Power Company [Member]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	(54)	(32)
Sierra Pacific Power Company [Member]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	$ (31)	$ (23)