CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
OTHER INCOME (EXPENSE):
AFUDC-debt	$ 2,131	$ 1,595
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
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 INCOME (EXPENSE):
AFUDC-debt	1,837	1,179
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	(54)	(32)
Sierra Pacific Power Company [Member]
OTHER INCOME (EXPENSE):
AFUDC-debt	294	416
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	$ (31)	$ (23)