CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (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 INCOME (EXPENSE):
AFUDC-debt	$ 1,682	$ 1,908	$ 3,813	$ 3,503
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
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 INCOME (EXPENSE):
AFUDC-debt	1,406	1,314	3,243	2,493
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	(50)	(38)	(104)	(70)
Sierra Pacific Power Company [Member]
OTHER INCOME (EXPENSE):
AFUDC-debt	276	594	570	1,010
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	$ (32)	$ (23)	$ (63)	$ (46)