CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Treasury stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Nevada Power Company [Member]	Nevada Power Company [Member] Common Stock [Member]	Nevada Power Company [Member] Additional Paid-in Capital [Member]	Nevada Power Company [Member] Retained Earnings [Member]	Nevada Power Company [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Sierra Pacific Power Company [Member]	Sierra Pacific Power Company [Member] Common Stock [Member]	Sierra Pacific Power Company [Member] Additional Paid-in Capital [Member]	Sierra Pacific Power Company [Member] Retained Earnings [Member]	Sierra Pacific Power Company [Member] Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2011	$ 3,406,079	$ 236,000		$ 2,713,736	$ 464,277	$ (7,934)	$ 2,848,977	$ 1	$ 2,308,219	$ 544,874	$ (4,117)	$ 974,542	$ 4	$ 1,111,262	$ (135,340)	$ (1,384)
Balance (in shares) at Dec. 31, 2011		235,999,750						1,000					1,000
Net Income	81,612				81,612		60,981			60,981		31,323			31,323
Change in market value of risk management assets and liabilities	(475)					(475)
Change in compensation retirement benefits liability and amortization	309					309	127				127	85				85
Unrealized net gain/(loss) on investment	0
Dividends Declared	(70,800)				(70,800)		(79,000)			(79,000)		(20,000)			(20,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2012	3,416,725	236,000		2,713,736	475,089	(8,100)	2,831,085	1	2,308,219	526,855	(3,990)	985,950	4	1,111,262	(124,017)	(1,299)
Balance (in shares) at Jun. 30, 2012		235,999,750						1,000					1,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2012
Net Income	69,439						62,297					12,679
Change in market value of risk management assets and liabilities	(229)
Change in compensation retirement benefits liability and amortization	154						64					43
Unrealized net gain/(loss) on investment	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2012	3,416,725	236,000		2,713,736			2,831,085	1	2,308,219			985,950	4	1,111,262
Balance (in shares) at Jun. 30, 2012		235,999,750						1,000					1,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2012	3,557,371	236,000	(16,804)	2,712,943	635,303	(10,071)	2,922,318	1	2,308,211	618,612	(4,506)	1,038,736	4	1,111,266	(70,986)	(1,548)
Balance (in shares) at Dec. 31, 2012	235,079,156	235,999,750	(920,594)				1,000	1,000				1,000	1,000
Net Income	84,708				84,708		64,110			64,110		32,680			32,680
Employee Benefits	17,006		14,591	2,415
Dividend Reinvestment and Employee Benefits (in shares)			792,946
Change in market value of risk management assets and liabilities	496					496
Change in compensation retirement benefits liability and amortization	492					492	194				194	117				117
Unrealized net gain/(loss) on investment	(65)					(65)
Dividends Declared	(89,490)				(89,490)		(80,000)			(80,000)		(20,000)			(20,000)
Common stock repurchased	(6,329)		(6,329)
Common stock repurchaed (shares)			(325,178)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2013	3,564,189	236,000	(8,542)	2,715,358	630,521	(9,148)	2,906,622	1	2,308,211	602,722	(4,312)	1,051,533	4	1,111,266	(58,306)	(1,431)
Balance (in shares) at Jun. 30, 2013	235,546,924	235,999,750	(452,826)				1,000	1,000				1,000	1,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2013
Net Income	63,233						58,665					10,776
Change in market value of risk management assets and liabilities	297
Change in compensation retirement benefits liability and amortization	246						97					58
Unrealized net gain/(loss) on investment	(65)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2013	$ 3,564,189	$ 236,000					$ 2,906,622	$ 1	$ 2,308,211			$ 1,051,533	$ 4	$ 1,111,266
Balance (in shares) at Jun. 30, 2013	235,546,924	235,999,750					1,000	1,000				1,000	1,000