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	12,173				12,173		(1,316)			(1,316)		18,644			18,644
Change in market value of risk management assets and liabilities	(246)					(246)
Change in compensation retirement benefits liability and amortization	155					155	63				63	42				42
Dividends Declared	(30,680)				(30,680)		(39,000)			(39,000)		(20,000)			(20,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2012	3,387,481	236,000		2,713,736	445,770	(8,025)	2,808,724	1	2,308,219	504,558	(4,054)	973,228	4	1,111,262	(136,696)	(1,342)
Balance (in shares) at Mar. 31, 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	21,475				21,475		5,445			5,445		21,904			21,904
Employee Benefits	12,959		11,795	1,164
Dividend Reinvestment and Employee Benefits (in shares)			644,536
Change in market value of risk management assets and liabilities	199					199
Change in compensation retirement benefits liability and amortization	246					246	97				97	59				59
Dividends Declared	(44,748)				(44,748)		(50,000)			(50,000)
Common stock repurchased	(3,651)		(3,651)
Common stock repurchaed (shares)			(197,178)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2013	$ 3,543,851	$ 236,000	$ (8,660)	$ 2,714,107	$ 612,030	$ (9,626)	$ 2,877,860	$ 1	$ 2,308,211	$ 574,057	$ (4,409)	$ 1,060,699	$ 4	$ 1,111,266	$ (49,082)	$ (1,489)
Balance (in shares) at Mar. 31, 2013	235,526,514	235,999,750	(473,236)				1,000	1,000				1,000	1,000