COMMON STOCK AND OTHER PAID IN CAPITAL (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Dividends Payable [Line Items]
Dividends Declared Per Share of Common Stock	$ 0.17	$ 0.12	$ 0.47	$ 0.36
Treasury Stock [Abstract]
treasury stock value	$ 4,509,000		$ 4,509,000		$ 0
Treasury stock shares	(252,000)		(252,000)		0
Parent Company [Member] | First Declaration [Member]
Dividends Payable [Line Items]
Dividends Declared Per Share of Common Stock			$ 0.13
Dividends [Abstract]
Declaration date			Feb. 10, 2012
Dividends Payable, Date to be Paid, Day, Month and Year			Mar. 21, 2012
Dividends Payable, Date of Record, Day, Month and Year			Mar. 06, 2013
Parent Company [Member] | Second Declaration [Member]
Dividends Payable [Line Items]
Dividends Declared Per Share of Common Stock			$ 0.17
Dividends [Abstract]
Declaration date			May 07, 2012
Dividends Payable, Date to be Paid, Day, Month and Year			Jun. 20, 2012
Dividends Payable, Date of Record, Day, Month and Year			Jun. 05, 2012
Parent Company [Member] | Third Declaration [Member]
Dividends Payable [Line Items]
Dividends Declared Per Share of Common Stock			$ 0.17
Dividends [Abstract]
Declaration date			Aug. 02, 2012
Dividends Payable, Date to be Paid, Day, Month and Year			Sep. 19, 2012
Dividends Payable, Date of Record, Day, Month and Year			Sep. 04, 2012
Parent Company [Member] | Fourth Declaration [Member]
Dividends Payable [Line Items]
Dividends Declared Per Share of Common Stock			$ 0.17
Dividends [Abstract]
Declaration date			Nov. 07, 2012
Dividends Payable, Date to be Paid, Day, Month and Year			Dec. 19, 2012
Dividends Payable, Date of Record, Day, Month and Year			Dec. 04, 2012
Nevada Power Company [Member]
Dividends [Abstract]
Declaration date			Nov. 07, 2012
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			119,000,000
Dividend declared to parent company			65,000,000
Sierra Pacific Power Company [Member]
Dividends [Abstract]
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			$ 20,000,000