COMMON STOCK AND OTHER PAID-IN CAPITAL (Details) (USD $)	3 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Mar. 31, 2012
Dividends Payable [Line Items]
Dividends Declared Per Share of Common Stock	$ 0.19	$ 0.19	$ 0.13
Dividends [Abstract]
Dividends Payable, Date to be Paid, Day, Month and Year	Jun. 19, 2013	Mar. 20, 2013
Dividends Payable, Date of Record, Day, Month and Year	Jun. 04, 2013	Mar. 05, 2013
Declaration date	May 08, 2013	Feb. 07, 2013
Common stock repurchased		$ (3,651,000)
Treasury stock [Member]
Dividends [Abstract]
Common stock repurchaed (shares)		(197,178)
Common stock repurchased		(3,651,000)
Dividend Reinvestment and Employee Benefits (in shares)		644,536
Nevada Power Company [Member]
Dividends [Abstract]
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		50,000,000
Dividend declared to parent company		30,000,000
Declaration date		May 08, 2013
Sierra Pacific Power Company [Member]
Dividends [Abstract]
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		0
Dividend declared to parent company		$ 20,000,000
Declaration date		May 08, 2013