STOCKHOLDERS' EQUITY (Additional Information) (Detail) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended							1 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2011 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2012 Convertible Debt [Member] UNS Energy	Feb. 25, 2014 Subsequent Event [Member]
Class of Stock [Line Items]
Dividends declared (usd per share)	$ 1.74	$ 1.72	$ 1.68					$ 0.48
Dividend payable								$ 20,000,000
Converted notes principal							147,000,000
UNS Energy common stock							4,300
Dividends paid to UNS energy				40,000,000	30,000,000	0
Equity investment from parent	$ 0	$ 0	$ 30,000,000	$ 0	$ 0	$ 30,000,000