REGULATORY MATTERS (Regulatory Assets and Liabilities) (Detail) (TUCSON ELECTRIC POWER COMPANY, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
TUCSON ELECTRIC POWER COMPANY
Regulatory Assets And Liabilities [Line Items]
Mine Fire Cost Deferral	$ 10
Mine Fire Insurance Settlement Proceeds	$ 5