UTILITY PLANT AND JOINTLY-OWNED FACILITES (Amount of Lease Expense Incurred for TEP's Generation-Related Capital Leases) (Detail) (TUCSON ELECTRIC POWER COMPANY, USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest Expense - Included in:
Interest Expense	$ 25,140,000	$ 33,613,000	$ 40,358,000
Total Lease Expense	47,000,000	55,000,000	62,000,000
Operating Expenses - Fuel
Interest Expense - Included in:
Interest Expense	2,000,000	3,000,000	4,000,000
Amortization of Capital Lease Assets	5,000,000	4,000,000	3,000,000
Other Expense [Member]
Interest Expense - Included in:
Interest Expense	0	0	1,000,000
Operating Expenses - Amortization [Member]
Interest Expense - Included in:
Amortization of Capital Lease Assets	$ 15,000,000	$ 14,000,000	$ 14,000,000