INCOME TAXES (Uncertain Tax Positions) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Feb. 28, 2013	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, Beginning of Year		$ 30	$ 29
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions		2	5
Reductions Based on Settlements with Tax Authorities	(28)	(28)	(4)
Unrecognized Tax Benefits, End of Year		4	30
TUCSON ELECTRIC POWER COMPANY
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, Beginning of Year		23	24
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions		1	3
Reductions Based on Settlements with Tax Authorities	(22)	(22)	(4)
Unrecognized Tax Benefits, End of Year		$ 2	$ 23