SHARE-BASED COMPENSATION PLANS (Additional Information) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense, net of amounts capitalized	$ 1	$ 1	$ 2	$ 1
Total unrecognized compensation expense on non-vested share-based compensation	5		5
Number Of Shares Awarded But Not Yet Issued	500,000		500,000
TUCSON ELECTRIC POWER COMPANY
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense, net of amounts capitalized	1	1	1	1
Total unrecognized compensation expense on non-vested share-based compensation	$ 4		$ 4