REGULATORY MATTERS (Summary of PPFAC Rates) (Detail)	3 Months Ended	6 Months Ended		9 Months Ended	3 Months Ended	6 Months Ended		9 Months Ended	3 Months Ended		6 Months Ended				9 Months Ended		3 Months Ended	4 Months Ended	5 Months Ended		7 Months Ended
	Mar. 31, 2012 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY	Jun. 30, 2013 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY	Mar. 31, 2012 TUCSON ELECTRIC POWER COMPANY PPFAC [Member]	Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY PPFAC [Member]	Jun. 30, 2013 TUCSON ELECTRIC POWER COMPANY PPFAC [Member]	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY PPFAC [Member]	Mar. 31, 2012 TUCSON ELECTRIC POWER COMPANY CTC [Member]		Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY CTC [Member]		Jun. 30, 2013 TUCSON ELECTRIC POWER COMPANY CTC [Member]		Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY CTC [Member]		Aug. 31, 2013 UNS Electric	Dec. 31, 2013 UNS Electric	May 31, 2013 UNS Electric	May 31, 2012 UNS Electric	Dec. 31, 2012 UNS Electric
Schedule of Regulatory Matters Summary Of PPFAC Rates [Table] [Line Items]
PPFAC Rates	0.0000	0.0014	0.0077	0.0077	0.0053	0.0014	0.0077	0.0077	(0.0053)	[1]	0.0000	[1]	0.0000	[1]	0.0000	[1]	(0.0092)	(0.0040)	(0.0144)	(0.0088)	(0.0144)

[1] TEP's PPFAC became effective January 1, 2009. However, TEP was initially required to refund amounts to customers through the PPFAC mechanism that were over collected under the Competition Transition Charge (CTC) in place from 1999 through 2008. As a result, the authorized net PPFAC charge was set at zero until all over collected CTC revenue was fully refunded to customers (November 2011). TEP then continued deferring PPFAC eligible costs but was not authorized to bill customers until a new PPFAC rate was approved by the ACC in April 2012.