REGULATORY MATTERS (Cost Recovery Mechanisms) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended	1 Months Ended				12 Months Ended			1 Months Ended		12 Months Ended
	Jun. 30, 2013 UNS Gas	Dec. 31, 2013 UNS Gas	Oct. 31, 2013 UNS Gas Before November 1, 2013 [Member]	Oct. 31, 2013 UNS Gas From November 1, 2013 through April 30, 2014 [Member]	Oct. 31, 2013 TUCSON ELECTRIC POWER COMPANY	Jun. 30, 2013 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2011 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2013 UNS Electric	Oct. 31, 2013 UNS Electric	Dec. 31, 2013 UNS Electric	Dec. 31, 2012 UNS Electric	Dec. 31, 2013 Minimum [Member] UNS Gas	Dec. 31, 2012 Minimum [Member] UNS Gas	Dec. 31, 2013 Maximum [Member] UNS Gas	Dec. 31, 2012 Maximum [Member] UNS Gas
Schedule of Regulatory Cost Recovery Mechanisms [Line Items]
Increase (Decrease) of PPFAC												0.83
Deferral balance										$ 10		$ 10
PPFAC balance over-collected										14		14
Factor automatically adjusts restricted from rising or falling in twelve month period		0.15
Gas Is Required To Request Approval Of Surcredit When Pga Bank Balance Exceeds		10
Purchased Gas Adjustor Credit			0.045	0.10
Customer refund liability, current		10
Purchased gas adjustor rate														0.4504	0.5202	0.5280	0.6501
Approved Investment Cost By ACC To Invest In Owned Solar Projects					40						7
Proposed Collections From Customers For Renewable Energy Programs					34						6
Amount receivable as return on investment							2.0	2.0	1.0			0.5	0.5
Approved energy efficiency budget	$ 2					$ 21				$ 5
Retail revenue cap on environmental compliance adjustor						0.25%
Cap on increase in lost fixed cost recovery rate						1.00%