DEBT, CREDIT FACILITIES, AND CAPITAL LEASE OBLIGATIONS (Detail) (USD $)	12 Months Ended						1 Months Ended			12 Months Ended				12 Months Ended			1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended								12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2011 TUCSON ELECTRIC POWER COMPANY	Apr. 30, 2013 TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Jun. 30, 2012 TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Mar. 31, 2012 TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Mar. 31, 2013 TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Sep. 30, 2012 TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY Springerville Common Facilities Lease Debt [Member]	Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY Variable Rate Demand Obligation [Member]	Dec. 31, 2010 TUCSON ELECTRIC POWER COMPANY Variable Rate Demand Obligation [Member]	Aug. 31, 2009 TUCSON ELECTRIC POWER COMPANY Variable Rate Demand Obligation [Member]	Aug. 31, 2011 UNS ELECTRIC, INC. Uns Electric Term Loan [Member]	Dec. 31, 2012 Parent [Member] Convertible Debt [Member]	Dec. 31, 2005 Parent [Member] Convertible Debt [Member]	Sep. 30, 2012 Revolving Credit Facility [Member] TUCSON ELECTRIC POWER COMPANY Line of Credit [Member]	Dec. 31, 2013 Revolving Credit Facility [Member] TUCSON ELECTRIC POWER COMPANY Line of Credit [Member]	Dec. 31, 2013 Revolving Credit Facility [Member] Parent [Member] Line of Credit [Member]	Dec. 31, 2013 Letter of Credit [Member] TUCSON ELECTRIC POWER COMPANY Line of Credit [Member]	Jun. 30, 2012 Minimum [Member] TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Mar. 31, 2012 Minimum [Member] TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Jun. 30, 2012 Maximum [Member] TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Mar. 31, 2012 Maximum [Member] TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Oct. 31, 2013 Collateralized Mortgage Backed Securities [Member] TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2013 Variable Rate Bonds [Member] TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]	Nov. 30, 2013 Variable Rate Bonds [Member] TUCSON ELECTRIC POWER COMPANY Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt instrument, face amount								$ 16,000,000	$ 177,000,000		$ 91,000,000	$ 150,000,000		$ 115,000,000	$ 37,000,000		$ 30,000,000		$ 150,000,000											$ 100,000,000
Fixed interest rate of long-term debt							6.375%	4.50%	4.50%		4.00%	3.85%							4.50%					5.85%	5.85%	5.875%	5.875%
Repayments of convertible debt																		3,000,000
Amount of 1992 mortgage bonds used to secure letter of credit facilities																												423,000,000
Derivative amount of hedged item																50,000,000
Fixed rate of interest related to interest rate swap																2.40%	0.97%
Derivative basis spread													1.75%
Repayment of outstanding credit facility	108,000,000	381,000,000	351,000,000	78,000,000	199,000,000	210,000,000														72,000,000
Repayments of long-term debt	0	9,341,000	252,125,000	0	6,535,000	172,460,000			7,000,000
Debt extinguishment							91,000,000	16,000,000	184,000,000	193,000,000				100,000,000
Accrued interest portion on debt repayment									1,000,000
Effective interest rate																													0.948%
Term of debt																	4 years												5 years
Debt instrument																	$ 30,000,000
Interest rate spread on LIBOR borrowing																	1.125%				1.125%	1.25%	1.125%