FAIR VALUE MEASUREMENTS & DERIVATIVE INSTRUMENTS (Derivative Volumes) (Details)	Dec. 31, 2013 GWh	Dec. 31, 2012 GWh
Power Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives Volumes	1,583	2,228
Gas Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives Volumes	33,371,000,000	17,851,000,000
TUCSON ELECTRIC POWER COMPANY | Power Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives Volumes	779	820
TUCSON ELECTRIC POWER COMPANY | Gas Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives Volumes	9,615,000,000	7,958,000,000