DEBT, CREDIT FACILITIES, AND CAPITAL LEASE OBLIGATIONS (Capital Leases) (Details) (TUCSON ELECTRIC POWER COMPANY, Springerville Coal Handling Facilities Lease [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2014
TUCSON ELECTRIC POWER COMPANY | Springerville Coal Handling Facilities Lease [Member]
Debt Instrument [Line Items]
Increase in Capital Lease Obligation	$ 109
Fixed price to acquire leased interest in facilities	120
Increase in utility plant under capital lease	109
Sales Price of Leased Interest In Facilities	$ 24