INCOME TAXES (Summary of Tax Carryforwards) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Income Tax Contingency [Line Items]
Capital Loss	$ 7
Investment Tax Credits	6
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Net Operating Loss Carryforward	266
State Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Net Operating Loss Carryforward	30
Tax Credits	5
AMT Credit [Member]
Income Tax Contingency [Line Items]
Tax Credits	43
TUCSON ELECTRIC POWER COMPANY
Income Tax Contingency [Line Items]
Capital Loss	0
Investment Tax Credits	6
TUCSON ELECTRIC POWER COMPANY | Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Net Operating Loss Carryforward	286
TUCSON ELECTRIC POWER COMPANY | State Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Net Operating Loss Carryforward	99
Tax Credits	6
TUCSON ELECTRIC POWER COMPANY | AMT Credit [Member]
Income Tax Contingency [Line Items]
Tax Credits	$ 24