INCOME TAXES (Additional Information) (Detail) (USD $)	1 Months Ended	12 Months Ended
	Feb. 28, 2013	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Unregulated investment loss		$ (7,000,000)	$ (7,000,000)
Deferred Tax Asset Valuation Allowance		7,000,000	7,000,000
Proceeds and Excess Tax Benefit from Share-based Compensation		4,000,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate			1,000,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued		0	1,000,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		0
Unrecognized Tax Benefits, Interest on Income Taxes Expense		1,000,000	0
Reductions Based on Settlements with Tax Authorities	(28,000,000)	(28,000,000)	(4,000,000)
Change In Deferred Tax Liabilities And Deferred Tax Assets Related To Tangible Property		4,000,000
Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Operating Loss Carryforwards		266,000,000
TUCSON ELECTRIC POWER COMPANY
Income Taxes [Line Items]
Deferred Tax Asset Valuation Allowance		2,000,000	0
Reductions Based on Settlements with Tax Authorities	(22,000,000)	(22,000,000)	(4,000,000)
TUCSON ELECTRIC POWER COMPANY | Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Operating Loss Carryforwards		$ 286,000,000