INCOME TAXES (Differences between Income Tax Expense and Amount Obtained by Multiplying Pre-Tax Income by U.S. Statutory Federal Income Tax Rate) (Detail) (USD $)	1 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Statutory tax rate		35.00%
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount		$ 65,000,000	$ 51,000,000	$ 62,000,000
State Income Tax Expense, Net of Federal Deduction		8,000,000	7,000,000	8,000,000
Federal/State Tax Credits		(2,000,000)	(1,000,000)	(3,000,000)
Allowance for Funds Used During Construction Income Tax Difference		(2,000,000)	(1,000,000)	(1,000,000)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		0	0	0
Investment Tax Credit Basis Difference	(11,039,000)		0	0
Other		0	0	1,000,000
Income Tax Expense (Benefit)		58,427,000	55,727,000	66,951,000
TUCSON ELECTRIC POWER COMPANY
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount		52,000,000	37,000,000	48,000,000
State Income Tax Expense, Net of Federal Deduction		7,000,000	5,000,000	6,000,000
Federal/State Tax Credits		(2,000,000)	(1,000,000)	(2,000,000)
Allowance for Funds Used During Construction Income Tax Difference		(1,000,000)	(1,000,000)	(1,000,000)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		2,000,000	0	0
Investment Tax Credit Basis Difference		(10,751,000)	0	0
Other		1,000,000	(1,000,000)	1,000,000
Income Tax Expense (Benefit)		$ 47,986,000	$ 39,109,000	$ 52,000,000