DEBT, CREDIT FACILITIES, AND CAPITAL LEASE OBLIGATIONS (Maturities of Long-term Debt) (Detail) (USD $) In Thousands, unless otherwise specified											12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 UNS Gas	Dec. 31, 2013 UNS ELECTRIC, INC.	Dec. 31, 2013 UNS Energy	Dec. 31, 2013 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2012 TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2013 Capital Lease Obligations [Member] TUCSON ELECTRIC POWER COMPANY	Dec. 31, 2013 Long-term Debt [Member] TUCSON ELECTRIC POWER COMPANY		Dec. 31, 2013 Variable Rate Bonds [Member] Unsecured Debt [Member] TUCSON ELECTRIC POWER COMPANY
Schedule Of Maturities Of Long Term Debt [Line Items]
Term of debt instruments											5 years
2014	$ 214		$ 0	$ 0	$ 0	$ 214		$ 214	$ 0	[1]
2015	199		50	80	0	69		69	0	[1]
2016	149		0	0	54	95		17	78	[1]
2017	18		0	0	0	18		18	0	[1]
2018	111		0	0	0	111		11	100	[1]
Total 2014 - 2018	691		50	80	54	507		329	178	[1]
Thereafter	1,176		50	50	0	1,076		30	1,046	[1]
Less: Imputed Interest	(42)		0	0	0	(42)		(42)	0	[1]
Long-term Debt and Capital Lease Obligations	1,825					1,541
Total	$ 1,507,070	$ 1,498,442	$ 100	$ 130	$ 54	$ 1,223,070	$ 1,223,442	$ 317	$ 1,224	[1]

[1] $115 million of TEP’s variable rate bonds are backed by LOCs issued pursuant to TEP’s Credit Agreement, which expires in November 2016, and TEP’s Reimbursement Agreement, which expires in December 2019. Although the variable rate bonds mature between 2022 and 2032, the above table reflects a redemption or repurchase of such bonds in 2016 and 2019 as though the LOCs terminate without replacement upon expiration of the TEP Credit Agreement. TEP's 2013 tax-exempt variable rate IDBs, which mature in 2032, are subject to mandatory tender for purchase after the current five-year term and are therefore reflected as maturing in 2018. The repayment of TEP Unsecured Notes is not reduced by the approximately $1 million discount.