Commitments Contingencies and Proposed Environmental Matters (Details Textual) (USD $)	1 Months Ended	3 Months Ended			9 Months Ended			9 Months Ended		1 Months Ended	3 Months Ended		9 Months Ended				9 Months Ended
	Sep. 30, 2011	Dec. 31, 2011 MWh	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 MWh Ton kV mi	Sep. 30, 2010	Sep. 30, 2011 UNS GAS, INC. [Member]	Sep. 30, 2011 UNS ELECTRIC, INC. [Member]	Sep. 30, 2011 UNS ELECTRIC, INC. [Member] Purchased Power [Member]	Dec. 31, 2008 TEP [Member]	Sep. 30, 2011 TEP [Member]	Sep. 30, 2010 TEP [Member]	Sep. 30, 2011 TEP [Member]	Sep. 30, 2010 TEP [Member]	Dec. 31, 2010 TEP [Member]	Sep. 30, 2011 TEP [Member] Purchased Power [Member]	Sep. 30, 2011 TEP [Member] Maximum [Member]	Sep. 30, 2011 TEP [Member] Minimum [Member]	Sep. 30, 2011 TEP [Member] TEP Contingencies [Member]	Sep. 30, 2011 Four Corner [Member]
Commitments and Contingencies (Textual) [Abstract]
2011									$ 1,000,000		$ 52,000,000		$ 52,000,000			$ 3,000,000
2012							3,000,000		20,000,000		79,000,000		79,000,000			23,000,000
2013							2,000,000		24,000,000		50,000,000		50,000,000			20,000,000
2014							3,000,000		35,000,000		39,000,000		39,000,000			21,000,000
2015									3,000,000		16,000,000		16,000,000			12,000,000
Thereafter									46,000,000		204,000,000		204,000,000			196,000,000
Total									129,000,000		440,000,000		440,000,000			275,000,000
Amount spent on acquired Land and development of headquarter	59,000,000
Commitment Outstanding	10,000,000		10,000,000		10,000,000
Minimum Transport Quantity					2,400,000
Commitment to purchase photovoltaic equipment having capacity					9
Obligation to purchase percentage of output facility under renewable energy PPA								100.00%					100.00%
Commitment to purchase photovoltaic equipment having MW capacity remain to ACC		6
Commitment to purchase photovoltaic equipment having MW capacity approved by ACC		3
Amount refunded by El Paso for transmission service to TEP										11,000,000
TEP's rights for transmission before settlement of exchange agreement					200
Rights for Transmission After Settlement of Exchange Agreement					170
Transmission for the amount					30
New firm transmission capacity					40
Settlement amount to be paid by TEP to El Paso under Exchange Agreement													5,000,000
Additional transmission expenses TEP would be allowed to recover from retail customers under the PPFAC mechanism											2,000,000
Term of purchase agreement with Macho Springs facility													P20Y
Pre tax gain to be recognized if settlement agreements are approved by FERC											7,000,000		7,000,000
Net reduction to transmission expense													7,100,000
Interest income																			900,000
Interest Expense			28,105,000	25,818,000	83,230,000	80,895,000					22,285,000	20,154,000	65,719,000	63,732,000					600,000
TEP's share of the reclamation costs at the expiration dates of coal supply agreement													26,000,000
TEP's recorded obligation for final mine reclamation costs											13,000,000		13,000,000		11,000,000
DC lawsuit seeking damages													600,000,000
DC Lawsuit Seeking Punitive Damages													Not less than 1 billion
Percentage of ownership of San Juan units 1 and 2					50.00%								7.50%
Percentage of ownership in total generation capacity					20.00%
Share of any resulting liabilities					7.00%
Forecasted consumption levels					Eight and one-half months
Term of advance notice for Lawsuit																				P60D
Approximate Mileage of Transmission line from Tucson to Nogales					60
Transmission line approved by ACC, in KV					345
TEP Capitalized Amount related to Nogales transmission line project											11,000,000		11,000,000		11,000,000
Land and Land Rights Related to Nogales Transmission Line											2,000,000		2,000,000		2,000,000
Estimated Capital cost for mercury emission control equipment for Springerville Units 1 and 2	3,000,000		3,000,000		3,000,000
Estimated Annual Operating Expenses for mercury emission control equipment for Springerville Units 1 and 2					5,000,000
TEP's share of capital expenditures related to installation of SCRs at SJ																	202,000,000	155,000,000
TEP's Share of the Estimated Capital Cost for Mercury Control Equipment for Navajo					Less than 1 million
TEP's Estimated share of capital expenditure related to installation of SCRs for units 4 and 5													35,000,000
TEP's estimated capital cost if SCR is required at Navajo													42,000,000
TEP's capital expenditure related to installation of baghouses at Navajo													$ 43,000,000