Regulatory Matters (Details Textual) (USD $)	3 Months Ended	9 Months Ended			9 Months Ended		1 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2011	Sep. 30, 2010	Jun. 30, 2011	Sep. 30, 2011 Subsidiaries [Member]	Sep. 30, 2010 Subsidiaries [Member]	Apr. 30, 2011 UNS GAS, INC. [Member]	Sep. 30, 2011 UNS GAS, INC. [Member]	Dec. 31, 2012 UNS GAS, INC. [Member]	Jun. 30, 2011 UNS ELECTRIC, INC. [Member]
Regulatory Matters (Textual) [Abstract]
Gas is required to request approval of a surcredit when the PGA bank balance exceeds								$ 10,000,000
Revenue refunded	16,000,000	30,652,000	8,152,000		30,652,000	8,152,000
Increase to fuel and purchased power expense	1,000,000
Percentage rate increase requested with regulator							3.80%
Revenue Deficiency Covered in General Rate Case With Acc							5,600,000
Expected reduction in annual depreciation expense due to change in depreciation rates									1,000,000
FERC approved actual purchase price of BMGS										63,000,000
Revenue-neutral rate reclassification from base power supply rate to non-fuel base rates				$ 0.7