Regulatory Matters (Details) (USD $)	2 Months Ended		3 Months Ended		4 Months Ended
	May 31, 2011	May 31, 2010	Mar. 31, 2011	Mar. 31, 2010	Sep. 30, 2011	Sep. 30, 2010
TEP [Member] | PPFAC [Member]
Summary of PPFAC and PGA Rates
PPFAC Rates	$ 0.53	$ 0.09	$ 0.09	$ 0.18	$ 0.53	$ 0.09
TEP [Member] | CTC [Member]
Summary of PPFAC and PGA Rates
PPFAC Rates	(0.53)	(0.09)	(0.09)	(0.18)	(0.53)	(0.09)
UNS GAS, INC. [Member]
Summary of PPFAC and PGA Rates
PGA rates of UNS Gas in cents per therm		(8.00)		(8.00)		(8.00)
UNS ELECTRIC, INC. [Member]
Summary of PPFAC and PGA Rates
PPFAC Rates	$ 0.08	$ (1.06)	$ 0.08	$ (1.06)	$ (0.88)	$ (0.28)