Document and Entity Information (USD $)	9 Months Ended
	Sep. 30, 2011	Oct. 20, 2011	Jun. 30, 2010
Entity Registrant Name	UNISOURCE ENERGY CORP
Entity Central Index Key	0000941138
Document Type	10-Q
Document Period End Date	Sep. 30, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 1,082,660,902
Entity Common Stock, Shares Outstanding		36,922,643
TEP [Member]
Entity Registrant Name	TUCSON ELECTRIC POWER COMPANY
Document Type	10-Q
Document Period End Date	Sep. 30, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	No
Entity Common Stock, Shares Outstanding	0	32,139,434