RELATED PARTY TRANSACTIONS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction, Due from (to) Related Parties [Abstract]
Receivable from Related Parties	$ 9,000,000	$ 7,000,000
Payable to Related Parties	2,000,000	6,000,000
Contribution from Parent	0	180,000,000	$ 225,000,000
Dividends Declared to Parent	(50,000,000)	(50,000,000)	(40,000,000)
Dividends Paid to Parent	(50,000,000)	(50,000,000)	(40,000,000)
Transmission Sales To UNS Electric [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Wholesale Sales from Related Parties	7,000,000	6,000,000	1,000,000
Wholesale Sales to UNS Electric [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Wholesale Sales from Related Parties	0	2,000,000	3,000,000
Tucson Electric Power Company To Uns Electric [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Control Area Services, Other Revenues from Transactions with Related Parties	2,000,000	2,000,000	3,000,000
TEP to UNS Energy Affiliates [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Common Costs Charged to Related Parties	14,000,000	12,000,000	13,000,000
Uns Electric To Tucson Electric Power Company [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Wholesale Revenues	1,000,000	1,000,000	4,000,000
Southwest Energy Solutions, Inc. to TEP [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Supplemental Workforce	14,000,000	16,000,000	16,000,000
UNS Energy to TEP [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Corporate Services	$ 7,000,000	7,000,000	14,000,000
Intercompany Allocation Parent to Subsidiary	82.00%
Management fee	$ 6,000,000	5,000,000
Contribution from Parent	0	180,000,000	225,000,000
UNS Energy Affiliates to TEP [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Corporate Services	4,000,000	1,000,000	$ 1,000,000
UNS Electric [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Receivable from Related Parties	7,000,000	6,000,000
Payable to Related Parties	0	2,000,000
Uns Gas [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Receivable from Related Parties	2,000,000	1,000,000
Southwest Energy Solutions, Inc. [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Payable to Related Parties	2,000,000	2,000,000
Uns Energy Corporation [Member]
Related Party Transaction, Due from (to) Related Parties [Abstract]
Payable to Related Parties	$ 0	$ 2,000,000