COMMITMENTS, CONTINGENCIES, AND ENVIRONMENTAL MATTERS (Environmental Matters) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Navajo [Member]
Commitments And Contingencies [Line Items]
Estimated Future Capital Cost For Mercury Emission Control Equipment	$ 1,000,000
Estimated Future Annual Operating Costs for Mercury Emission Control Equipment	1,000,000
Estimated Capital Expenditure for Selective Catalytic Reduction	42,000,000	[1]
Estimated Capital Expenditure for Selective Non Catalytic Reduction	0	[1]
Estimated Future Change in Operating Cost for Selective Catalytic Reduction	1,000,000	[1]
Estimated Future Change in Operating Cost for Selective Non Catalytic Reduction	0	[1]
Better Than BART Agreement Year by which to Shut Down One Unit	2020
Better than BART Agreement, Year by which SCR Technology to be Installed	2030
Better than BART Agreement, Year by which Coal Fired Operation will Cease	2044
Estimated Capital Expenditure Related to Installation of Baghouses	43,000,000
Estimated Future Annual Operating Costs For Mercury Emmission Control Equipment and Baghouses	1,000,000
San Juan Unit Two [Member]
Commitments And Contingencies [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%
Four Corner [Member]
Commitments And Contingencies [Line Items]
Estimated Future Capital Cost For Mercury Emission Control Equipment	1,000,000
Estimated Future Annual Operating Costs for Mercury Emission Control Equipment	1,000,000
Estimated Capital Expenditure for Selective Catalytic Reduction	35,000,000	[2]
Estimated Capital Expenditure for Selective Non Catalytic Reduction	0	[2]
Estimated Future Change in Operating Cost for Selective Catalytic Reduction	2,000,000	[2]
Estimated Future Change in Operating Cost for Selective Non Catalytic Reduction	0	[2]
Jointly Owned Utility Plant, Proportionate Ownership Share	7.00%
Springerville [Member]
Commitments And Contingencies [Line Items]
Estimated Future Capital Cost For Mercury Emission Control Equipment	5,000,000
Estimated Future Annual Operating Costs for Mercury Emission Control Equipment	3,000,000
San Juan [Member]
Commitments And Contingencies [Line Items]
Estimated Capital Expenditure for Selective Non Catalytic Reduction	35,000,000	[3]
Estimated Future Change in Operating Cost for Selective Catalytic Reduction	6,000,000	[3]
Estimated Future Change in Operating Cost for Selective Non Catalytic Reduction	1,000,000	[3]
Jointly Owned Utility Plant, Proportionate Ownership Share	20.00%
Book Value of Company Share Of Generating Units	113,000,000
San Juan [Member] | Minimum [Member]
Commitments And Contingencies [Line Items]
Estimated Capital Expenditure for Selective Catalytic Reduction	180,000,000
San Juan [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Estimated Capital Expenditure for Selective Catalytic Reduction	200,000,000
Sundt [Member]
Commitments And Contingencies [Line Items]
Estimated Capital Expenditure for Selective Catalytic Reduction	0	[2]
Estimated Capital Expenditure for Selective Non Catalytic Reduction	12,000,000	[2]
Estimated Future Change in Operating Cost for Selective Catalytic Reduction	0	[2]
Sundt [Member] | Minimum [Member]
Commitments And Contingencies [Line Items]
Estimated Future Change in Operating Cost for Selective Non Catalytic Reduction	5,000,000	[2]
Sundt [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Estimated Future Change in Operating Cost for Selective Non Catalytic Reduction	6,000,000	[2]
TUCSON ELECTRIC POWER COMPANY
Commitments And Contingencies [Line Items]
Environmental compliance costs capitalized in construction costs	5,000,000		2,000,000	8,000,000
Environmental Remediation Expense	8,000,000		15,000,000	12,000,000
Expected environmental expenses	5,000,000
TUCSON ELECTRIC POWER COMPANY | Sundt [Member]
Commitments And Contingencies [Line Items]
Book Value of Company Share Of Generating Units	27,000,000
TUCSON ELECTRIC POWER COMPANY | One Year In Future [Member]
Commitments And Contingencies [Line Items]
Expected environmental compliance costs to be capitalized in construction costs	12,000,000
TUCSON ELECTRIC POWER COMPANY | Two Years In Future [Member] [Member]
Commitments And Contingencies [Line Items]
Expected environmental compliance costs to be capitalized in construction costs	$ 36,000,000

[1] The EPA is considering a better-than-BART plan wherein: one unit at Navajo will be shut down by 2020; SCR installation (or the equivalent) will be installed on the remaining two units by 2030; and conventional coal-fired generation will cease by December 2044. TEP expects the EPA to reach a decision in 2014. In addition, the installation of SCR technology could increase particulates which may require that baghouses be installed. The additional capital cost of baghouses approximates $43 million with O&M on the baghouses expected to be less than $1 million per year.

[2] On December 30, 2013, APS, on behalf of the co-owners of Four Corners, notified the EPA that they have chosen the alternative BART compliance strategy; APS closed Units 1, 2, and 3 in December 2013 and has agreed to the installation of SCR on Units 4 & 5 by July 31, 2018. TEP owns 7% of Four Corners Units 4 and 5.

[3] The Federal Implementation Plan (FIP) requires SCR; as part of a proposal for an alternative, PNM, the State of New Mexico, and the EPA signed a non-binding agreement in which PNM agreed to close Units 2 & 3 by December 31, 2017 and install SNCRs on Units 1 & 4 by January 2016 or later. The State of New Mexico has submitted this plan to the EPA for approval. TEP expects the EPA will reach a decision in 2014. TEP owns 50% of San Juan Unit 2. At December 31, 2013, the net book value of TEP's share in San Juan Unit 2 was $113 million. If Unit 2 is retired early, we expect to request ACC approval to recover, over a reasonable time period, all costs associated with the early closure of the unit.