Approximate Mileage of transmission line from one to another city.

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- Definition

Company share of reclamation costs at expiration dates of coal supply agreement.

+ References

No definition available.

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- Definition

Percentage of ownership in generating units.

+ References

No definition available.

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- Definition

The voltage of a transmission line project.

+ References

No definition available.

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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 30

-Section 50

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-Topic 450

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-Section 25

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Topic 360

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 360

-Section S99

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-Subparagraph (SAB TOPIC 10.C)

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section C

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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

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- Definition

Amount of a reclamation and mine closing liability that is associated with a legal obligation for the closure and reclamation of a mine including the removal of buildings, equipment, machinery and other physical remnants of mining, closure of tailings impoundments, leach pads and other mine features, and contouring, covering and revegetation of waste rock piles and other disturbed areas.

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-Topic 450

-SubTopic 20

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-Paragraph 1

-Subparagraph (SAB TOPIC 5.Y.Q2)

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- Definition

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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COMMITMENTS, CONTINGENCIES, AND ENVIRONMENTAL MATTERS (TEP Contingencies) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013
San Juan [Member]
Commitments And Contingencies [Line Items]
Percentage of ownership in Generating Units 1 & 2		50.00%
Percentage of ownership in generating station		20.00%
Four Corner [Member]
Commitments And Contingencies [Line Items]
Percentage of ownership in generating station		7.00%
Tucson to Nogales [Member]
Commitments And Contingencies [Line Items]
Transmission line from Tucson to Nogales		60
Transmission Line, in KV		345
TUCSON ELECTRIC POWER COMPANY
Commitments And Contingencies [Line Items]
TEP's share of reclamation costs at expiration dates of the coal supply agreements		$ 44
TEP's recorded obligations for final mine reclamation costs	16	18
TUCSON ELECTRIC POWER COMPANY \| Four Corner [Member]
Commitments And Contingencies [Line Items]
TEP accrued an estimated loss related to Four Corners Generating Station		1
TUCSON ELECTRIC POWER COMPANY \| Tucson to Nogales [Member]
Commitments And Contingencies [Line Items]
Asset Impairment Charges	5
Regulatory Assets		5
Surface Mine Possible Additional Royalty Assessment, Coal Supplier [Member] \| TUCSON ELECTRIC POWER COMPANY \| San Juan [Member]
Commitments And Contingencies [Line Items]
Estimate of Possible Loss Contingency		5
Tucson Electric Power Company's Share of Surface Mine Possible Additional Royalty Assessment [Member] \| TUCSON ELECTRIC POWER COMPANY \| San Juan [Member]
Commitments And Contingencies [Line Items]
Estimate of Possible Loss Contingency		1
Assessment for Coal Severance Tax, Coal Supplier [Member] \| TUCSON ELECTRIC POWER COMPANY \| Four Corner [Member]
Commitments And Contingencies [Line Items]
Estimate of Possible Loss Contingency		30
Tucson Electric Power Company's Share of Assessment for Coal Severance Tax [Member] \| TUCSON ELECTRIC POWER COMPANY \| Four Corner [Member]
Commitments And Contingencies [Line Items]
Estimate of Possible Loss Contingency		$ 1