Commitments Contingencies and Proposed Environmental Matters (Details) (TEP [Member], USD $) In Millions	Sep. 30, 2011
Long term purchase commitments
Long term purchase commitments due within one year	$ 52
Long term purchase commitments due within second year	79
Long term purchase commitments due within third year	50
Long term purchase commitments due within fourth year	39
Long term purchase commitments due within fifth year	16
Long term purchase commitments due After fifth year	204
Long term purchase commitments Total	440
Coal [Member]
Long term purchase commitments
Long term purchase commitments due within one year	34
Long term purchase commitments due within second year	40
Long term purchase commitments due within third year	14
Long term purchase commitments due within fourth year	14
Long term purchase commitments Total	102
Transport [Member]
Long term purchase commitments
Long term purchase commitments due within one year	3
Long term purchase commitments due within second year	4
Long term purchase commitments due within third year	4
Long term purchase commitments due within fourth year	4
Long term purchase commitments due within fifth year	4
Long term purchase commitments due After fifth year	8
Long term purchase commitments Total	27
Purchased Power [Member]
Long term purchase commitments
Long term purchase commitments due within one year	3
Long term purchase commitments due within second year	23
Long term purchase commitments due within third year	20
Long term purchase commitments due within fourth year	21
Long term purchase commitments due within fifth year	12
Long term purchase commitments due After fifth year	196
Long term purchase commitments Total	275
Solar Equipment [Member]
Long term purchase commitments
Long term purchase commitments due within one year	12
Long term purchase commitments due within second year	12
Long term purchase commitments due within third year	12
Long term purchase commitments Total	$ 36

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The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than four and within five years from the balance sheet date.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 47

-Paragraph 7

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

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The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid within one year of the balance sheet date.

+ References

+ Details

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than three and within four years from the balance sheet date.

+ References

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The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than one and within two years from the balance sheet date.

+ References

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The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than two and within three years from the balance sheet date.

+ References

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The amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation as of the balance sheet date.

+ References

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid after five years from the balance sheet date.

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