Discontinued Operations Discontinued Operations (Details) (Discontinued Operations [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2012
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Revenue	$ 16	$ 38
Operation and Maintenance	6	16
Depreciation, Depletion and Amortization	6	17
Taxes, Other	1	2
Operating Income (Loss)	3	3
Other (Income) and Deductions	(1)	(4)
Taxes other than Income	1	(1)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ 1	$ 0

Tax effect allocated to a disposal group that is classified as a component of the entity reported as a separate component of income before extraordinary items. Includes the tax effects of the following: income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b),(c)

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-Name Accounting Standards Codification

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-Section 50

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Amount of depreciation and amortization attributable to disposal group.

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Amount of operating expenses attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of operating income or loss attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of sales or other form of revenues attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of income (loss) from a disposal group, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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-Topic 810

-SubTopic 10

-Section 45

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The net amount of other income and expense amounts, the components of which are not separately disclosed on the income statement, resulting from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business) also known as other nonoperating income (expense) recognized for the period. Such amounts may include: (a) dividends, (b) interest on securities, (c) net gains or losses on securities, (d) unusual costs, (e) gains or losses on foreign exchange transactions, and (f) miscellaneous other income and expense items.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5

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Taxes, excluding payroll, income and excise taxes, if not included elsewhere, that could include production, real and personal property, and other selling and distribution-related taxes.

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