Dispositions (Income Statement Data) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposals of discontinued operations	$ 1	$ 0
Income tax (credit) expense	(11)	0
Disposals of discontinued operations, net of tax	12	0
Discontinued operations net of tax	$ 12	$ 0
Discontinued operations, net of tax per basic share (in dollars per share)	$ 0.02	$ 0.00
Discontinued operations, net of tax per diluted share (in dollars per share)	$ 0.02	$ 0.00

Amount of gain (loss), before tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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- Definition

Amount of tax expense or benefit on gain (loss), not previously recognized, resulting from the sale of a business component.

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- Definition

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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- Definition

The amount of net income (loss) derived from discontinued operations during the period, net of related tax effect, per each share of common stock or unit outstanding during the reporting period.

+ References

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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+ Details

- Definition

The amount of net income or loss derived from discontinued operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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