Income Taxes - Additional Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013 Subsidiary	Mar. 31, 2012
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ 27	$ 37
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%	35.00%
Income Tax Reconciliation, Repatriation of Foreign Earnings	2	2
Number of Purchased Noncontrolling Interests in Foreign Subsidiaries, Related to Release of Valuation Allowance Against Deferred Tax Assets	3
Group Three
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance	800
United Kingdom \| Valuation Allowance
Income Taxes [Line Items]
Change in Deferred Tax Assets Valuation Allowance	$ 2

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

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- Definition

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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- Definition

The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

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