Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Income Taxes
Income tax provision	$ 184.9	$ 18.9	$ 624.7	$ 104.4
Pre-tax income	550.6	79.3	1,848.5	302.7
Effective income tax rate (as a percent)	33.60%	23.90%
Effective tax rate based on pre-tax income exclusive of earnings attributable to noncontrolling interests (as a percent)	37.10%	33.60%
Valuation allowance	13.1		13.1
Decrease in unrecognized tax benefits			4.4
Unrecognized tax benefits	118.8		118.8
Decrease in portion of unrecognized tax benefits, if recognized, would affect the effective tax rate			5.9
Portion of unrecognized tax benefits, if recognized, would affect the effective tax rate	$ 46.0		$ 46.0

A ratio calculated by dividing the amount of income tax expense on pretax income from continuing operations excluding the portion attributable to noncontrolling interests for the period by GAAP-basis pretax income from continuing operations excluding the portion attributable to noncontrolling interests.

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The amount of increase or decrease in unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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The sum of the portions of deferred tax assets as of the balance sheet date for which, based on the weight of available evidence, it is more likely than not will not be realized through future reductions of tax-based income.

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A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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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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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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The gross amount of decreases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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