Income Taxes (Details 3) (USD $) In Millions	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Beginning Balance	$ 56.1	$ 40.4	$ 28.4
Additions for tax positions related to prior years	7.4	11.1	7.9
Reductions for tax positions related to prior years	(5.0)	(2.2)
Additions for tax positions related to the current year		12.9	9.2
Reductions for tax positions related to the current year	(1.8)
Reductions attributable to settlements with taxing authorities		(0.2)	(2.1)
Reductions as a result of a lapse of the applicable statute of limitations	(0.3)	(5.9)	(3.0)
Ending Balance	$ 56.4	$ 56.1	$ 40.4

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The gross amount of unrecognized tax benefits (tax reductions recognized in financial reports but excluded from tax returns) pertaining to uncertain tax positions taken in tax returns as of the beginning balance sheet date, excluding amounts pertaining to examined tax returns.

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The gross amount of decreases in unrecognized tax benefits resulting from tax positions that have been or will be taken in the tax return for the current period, excluding amounts pertaining to examined tax returns.

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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 gross amount of decreases in unrecognized tax benefits resulting from settlements with taxing authorities.

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The gross amount of increases in unrecognized tax benefits resulting from tax positions that have been or will be taken in the tax return for the current period, excluding amounts pertaining to examined tax returns.

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The gross amount of increases 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 gross amount of decreases in unrecognized tax benefits resulting from lapses of the applicable statutes of limitations.

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