Income Taxes (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at beginning of period	$ 143.9us-gaap_UnrecognizedTaxBenefits	$ 122.8us-gaap_UnrecognizedTaxBenefits	$ 119.6us-gaap_UnrecognizedTaxBenefits
Additions for current year tax positions	12.0	6.3	17.4
Additions for prior year tax positions	0	63.8	31.9
Reductions for settlements with tax authorities	(111.4)	0	(46.1)
Reductions for expirations of statutes of limitations	0	(49.0)	0
Balance at end of period	$ 44.5us-gaap_UnrecognizedTaxBenefits	$ 143.9us-gaap_UnrecognizedTaxBenefits	$ 122.8us-gaap_UnrecognizedTaxBenefits

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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