Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Balance at beginning of period	$ 219.2	$ 194.6	$ 161.0
Increases as a result of tax positions taken during a prior year	29.0	8.3	28.2
Decreases as a result of tax positions taken during a prior year	(16.3)	(1.9)	(6.8)
Settlements with taxing authorities	(1.1)	(34.9)	(0.7)
Lapse of statutes of limitation	(4.1)	(10.6)	(1.1)
Increases as a result of tax positions taken during the current year	11.3	63.7	14.0
Balance at end of period	238.0	219.2	194.6
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would impact effective tax rate	213.5
Income tax penalties and interest accrued	15.3	11.9
Income tax penalties and interest expense	(5.4)	(2.8)
Estimated unrecognized tax benefit decrease, lower bound	25.0
Estimated unrecognized tax benefit decrease, upper bound	$ 35.0
Foreign Tax Authority
Income Tax Contingency [Line Items]
Income Tax Examination, Year under Examination	2006
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Year under Examination	2009
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Year under Examination	2004
Minimum [Member] | Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Year under Examination		2002
Maximum [Member] | Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Year under Examination		2006