Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Balance at beginning of period	$ 226.9	$ 238.0	$ 219.2
Increases as a result of tax positions taken during a prior year	65.0	5.2	29.0
Decreases as a result of tax positions taken during a prior year	(47.5)	(19.7)	(16.3)
Settlements with taxing authorities	(4.6)	(4.1)	(1.1)
Lapse of statutes of limitation	(11.8)	(3.8)	(4.1)
Increases as a result of tax positions taken during the current year	18.7	11.3	11.3
Balance at end of period	246.7	226.9	$ 238.0
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would impact effective tax rate	221.0
Income tax penalties and interest accrued	20.9	20.1
Income tax penalties and interest expense	(0.7)	$ (4.8)
Minimum [Member]
Income Tax Contingency [Line Items]
Anticipated decrease in unrecognized tax benefits	25.0
Maximum [Member]
Income Tax Contingency [Line Items]
Anticipated decrease in unrecognized tax benefits	$ 35.0