Financial Instruments (Foreign Exchange Risk and Its Classification on Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Designated derivative Instruments
Asset position
Asset position	$ 0.0	$ 0.0
Liability position
Liability position	25.3	7.7
Undesignated derivative instruments
Asset position
Asset position	17.3	17.9
Potential effect of rights to offset, asset position	(6.1)	(2.7)
Net derivative, asset position	11.2	15.2
Liability position
Liability position	44.3	14.2
Potential effect of rights to offset, liability position	(6.1)	(2.7)
Net derivative, liability position	38.2	11.5
Foreign exchange contracts | Prepaid expenses and other current assets | Undesignated derivative instruments
Asset position
Asset position	17.3	17.9
Foreign exchange contracts | Other current liabilities | Undesignated derivative instruments
Liability position
Liability position	19.0	6.5
Interest rate contracts | Long term borrowings | Designated derivative Instruments
Asset position
Asset position	0.0	0.0
Liability position
Liability position	$ 25.3	$ 7.7