Financial Instruments and Risk Management (Effect of Derivative Instruments on the Condensed Consolidated Balance Sheets Fair Values of Derivative Instruments Derivatives Not Designated As Hedging Instrument) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	$ 91.3	$ 62.2
Fair value of financial instruments	32.3	15.3
Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	7.5	14.0
Fair value of financial instruments	32.3	15.3
Not Designated as Hedging Instruments | Prepaid expenses and other current assets | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	7.5	14.0
Not Designated as Hedging Instruments | Other current liabilities | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	$ 32.3	$ 15.3