Financial Instruments and Risk Management (Effect of Derivative Instruments on the Condensed Consolidated Balance Sheets Fair Value of Derivative Instruments Derivatives Designated As Hedging Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	$ 40.1	$ 33.8
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	23.3	3.6
Fair value of financial instruments	0.0	12.1
Designated as Hedging Instrument | Prepaid expenses and other current assets | Interest rate swaps
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	11.1	3.6
Designated as Hedging Instrument | Prepaid expenses and other current assets | Foreign exchange forward contracts
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	12.2	0.0
Designated as Hedging Instrument | Prepaid expenses and other current assets | Foreign exchange forward contracts
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	$ 0.0	$ 12.1