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	Jun. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	$ 19.1	$ 43.3
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	0.0	34.8
Fair value of financial instruments	20.0	0.0
Designated as Hedging Instrument | Prepaid expenses and other current assets | Interest rate swaps
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	0.0	22.3
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	12.5
Designated as Hedging Instrument | Prepaid expenses and other current assets | Foreign exchange forward contracts
Derivatives, Fair Value [Line Items]
Fair value of financial instruments	$ 20.0	$ 0.0