Derivative Financial Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 21.6	$ 25.1
Derivative Liabilities	20.0	25.4
Foreign exchange contracts | Derivatives designated as hedging instruments | Other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	4.2	0.5
Foreign exchange contracts | Derivatives designated as hedging instruments | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0.0	0.5
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0.1	0.4
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	2.7	0.7
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	17.3	24.2
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 17.3	$ 24.2