Derivative Financial Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 34.4	$ 25.1
Derivative Liabilities	34.1	25.4
Foreign exchange contracts | Derivatives designated as hedging instruments | Other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	1.8	0.5
Foreign exchange contracts | Derivatives designated as hedging instruments | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0.7	0.5
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0.4	0.4
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1.2	0.7
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	32.2	24.2
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 32.2	$ 24.2