Derivative Financial Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 25.1	$ 4.4
Derivative Liabilities	25.4	0.3
Foreign exchange contracts | Derivatives designated as hedging instruments | Other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	0.5	4.0
Foreign exchange contracts | Derivatives designated as hedging instruments | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0.5	0.0
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	0.7	0.3
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Derivative Assets	24.2	0.0
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 24.2	$ 0.0