Derivative Financial Instruments - Fair Value of Derivatives Included in Balance Sheets (Details) - Cash Flow Hedging - Foreign Currency Forward Contract - Designated as Hedging Instrument - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Assets	$ 0.0	$ 0.0
Liabilities	0.3	0.0
Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Assets	0.0	0.0
Other assets
Derivatives, Fair Value [Line Items]
Assets	0.0	0.0
Other accrued expenses
Derivatives, Fair Value [Line Items]
Liabilities	0.3	0.0
Other non-current liabilities
Derivatives, Fair Value [Line Items]
Liabilities	$ 0.0	$ 0.0