Derivative Instruments and Hedging Activities - Balance Sheet Location (Details) - Foreign currency forward contracts - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Designated derivatives: | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 3.4	$ 4.1
Designated derivatives: | Accrued liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	2.2	1.4
Non-designated derivatives: | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	1.6	2.2
Non-designated derivatives: | Accrued liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 1.6	$ 2.4