Fair Value of Financial Instruments - Financial assets and liabilities accounted for at fair value on a recurring basis by level within the fair value hierarchy (Details) - Estimate of Fair Value Measurement - Fair Value, Measurements, Recurring $ in Millions	Sep. 30, 2018 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities, current	$ 1.8
Foreign Currency Exchange Contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities, current	1.8
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities, current	1.8
Level 2 | Foreign Currency Exchange Contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities, current	$ 1.8