Derivatives - Schedule of Fair Values of Derivative Instruments (Details) - Forward currency forward contracts - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 100
Liability Derivatives		$ 100
Prepaid expenses and other | Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	4,952	2,024
Prepaid expenses and other | Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	159	35
Other accrued liabilities | Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Liability Derivatives	0	0
Other accrued liabilities | Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 65	$ 118