Derivative Financial Instruments Derivative Financial Instruments (Gross Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Derivative [Line Items]
Forward contracts	$ 827	$ 1,163
Forward contracts	4,837	4,347
Not Designated as Hedging Instrument \| Forward Contracts
Derivative [Line Items]
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	531	623
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	1,718	1,995
Designated as Hedging Instrument \| Forward Contracts
Derivative [Line Items]
Foreign Currency Cash Flow Hedge Asset at Fair Value	296	540
Foreign Currency Cash Flow Hedge Liability at Fair Value	3,119	2,352
Other Current Assets [Member] \| Forward Contracts
Derivative [Line Items]
Forward contracts	827	1,128
Other Noncurrent Assets \| Forward Contracts
Derivative [Line Items]
Forward contracts	0	35
Other Current Liabilities [Member] \| Forward Contracts
Derivative [Line Items]
Forward contracts	4,837	4,329
Other Noncurrent Liabilities [Member] \| Forward Contracts
Derivative [Line Items]
Forward contracts	$ 0	$ 18

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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