Derivative Instruments - Notional Amounts Outstanding under Foreign Currency Contracts - Fair Value of Assets (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Fair Value of Assets	$ 4	$ 5
Foreign Currency Contract, Buy Japanese Yen, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Fair Value of Assets	1
Foreign Currency Contract, Buy United States Dollar, Sell British Pound, Maturing October 2017
Derivative [Line Items]
Fair Value of Assets	1
Foreign Currency Contract, Buy United States Dollar, Sell Swiss Franc, Maturing October 2017
Derivative [Line Items]
Fair Value of Assets	$ 2
Foreign Currency Contract, Buy British Pound, Sell Swedish Krona, Maturing October 2016
Derivative [Line Items]
Fair Value of Assets		1
Foreign Currency Contract, Buy United States Dollar, Sell British Pound, Maturing October 2016
Derivative [Line Items]
Fair Value of Assets		2
Foreign Currency Contract, Buy Korean Won, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Fair Value of Assets		1
Foreign Currency Contract, Buy United States Dollar, Sell Israeli Shekel, Maturing October 2016
Derivative [Line Items]
Fair Value of Assets		$ 1