Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Assets:
Available-for-sale securities	$ 2,670	$ 6,135
Fair Value, Measurements, Recurring
Assets:
Cash equivalents	45	143
Available-for-sale securities	2,670	6,135
Foreign exchange contracts	4	5
Total Assets	2,719	12,102
Liabilities:
Contingent consideration		500
Foreign exchange contracts	146	96
Total Liabilities	146	596
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	42	98
Total Assets	42	98
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	3	45
Available-for-sale securities	2,670	6,135
Foreign exchange contracts	4	5
Total Assets	2,677	6,185
Liabilities:
Foreign exchange contracts	146	96
Total Liabilities	$ 146	96
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Total Assets		5,819
Liabilities:
Contingent consideration		500
Total Liabilities		500
Convertible Debt Securities | Fair Value, Measurements, Recurring
Assets:
Convertible debt securities		5,774
Convertible Debt Securities | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Convertible debt securities		5,774
Warrants | Fair Value, Measurements, Recurring
Assets:
Stock warrant		45
Warrants | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Stock warrant		$ 45