Short-term Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Sep. 30, 2015
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 14,894	$ 18,114
Short-term Investments, Unrealized Gains	4	3
Short-term Investments, Unrealized Losses		(5)
Short-term investments	14,898	18,112
Corporate bonds
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	10,692	15,166
Short-term Investments, Unrealized Gains	2
Short-term Investments, Unrealized Losses		(5)
Short-term investments	10,694	15,161
Government bonds
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	4,202	2,948
Short-term Investments, Unrealized Gains	2	3
Short-term investments	$ 4,204	$ 2,951