Short-term Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 27,223	$ 18,114
Short-term Investments, Unrealized Gains	31	3
Short-term Investments, Unrealized Losses		(5)
Short-term Investments, Estimated Fair Value	27,254	18,112
Corporate bonds
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	17,655	15,166
Short-term Investments, Unrealized Gains	17
Short-term Investments, Unrealized Losses		(5)
Short-term Investments, Estimated Fair Value	17,672	15,161
Government bonds
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	9,568	2,948
Short-term Investments, Unrealized Gains	14	3
Short-term Investments, Estimated Fair Value	$ 9,582	$ 2,951