Short-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 18,114	$ 19,900
Short-term Investments, Unrealized Gains	3
Short-term Investments, Unrealized Losses	(5)	(39)
Short-term Investments, Estimated Fair Value	18,112	19,861
Corporate bonds
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	15,166	14,262
Short-term Investments, Unrealized Losses	(5)	(27)
Short-term Investments, Estimated Fair Value	15,161	14,235
Government bonds
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	2,948	5,638
Short-term Investments, Unrealized Gains	3
Short-term Investments, Unrealized Losses		(12)
Short-term Investments, Estimated Fair Value	$ 2,951	$ 5,626