Short-term Investments (Tables)

12 Months Ended

Sep. 30, 2017

Investments Debt And Equity Securities [Abstract]

Short-term Investments

At September 30, 2017, 2016 and 2015, the Company’s short-term investments were composed of the following (in thousands):

	AS OF SEPTEMBER 30, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Short-term investments
Corporate bonds	$	22,829	$	—	$	(31	)	$	22,798
Government bonds		13,363		—		(24	)		13,339
Total	$	36,192	$	—	$	(55	)	$	36,137

	AS OF SEPTEMBER 30, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Short-term investments
Corporate bonds	$	17,342	$	—	$	(19	)	$	17,323
Government bonds		10,169		—		(1	)		10,168
Total	$	27,511	$	—	$	(20	)	$	27,491
	AS OF SEPTEMBER 30, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Short-term investments
Corporate bonds	$	15,166	$	—	$	(5	)	$	15,161
Government bonds		2,948		3		—			2,951
Total	$	18,114	$	3	$	(5	)	$	18,112