Stock Options and Employee Stock Purchase Plan - Summary of Status of Company's Non-Vested Shares (Detail) - $ / shares	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding Beginning Balance (in shares)	1,449,409	1,240,941
Shares, Granted (in shares)	243,881	317,619
Options, Forfeited (in shares)	(87,500)	(98,034)
Options, Outstanding Ending Balance (in shares)	1,602,822	1,449,409
Weighted-Average Grant Date Fair Value, Granted (usd per share)	$ 2.62	$ 3.18
Non-Vested Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding Beginning Balance (in shares)	563,632
Shares, Granted (in shares)	243,881
Shares, Vested	(253,304)
Options, Forfeited (in shares)	(14,224)
Options, Outstanding Ending Balance (in shares)	539,985	563,632
Weighted-Average Grant Date Fair Value, Non-vested Beginning Balance	$ 4.46
Weighted-Average Grant Date Fair Value, Granted (usd per share)	2.72
Weighted-Average Grant Date Fair Value, Vested	3.45
Weighted-Average Grant Date Fair Value, Forfeited	3.34
Weighted-Average Grant Date Fair Value, Non-vested Ending Balance	$ 3.21	$ 4.46