Stock Options and Employee Stock Purchase Plan - Summary of Status of Company's Non-Vested Shares (Detail) - $ / shares	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Outstanding Beginning Balance	1,240,941	997,045
Shares, Granted	317,619	341,260
Options, Forfeited	(98,034)	(59,221)
Options, Outstanding Ending Balance	1,449,409	1,240,941
Weighted-Average Grant Date Fair Value, Granted	$ 3.18	$ 3.41
Non-Vested Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Outstanding Beginning Balance	539,519
Shares, Granted	317,619
Shares, Vested	(268,217)
Options, Forfeited	(25,289)
Options, Outstanding Ending Balance	563,632	539,519
Weighted-Average Grant Date Fair Value, Non-vested Beginning Balance	$ 3.29
Weighted-Average Grant Date Fair Value, Granted	3.18
Weighted-Average Grant Date Fair Value, Vested	2.70
Weighted-Average Grant Date Fair Value, Forfeited	1.94
Weighted-Average Grant Date Fair Value, Non-vested Ending Balance	$ 3.35	$ 3.29