Stockholders' Equity - Stock Option Activity (Detail) - $ / shares	6 Months Ended	12 Months Ended
	Mar. 31, 2016	Sep. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning balance	3,647,705
Number of Shares, Granted	94,500
Number of Shares, Exercised	(121,939)
Number of Shares, Cancelled	(44,896)
Number of Shares, Ending balance	3,575,370	3,647,705
Weighted Average Exercise Price Per Share, Beginning balance	$ 3.70
Weighted Average Exercise Price Per Share, Granted	4.43
Weighted Average Exercise Price Per Share, Exercised	2.57
Weighted Average Exercise Price Per Share, Cancelled	3.92
Weighted Average Exercise Price Per Share, Ending balance	$ 3.76	$ 3.70
Weighted Average Remaining Contractual Term (in Years)	6 years 8 months 5 days	7 years 1 month 24 days