Stock-Based Compensation - Summarize Information about Stock Options (Detail)	12 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, beginning balance | shares	5,435,640
Number of Options Outstanding, Granted | shares	1,402,000
Number of Options Outstanding, Cancelled | shares	(109,253)
Number of Options Outstanding, Exercised | shares	(37,187)
Number of Options Outstanding, ending balance | shares	6,691,200
Number of Options Outstanding, Exercisable | shares	3,850,419
Weighted-Average Exercise Price Per Share, beginning balance | $ / shares	$ 6.71
Weighted-Average Exercise Price Per Share, Granted | $ / shares	6.12
Weighted-Average Exercise Price Per Share, Cancelled | $ / shares	9.63
Weighted-Average Exercise Price Per Share, Exercised | $ / shares	3.60
Weighted-Average Exercise Price Per Share, ending balance | $ / shares	6.56
Weighted-Average Exercise Price Per Share, Exercisable | $ / shares	$ 6.22
Weighted-Average Remaining Contractual Term	7 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Exercisable	6 years 6 months
Aggregate Intrinsic Value | $	$ 12,794,064
Aggregate Intrinsic Value, Exercisable | $	$ 9,265,570