Stock-Based Compensation - Summarize Information about Stock Options (Detail)	12 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, beginning balance | shares	6,691,200
Number of Options Outstanding, Granted | shares	638,000
Number of Options Outstanding, Cancelled | shares	(1,643,927)
Number of Options Outstanding, Exercised | shares	(135,730)
Number of Options Outstanding, ending balance | shares	5,549,543
Number of Options Outstanding, Exercisable | shares	4,065,611
Weighted-Average Exercise Price Per Share, beginning balance | $ / shares	$ 6.56
Weighted-Average Exercise Price Per Share, Granted | $ / shares	1.95
Weighted-Average Exercise Price Per Share, Cancelled | $ / shares	7.02
Weighted-Average Exercise Price Per Share, Exercised | $ / shares	2.01
Weighted-Average Exercise Price Per Share, ending balance | $ / shares	6.00
Weighted-Average Exercise Price Per Share, Exercisable | $ / shares	$ 6.32
Weighted-Average Remaining Contractual Term	6 years 6 months
Weighted-Average Remaining Contractual Term, Exercisable	5 years 9 months 19 days
Aggregate Intrinsic Value | $	$ 3,390,029
Aggregate Intrinsic Value, Exercisable | $	$ 1,872,018