Stock-Based Compensation - Summarize Information about Stock Options (Detail)	6 Months Ended
	Mar. 31, 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	1,380,000
Number of Options Outstanding, Cancelled | shares	(87,182)
Number of Options Outstanding, Exercised | shares	(4,687)
Number of Options Outstanding, ending balance | shares	6,723,771
Number of Options Outstanding, Exercisable | shares	3,250,256
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	8.77
Weighted Average Exercise Price Per Share, Exercised | $ / shares	5.45
Weighted Average Exercise Price Per Share, ending balance | $ / shares	6.57
Weighted Average Exercise Price Per Share, Exercisable | $ / shares	$ 6.15
Weighted Average Remaining Contractual Term	7 years 9 months 18 days
Weighted Average Remaining Contractual Term, Exercisable	6 years 8 months 12 days
Aggregate Intrinsic Value | $	$ 3,002,814
Aggregate Intrinsic Value, Exercisable | $	$ 2,262,299