Stockholders' Equity - Stock Option Activity (Detail) (USD $)	6 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning balance	2,334,326
Number of Shares, Granted	1,565,500	0
Number of Shares, Exercised	(4,166)
Number of Shares, Cancelled	(184,939)
Number of Shares, Ending balance	3,710,721	2,708,063	2,334,326
Weighted Average Exercise Price Per Share, Beginning balance	$ 4.11
Weighted Average Exercise Price Per Share, Granted	$ 2.74
Weighted Average Exercise Price Per Share, Exercised	$ 2.34
Weighted Average Exercise Price Per Share, Cancelled	$ 4.66
Weighted Average Exercise Price Per Share, Ending balance	$ 3.51	$ 4.19	$ 4.11
Weighted Average Remaining Contractual Term (in Years)	7 years 29 days	6 years 9 months 18 days	5 years 5 months 16 days