Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended
	Jan. 31, 2016	Dec. 31, 2013	Sep. 30, 2016	Sep. 30, 2015
Class of Stock [Line Items]
Number of warrants			623,605	1,176,105
Weighted Average Exercise Price			$ 2.50	$ 3.67
Number of Warrants, Expired	552,500
Exercise price of expired warrants	$ 5.00
Remaining contractual life of warrants			10 months
Weighted-average grant date fair value, per share			$ 2.29
Options vested during the period			875,003
Unrecognized compensation expense			$ 2,800,000
Unrecognized compensation expense weighted average period			2 years 2 months 12 days
At-the-Market Offering [Member]
Class of Stock [Line Items]
Common stock shares maximum aggregate offering price		$ 19,200,000
Common stock unsold value			$ 17,600,000
Stock issuances, sales agent commission maximum percentage		3.00%	3.00%
Common stock issued			0	0
Agreement transaction costs		$ 153,000
2008 Incentive Plan [Member]
Class of Stock [Line Items]
Number of common stock, authorized for issuance			7,841,255
Shares available for grant			966,741
Options granted with annual vesting			1,105,300
Contractual life of option grants			10 years
2008 Incentive Plan [Member] | Employees [Member]
Class of Stock [Line Items]
Options granted with annual vesting			1,105,300
Ratable annual vesting period of granted options			4 years
General and Administrative Expense [Member]
Class of Stock [Line Items]
Increase in stock-based compensation expense attributable to option modification to extend exercise period of vested stock options, net of non-vested option forfeitures			$ 274,000
Research and Development Expense [Member] | U.K. [Member]
Class of Stock [Line Items]
Decrease in stock-based compensation expense attributable to stock option forfeitures, net of option modification to extend exercise period of vested stock options			$ (35,000)