Stockholders' Equity - Additional Information (Detail) - USD ($)						1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	Aug. 03, 2016	Aug. 03, 2016	Jul. 25, 2016	Apr. 27, 2016	Apr. 15, 2016	Feb. 29, 2016	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Nov. 30, 2014
Sale Of Stock [Line Items]
Common stock, shares issued							12,350,360	12,350,360		7,201,774
Proceeds from issuance of common stock, net								$ 358,023	$ 4,626,373
Legal, Accounting and Filing Fees								138,000
Payroll withholdings from employees							$ 99,000	$ 99,000	$ 170,000
Common stock for Employee Stock Purchase Plan								34,067	41,176
Unrecognized compensation costs							$ 2,200,000	$ 2,200,000
Weighted average period								1 year 11 days
Amended and Restated Equity Incentive Plan 2013 [Member]
Sale Of Stock [Line Items]
Increase in number of shares of common stock reserved under the plan				500,000
Aggregate number of shares of common stock reserved under the plan				4,786,425
Award plan expiration year				2026
One-Time Option Exchange Program [Member]
Sale Of Stock [Line Items]
Number of stock options exchanged						703,500
Number of stock options exchanged, outstanding						527,624
Number of stock options exchange percentage						75.00%
Options granted, vesting period						3 years
Replacement stock options exercise price						$ 3.04
Incremental compensation expense during period under option exchange						$ 4,700
Unrecognized compensation costs						$ 141,000
Weighted average period						3 years
July 2016 Financing [Member]
Sale Of Stock [Line Items]
Common stock, shares issued			1,804,512
Purchase price of common stock			$ 2.49375
Aggregate gross proceeds from sale of common stock and warrants			$ 4,500,000
Aggregate net proceeds from sale of common stock and warrants			$ 4,000,000
July Warrants [Member]
Sale Of Stock [Line Items]
Warrants exercisable, stock issued			0.75
Warrant exercise price per share			$ 2.41
Warrants expiration date			Jan. 25, 2022
Unregistered warrants to purchase of common stock			1,353,384
July Wainwright Warrants [Member]
Sale Of Stock [Line Items]
Warrant exercise price per share			$ 3.1172
Warrants expiration date			Jul. 21, 2021
Unregistered warrants to purchase of common stock			90,226
August 2016 Financing [Member]
Sale Of Stock [Line Items]
Common stock, shares issued	3,244,120	3,244,120
Purchase price of common stock	$ 3.0825	$ 3.0825
Aggregate gross proceeds from sale of common stock and warrants	$ 10,000,000
Aggregate net proceeds from sale of common stock and warrants	$ 9,200,000
August Warrants [Member]
Sale Of Stock [Line Items]
Warrants exercisable, stock issued	0.5	0.5
Warrant exercise price per share	$ 3.03	$ 3.03
Warrants expiration date	Feb. 03, 2022
Unregistered warrants to purchase of common stock	1,622,060	1,622,060
August Wainwright Warrants [Member]
Sale Of Stock [Line Items]
Warrant exercise price per share	$ 3.853125	$ 3.853125
Warrants expiration date	Jul. 29, 2021
Unregistered warrants to purchase of common stock	162,206	162,206
2016 Financings [Member]
Sale Of Stock [Line Items]
Common stock, shares issued	5,048,632	5,048,632					5,048,632	5,048,632
Aggregate gross proceeds from sale of common stock and warrants		$ 14,500,000					$ 14,500,000
Aggregate net proceeds from sale of common stock and warrants		$ 13,200,000
2016 Financings [Member] | Warrant Liability [Member]
Sale Of Stock [Line Items]
Total initial fair value of warrants issued								$ 4,899,459
MLV Sales Agreement [Member]
Sale Of Stock [Line Items]
Common stock, shares issued							0	0		1,048,507
Common stock, value of shares issuable											$ 6,600,000
Common stock , weighted average price per share										$ 4.78
Proceeds from issuance of common stock, net										$ 4,900,000
FBR Sales Agreement [Member]
Sale Of Stock [Line Items]
Common stock, shares issued							56,000	56,000
Common stock , weighted average price per share							$ 5.45	$ 5.45
Proceeds from issuance of common stock, net								$ 296,000
Common stock, shares issuable					649,074