Preferred Stock, Common Stock and Stockholders' Equity - Common Stock - Additional Information (Detail) - USD ($)							2 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2018	Feb. 16, 2017	Dec. 15, 2016	Aug. 03, 2016	Jul. 25, 2016	Apr. 15, 2016	Mar. 31, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2017
Sale Of Stock [Line Items]
Common stock, shares outstanding									15,413,610	12,350,360
Shareholders voting power description									Each share of common stock is entitled to one vote. The holders of the common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors of the Company.
Dividends declared on common stock									$ 0
Common stock, shares issued									15,413,610	12,350,360
Weighted average exercise price of warrants									$ 3.46	$ 3.29
Proceeds from issuance of common stock, net									$ 7,389,101	$ 354,855
July 2016 Financing [Member]
Sale Of Stock [Line Items]
Common stock, shares issued					1,804,512
Purchase price of common stock					$ 2.49375
Unregistered warrants to purchase of common stock		526,315							2,449,129
Weighted average exercise price of warrants		$ 2.41
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
Reclassification of warrant liability to Additional Paid-in Capital		$ 1,400,000
Common stock shares issued upon conversion of warrants		211,860
July Warrants [Member]
Sale Of Stock [Line Items]
Warrants exercisable, stock issued					0.75
Unregistered warrants to purchase of common stock					1,353,384
Weighted average exercise price of warrants					$ 2.41
Warrants expiration date					Jan. 25, 2022
July Wainwright Warrants [Member]
Sale Of Stock [Line Items]
Unregistered warrants to purchase of common stock					90,226
Weighted average exercise price of warrants					$ 3.1172
Warrants expiration date					Jul. 21, 2021
August 2016 Financing [Member]
Sale Of Stock [Line Items]
Common stock, shares issued				3,244,120
Purchase price of common stock				$ 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
Unregistered warrants to purchase of common stock				1,622,060
Weighted average exercise price of warrants				$ 3.03
Warrants expiration date				Feb. 03, 2022
August Wainwright Warrants [Member]
Sale Of Stock [Line Items]
Unregistered warrants to purchase of common stock				162,206
Weighted average exercise price of warrants				$ 3.853125
Warrants expiration date				Jul. 29, 2021
2016 Financings [Member]
Sale Of Stock [Line Items]
Common stock, shares issued								5,048,632
Aggregate gross proceeds from sale of common stock and warrants								$ 14,500,000
2016 Financings [Member] | Warrant Liability [Member]
Sale Of Stock [Line Items]
Total initial fair value of warrants issued									$ 4,899,459
Warrant Amendments [Member]
Sale Of Stock [Line Items]
Unregistered warrants to purchase of common stock			252,432
Amendment Date			Dec. 15, 2016
Reclassification of warrant liability to Additional Paid-in Capital			$ 207,000
Underwritten Public Offering [Member]
Sale Of Stock [Line Items]
Purchase price of common stock							$ 2.90
Common stock shares issues							2,775,861
Gross proceeds from public offering of common stock							$ 8,000,000
Proceeds from issuance of common stock, net							$ 7,300,000
FBR Sales Agreement [Member]
Sale Of Stock [Line Items]
Common stock, shares issued										56,000
Proceeds from issuance of common stock, net										$ 296,000
Common stock, shares issuable						649,074
Common stock , weighted average price per share										$ 5.45
FBR Sales Agreement [Member] | Maximum [Member]
Sale Of Stock [Line Items]
Common stock, value of shares issuable											$ 16,000,000
Entity public float									$ 75,000,000
FBR Sales Agreement [Member] | Subsequent Event [Member]
Sale Of Stock [Line Items]
Common stock, shares issued	79,758
Proceeds from issuance of common stock, net	$ 160,000
Common stock , weighted average price per share	$ 2.08
Proceeds from issuance of additional common stock	$ 11,900,000
Entity public float	$ 36,100,000
Entity public float, common stock shares	12,938,176
Common stock, closing price	$ 2.79