Stockholders' Equity - Common Stock - Additional Information (Detail) - USD ($)		1 Months Ended	2 Months Ended	3 Months Ended
	Mar. 31, 2018	May 08, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Nov. 30, 2017
Sale Of Stock [Line Items]
Proceeds from issuance of common stock, net				$ 544,643	$ 7,334,739
Common stock, shares issued	15,682,480			15,682,480		15,413,610
Underwritten Public Offering [Member]
Sale Of Stock [Line Items]
Common stock shares issues			2,775,861
Purchase price of common stock			$ 2.90		$ 2.90
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]
Proceeds from issuance of common stock, net	$ 545,000
Common stock, shares issued	268,870			268,870
Common stock , weighted average price per share	$ 2.10			$ 2.10
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			$ 75,000,000
FBR Sales Agreement [Member] | Subsequent Event [Member]
Sale Of Stock [Line Items]
Proceeds from issuance of common stock, net		$ 2,500,000
Common stock , weighted average price per share		$ 2.38
Additional common stock, shares issued		1,092,337
Entity public float		$ 43,000,000
Entity public float, common stock shares		15,808,204
Common stock, closing price		$ 2.72
Proceeds from issuance of additional common stock		$ 11,200,000