Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Class of Stock [Line Items]
Net proceeds from issuance of stock and warrants	$ 0	$ 6,302,000
Common stock, par value (in dollars per share)	$ 0.0001		$ 0.0001
Compensation cost not yet recognized	$ 314,025
Compensation cost not yet recognized, period for recognition	2 years 4 months 24 days
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)	3,260.7
Shares converted (in shares)	3,739.3
Series F Preferred Stock
Class of Stock [Line Items]
Shares converted (in shares)	(7,927.05)
Common Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion (in shares)	(3,014,087)
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)	14,052.93		14,052.93
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)	3,260.7		7,000
Series F Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)	0		7,927.05
Common Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion (in shares)	(1,421,787)