Preferred Stock, Common Stock and Stockholders' Equity - Common Stock - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Nov. 30, 2017
Sale Of Stock [Line Items]
Common stock, shares outstanding		26,621,954	24,431,914
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		26,621,954	24,431,914
Proceeds from issuance of common stock from ATM, net		$ 3,595,713	$ 6,106,922
FBR Sales Agreement [Member]
Sale Of Stock [Line Items]
Common stock, shares issued		1,490,813	7,004,381
Proceeds from issuance of common stock from ATM, net		$ 3,600,000	$ 6,100,000
Common stock , weighted average price per share		$ 2.46	$ 0.89
FBR Sales Agreement [Member] | Maximum [Member]
Sale Of Stock [Line Items]
Proceeds from issuance of common stock from ATM, net		$ 30,000,000
Common stock, value of shares issuable				$ 16,000,000
Subsequent Event [Member] | Public Offering [Member]
Sale Of Stock [Line Items]
Common stock, shares issued	5,750,000
Shares issued, price per share	$ 2.50
Proceeds from issuance of common stock from ATM, net	$ 14,400,000
Proceeds from issuance of common stock net of underwriting discounts and commissions and offering expenses	$ 13,100,000