Purchase Agreement and Offerings - Additional Information (Detail) - USD ($)					12 Months Ended
	Sep. 04, 2019	Aug. 12, 2019	Dec. 28, 2018	Apr. 28, 2017	Dec. 31, 2019	Dec. 11, 2019
Stockholders Equity Common Stock [Line Items]
Total shares of common stock sold (in shares)					3,528,532
Offering price (in dollars per share)				$ 1.00
Net proceeds from public offering				$ 23,200,000
Gross proceeds					$ 25,989,000
Series A Warrant
Stockholders Equity Common Stock [Line Items]
Warrants, exercise price (in dollars per share)				$ 13.00
Series B Warrant
Stockholders Equity Common Stock [Line Items]
Warrants, exercise price (in dollars per share)				$ 13.00		$ 1.39
Stifel, Nicolaus & Company, Incorporated
Stockholders Equity Common Stock [Line Items]
Percentage of commission paid			3.00%
Total shares of common stock sold (in shares)					0
Stifel, Nicolaus & Company, Incorporated | Maximum
Stockholders Equity Common Stock [Line Items]
Sale of common stock			$ 75,000,000.0
Common Stock | Series A
Stockholders Equity Common Stock [Line Items]
Gross proceeds from public offering				$ 24,900,000
Common Stock | Series A Warrant
Stockholders Equity Common Stock [Line Items]
Number of common stock or warrants in each unit				0.077
Common Stock | Series B Warrant
Stockholders Equity Common Stock [Line Items]
Gross proceeds from public offering				$ 24,900,000
Number of common stock or warrants in each unit				0.058
Two Thousand Nineteen Sales Agreement
Stockholders Equity Common Stock [Line Items]
Sale of common stock		$ 25,000,000.0
Percentage of commission paid		3.00%
Total shares of common stock sold (in shares)					1,374,686
Gross proceeds					$ 7,193,000
Underwriting Agreement
Stockholders Equity Common Stock [Line Items]
Gross proceeds					$ 18,796,000
Public Stock Offering | Underwriting Agreement
Stockholders Equity Common Stock [Line Items]
Number of shares issued					2,153,846
Over-Allotment Option | Underwriting Agreement
Stockholders Equity Common Stock [Line Items]
Number of shares issued	323,077