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Stockholders' Equity - 2019 Equity Financing - Additional Information (Detail) - USD ($)
 1 Months Ended 12 Months Ended
Feb. 25, 2020
Feb. 29, 2020
Apr. 30, 2019
Jan. 31, 2019
Dec. 31, 2019
Share Offering [Member] | Subsequent Event [Member]          
Class of Stock [Line Items]          
Common stock issued 15,000,000        
Gross proceeds from issuance of common stock $ 21,750,000        
Share issuance costs $ 1,750,000        
Price per share $ 1.45        
At-the-Market Offering [Member]          
Class of Stock [Line Items]          
Common stock shares maximum aggregate offering price       $ 20,000,000  
Stock issuances, sales agent commission maximum percentage       3.00%  
Common stock issued         2,998,871
Weighted average common stock price per share         $ 1.50
Gross proceeds from issuance of common stock         $ 4,500,000
Share issuance costs         $ 221,000
2019 Equity Financing [Member] | Share Offering [Member]          
Class of Stock [Line Items]          
Common stock issued     10,526,500    
Gross proceeds from issuance of common stock     $ 20,000,000    
Share issuance costs     $ 1,700,000    
Price per share     $ 1.90    
2019 Equity Financing [Member] | Share Offering [Member] | Subsequent Event [Member]          
Class of Stock [Line Items]          
Common stock issued   15,000,000      
Gross proceeds from issuance of common stock   $ 21,750,000      
Share issuance costs   $ 1,750,000      
Price per share   $ 1.45