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Warrants - Additional Information (Detail)
 1 Months Ended 3 Months Ended 12 Months Ended
Jul. 31, 2020
USD ($)
$ / shares
shares
May 31, 2020
USD ($)
$ / shares
shares
Sep. 30, 2020
USD ($)
Jun. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
Class Of Warrant Or Right [Line Items]            
Gross proceeds from warrants exercise         $ 9,372,000 $ 5,269,000
July 2020 Warrant Exercise Transaction [Member]            
Class Of Warrant Or Right [Line Items]            
Gain (loss) on extinguishment of warrant liability     $ (682,000)      
July 2020 Warrant Exercise Transaction [Member] | Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants issued, exercise price | $ / shares $ 3.85          
Warrant issued, shares of common stock called by warrant | shares 641,416          
Warrant, exercisable term 5 years 6 months          
Value of warrants $ 2,100,000          
July 2020 Warrant Exercise Transaction [Member] | Warrants [Member] | Expected Volatility [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants and rights outstanding, measurement input 126          
July 2020 Warrant Exercise Transaction [Member] | Warrants [Member] | Stock Price [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants and rights outstanding, measurement input 3.73          
July 2020 Warrant Exercise Transaction [Member] | Warrants [Member] | Risk-Free Interest Rate [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants and rights outstanding, measurement input 0.35          
May 2020 Warrant Exercise Transaction [Member]            
Class Of Warrant Or Right [Line Items]            
Gain (loss) on extinguishment of warrant liability       $ 47,000    
May 2020 Warrant Exercise Transaction [Member] | Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants issued, exercise price | $ / shares   $ 4.775        
Warrant issued, shares of common stock called by warrant | shares   1,392,345        
Warrant, exercisable term   5 years        
Value of warrants   $ 4,400,000        
May 2020 Warrant Exercise Transaction [Member] | Warrants [Member] | Expected Volatility [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants and rights outstanding, measurement input   128        
May 2020 Warrant Exercise Transaction [Member] | Warrants [Member] | Stock Price [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants and rights outstanding, measurement input   3.81        
May 2020 Warrant Exercise Transaction [Member] | Warrants [Member] | Risk-Free Interest Rate [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants and rights outstanding, measurement input   0.38        
March 2018 Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Investors exercised warrants and purchase shares of common stock | shares         641,416  
Warrants issued, exercise price | $ / shares         $ 10.73  
March 2018 Warrants [Member] | July 2020 Warrant Exercise Transaction [Member] | Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Investors exercised warrants and purchase shares of common stock | shares 641,416          
Warrants issued, exercise price | $ / shares $ 3.975          
Gross proceeds from warrants exercise $ 2,600,000          
June 2018 Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Investors exercised warrants and purchase shares of common stock | shares         1,392,345  
Warrants issued, exercise price | $ / shares         $ 9.94  
June 2018 Warrants [Member] | May 2020 Warrant Exercise Transaction [Member] | Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Investors exercised warrants and purchase shares of common stock | shares   1,392,345        
Warrants issued, exercise price | $ / shares   $ 4.90        
Gross proceeds from warrants exercise   $ 6,800,000        
Placement Agent [Member] | July 2020 Warrant Exercise Transaction [Member] | Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants issued, exercise price | $ / shares $ 4.969          
Warrant issued, shares of common stock called by warrant | shares 32,071          
Warrant, exercisable term 5 years 6 months          
Value of warrants $ 101,000          
Placement Agent [Member] | May 2020 Warrant Exercise Transaction [Member] | Warrants [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants issued, exercise price | $ / shares   $ 6.125        
Warrant issued, shares of common stock called by warrant | shares   69,617        
Warrant, exercisable term   5 years        
Value of warrants   $ 215,000