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Subsequent Event - Additional Information (Detail) - USD ($)
1 Months Ended 2 Months Ended 3 Months Ended 12 Months Ended
Jan. 29, 2021
Jan. 08, 2021
Jan. 06, 2021
Jan. 01, 2021
Jan. 28, 2021
Mar. 24, 2021
Mar. 24, 2021
Dec. 31, 2020
Dec. 31, 2019
Jul. 04, 2017
Subsequent Event [Line Items]                    
Common stock, par value               $ 0.001 $ 0.001 $ 0.001
Stock issued during period, value               $ 16,897,000    
Common Stock [Member]                    
Subsequent Event [Line Items]                    
Stock issued during period, value               $ 16,000    
Subsequent Event [Member] | Direct Public Offering [Member] | Common Stock [Member]                    
Subsequent Event [Line Items]                    
Net proceeds from common stock shares issued and sold   $ 33,091,000                
Subsequent Event [Member] | 2021 Purchase Agreement [Member] | Direct Public Offering [Member]                    
Subsequent Event [Line Items]                    
Aggregate number of common stock shares issued and sold     32,630,983              
Common stock, par value     $ 0.001              
Gross proceeds from common stock shares issued and sold     $ 35,894,000,000              
Subsequent Event [Member] | 2021 Purchase Agreement [Member] | Direct Public Offering [Member] | Common Stock [Member]                    
Subsequent Event [Line Items]                    
Purchase price per share     $ 1.10              
Offering closed date     Jan. 08, 2021              
Subsequent Event [Member] | ATM Sales Agreement [Member]                    
Subsequent Event [Line Items]                    
Aggregate number of common stock shares issued and sold           5,225,406        
Net proceeds from common stock shares issued and sold           $ 10,594,000        
Subsequent Event [Member] | ATM Sales Agreement [Member] | JonesTrading [Member]                    
Subsequent Event [Line Items]                    
Aggregate number of common stock shares issued and sold         7,174,993          
Net proceeds from common stock shares issued and sold         $ 9,368,000          
Subsequent Event [Member] | ATM Sales Agreement [Member] | Jones Trading Institutional Services LLC and William Blair & Company, LLC [Member] | Maximum [Member]                    
Subsequent Event [Line Items]                    
Stock issued during period, value $ 30,000,000                  
Subsequent Event [Member] | Purchase Agreement [Member] | LPC [Member]                    
Subsequent Event [Line Items]                    
Aggregate number of common stock shares issued and sold             1,375,000      
Gross proceeds from common stock shares issued and sold             $ 2,614,000      
Subsequent Event [Member] | Purchase Agreement [Member] | LPC [Member] | Common Stock [Member]                    
Subsequent Event [Line Items]                    
Net proceeds from common stock shares issued and sold       $ 2,614,000