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Common Stock and Warrants - Additional Information (Details)
$ / shares in Units, $ / shares in Units, $ in Millions
 1 Months Ended 6 Months Ended
Jun. 30, 2021
USD ($)
$ / shares
shares
Jun. 30, 2021
CAD ($)
shares
Feb. 01, 2021
USD ($)
$ / shares
shares
Oct. 26, 2020
USD ($)
$ / shares
shares
Mar. 20, 2020
USD ($)
$ / shares
shares
Jan. 27, 2020
USD ($)
Apr. 24, 2018
shares
Apr. 24, 2018
USD ($)
shares
Apr. 13, 2018
USD ($)
$ / shares
shares
Apr. 30, 2021
shares
Mar. 31, 2020
USD ($)
Jun. 30, 2021
USD ($)
$ / shares
shares
Jun. 30, 2020
USD ($)
$ / shares
shares
Dec. 31, 2020
$ / shares
shares
Dec. 31, 2019
USD ($)
Apr. 13, 2018
$ / shares
shares
Schedule Of Stockholders Equity [Line Items]                                
Common stock, shares authorized 150,000,000                     150,000,000   150,000,000    
Common stock, par value | $ / shares $ 0.001                     $ 0.001   $ 0.001    
Preferred stock, shares authorized 10,000,000                     10,000,000   10,000,000    
Preferred stock, par value | $ / shares $ 0.001                     $ 0.001   $ 0.001    
Common share, voting rights                       one vote per share        
Common share, dividends declared | $                       $ 0        
Gross proceeds from issuance of common stock | $                       11,037,000 $ 7,233,000      
Warrants liability | $ $ 0                     0 $ 1,000   $ 5,000  
Warrants Outstanding | $ $ 0                     $ 0        
April 2018 Offering                                
Schedule Of Stockholders Equity [Line Items]                                
Warrants to purchase number of common stock, shares                 61,197             61,197
Price per share | $ / shares                 $ 261.45              
Net proceeds from offering | $               $ 16,300,000                
Fair value of warrants at issuance | $                 $ 7,400,000              
Warrant exercisable price per share | $ / shares                               $ 428.75
Warrants expiration date                 Apr. 10, 2021              
Number of common stock converted by each warrant                 1             1
Class of warrants exercised 2,025 2,025                            
Proceeds from the exercise of warrants | $   $ 0.9                            
Class of warrants expired                   68,351            
April 2018 Offering | Common Stock                                
Schedule Of Stockholders Equity [Line Items]                                
Shares issued                 61,197              
Over-Allotment Option                                
Schedule Of Stockholders Equity [Line Items]                                
Warrants to purchase number of common stock, shares             9,179 9,179                
Price per share | $ / shares     $ 18.525                          
Over-Allotment Option | Common Stock                                
Schedule Of Stockholders Equity [Line Items]                                
Shares issued     29,797       9,179                  
2020 ATM                                
Schedule Of Stockholders Equity [Line Items]                                
Price per share | $ / shares                         $ 21.68      
Gross proceeds from issuance of common stock | $                         $ 5,000,000.0      
Offering expenses incurred | $                         $ 181,000      
2020 ATM | Form S3 Shelf Registration                                
Schedule Of Stockholders Equity [Line Items]                                
Aggregate offering amount | $           $ 11,340,000         $ 9,150,000          
2020 ATM | Common Stock                                
Schedule Of Stockholders Equity [Line Items]                                
Shares issued                         2      
March 2020 Offering                                
Schedule Of Stockholders Equity [Line Items]                                
Warrants to purchase number of common stock, shares         178,776                      
Price per share | $ / shares         $ 12.25                      
Fair value of warrants at issuance | $         $ 800,000                      
Warrant exercisable price per share | $ / shares         $ 16.10                      
Number of common stock converted by each warrant         1                      
Class of warrants exercised 81,633 81,633                            
Proceeds from the exercise of warrants | $ $ 1,300,000                              
Gross proceeds from issuance of common stock | $         $ 2,200,000                      
Underwriting discounts and commissions paid | $         $ 300,000                      
Warrants expiration date         Mar. 20, 2025                      
March 2020 Offering | Common Stock                                
Schedule Of Stockholders Equity [Line Items]                                
Shares issued         178,776                      
October 2020 Offering                                
Schedule Of Stockholders Equity [Line Items]                                
Shares issued       187,646                        
Warrants to purchase number of common stock, shares       93,817                        
Price per share | $ / shares       $ 18.20                        
Fair value of warrants at issuance | $       $ 600,000                        
Warrant exercisable price per share | $ / shares       $ 15.82                        
Gross proceeds from issuance of common stock | $       $ 3,400,000                        
Share issuance cost including placement agent fees | $       $ 300,000                        
Warrants expiration period       3 years                        
Percentage of right to participate subsequent financing       30.00%                        
October 2020 Offering | Minimum                                
Schedule Of Stockholders Equity [Line Items]                                
Subscription to participate subsequent financing | $       $ 250,000                        
October 2020 Offering | Officer, Affiliates of an Officer and Director                                
Schedule Of Stockholders Equity [Line Items]                                
Price per share | $ / shares       $ 18.354                        
Warrant exercisable price per share | $ / shares       $ 16.1665                        
October 2020 Offering | Placement Agent                                
Schedule Of Stockholders Equity [Line Items]                                
Shares issued       961                        
Price per share | $ / shares       $ 19.775                        
October 2020 Offering | Common Stock                                
Schedule Of Stockholders Equity [Line Items]                                
Number of common stock converted by each warrant       0.50                        
Common unit issued       1                        
February 2021 Offering                                
Schedule Of Stockholders Equity [Line Items]                                
Warrants to purchase number of common stock, shares     372,468                          
Price per share | $ / shares     $ 14.82                          
Net proceeds from offering | $     $ 9,600,000                          
Fair value of warrants at issuance | $     $ 2,600,000                          
Warrant exercisable price per share | $ / shares     $ 16.302                          
Number of common stock converted by each warrant     0.50                          
Class of warrants exercised 262 262                            
Proceeds from the exercise of warrants | $ $ 4,000                              
Warrants expiration period     5 years                          
February 2021 Offering | Common Stock                                
Schedule Of Stockholders Equity [Line Items]                                
Shares issued     744,936                          
Class A Common Stock                                
Schedule Of Stockholders Equity [Line Items]                                
Common stock, shares authorized 150,000,000                     150,000,000        
Common stock, par value | $ / shares $ 0.001                     $ 0.001