Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Additional Information (Details)

v3.20.2
Common Stock - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 3 Months Ended 9 Months Ended
Oct. 23, 2019
May 31, 2018
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Aug. 31, 2020
Jan. 01, 2020
Dec. 31, 2019
Oct. 30, 2019
Jan. 31, 2019
Dec. 31, 2018
Class Of Stock [Line Items]                        
Common stock, authorized shares     150,000,000   150,000,000       150,000,000   29,000,000 21,147,115
Conversion of non-voting common stock to voting common stock             1,733,904          
Common stock shares modified   2,904,000                    
Fair value of common stock shares modified   $ 0.74                    
Total compensation cost of common stock shares modified   $ 2,126                    
Unrecognized compensation cost, period for recognition   3 years     2 years 9 months 18 days              
Unrecognized compensation cost related to unvested stock-based awards     $ 10,831   $ 10,831              
2019 Plan                        
Class Of Stock [Line Items]                        
Shares reserved for issuance 2,342,288             961,361        
Increase in share reserved percentage 4.00%                      
Share-based compensation, number of shares available for grant     2,329,903   2,329,903              
2019 ESPP                        
Class Of Stock [Line Items]                        
Shares reserved for issuance 234,229                      
Minimum | 2019 ESPP                        
Class Of Stock [Line Items]                        
Shares reserved for issuance                     234,229  
Increase in share reserved percentage 1.00%                      
Stock Options                        
Class Of Stock [Line Items]                        
Compensation cost recognized     $ 1,127 $ 569 $ 3,067 $ 1,481            
Stock Options | 2018 Plan                        
Class Of Stock [Line Items]                        
Number of options granted         1,959,411              
Stock Options | 2019 Plan                        
Class Of Stock [Line Items]                        
Number of options granted         797,572              
Weighted average grant-date fair value of stock options granted         $ 8.25 $ 4.77            
Aggregate grant-date fair value of options vested         $ 1,709 $ 276            
Stock Options | Minimum | 2018 Plan                        
Class Of Stock [Line Items]                        
Percentage of exercise price per share of fair market value         100.00%              
Share-based compensation, vesting period         3 years              
Stock Options | Maximum | 2018 Plan                        
Class Of Stock [Line Items]                        
Term of stock options after grant date         10 years              
Share-based compensation, vesting period         4 years              
Performance-Based Shares                        
Class Of Stock [Line Items]                        
Unrecognized compensation cost related to unvested stock-based awards, other than options     176   $ 176              
Founders                        
Class Of Stock [Line Items]                        
Unrecognized compensation cost, period for recognition         7 months 6 days              
Unrecognized compensation cost related to unvested stock-based awards     407   $ 407              
Research and Development | Stock Options                        
Class Of Stock [Line Items]                        
Compensation cost recognized     539 365 1,449 962            
Research and Development | Founders                        
Class Of Stock [Line Items]                        
Compensation cost recognized     124 132 372 396            
General and Administrative Expense | Stock Options                        
Class Of Stock [Line Items]                        
Compensation cost recognized     588 204 1,618 519            
General and Administrative Expense | Founders                        
Class Of Stock [Line Items]                        
Compensation cost recognized     $ 44 $ 44 $ 132 $ 132            
Voting Common Stock                        
Class Of Stock [Line Items]                        
Common stock, authorized shares     143,590,481   143,590,481       143,590,481 143,590,481    
Non-voting Common Stock                        
Class Of Stock [Line Items]                        
Common stock, authorized shares     6,409,519   6,409,519       6,409,519 6,409,519