Quarterly report pursuant to Section 13 or 15(d)

Nature of Business - Additional Information (Details)

v3.21.2
Nature of Business - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Jan. 22, 2021
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Class Of Stock [Line Items]                
Gross proceeds from common stock         $ 11,896      
Net Loss   $ 26,027 $ 19,486 $ 62,745 $ 53,908 $ 84,000 $ 75,400 $ 62,300
Accumulated deficit   (439,766)   (439,766)   $ (377,021)    
Cash, cash equivalents and marketable securities   $ 166,706   $ 166,706        
Underwritten Public Offering                
Class Of Stock [Line Items]                
Shares issued 5,400,000              
Public offering price per share $ 14.00              
Gross proceeds from common stock $ 75,600              
Underwriting discounts and commissions and other transaction expenses $ 5,100