Stock-Based Compensation - Compensation expense (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Stock-based compensation expense      
Stock-based compensation expense $ 15,783 $ 35,610 $ 33,665
Research and development expenses      
Stock-based compensation expense      
Stock-based compensation expense 6,863 12,338 8,023
General and administrative expenses      
Stock-based compensation expense      
Stock-based compensation expense $ 8,920 $ 23,272 $ 25,642