Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accrued Expenses
Accrued external research and development expense	$ 13,954	$ 8,428
Accrued payroll and related expenses	6,578	7,147
Accrued professional and consulting expense	1,378	1,421
Accrued other	731	460
Accrued restructuring expense	225
Accrued expenses	$ 22,866	$ 17,456