Accrued Liabilities - Schedule of Accrued Compensation and Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued compensation:
Accrued bonuses	$ 9,670	$ 11,582
Accrued payroll	5,543	1,660
Accrued paid time off	4,981	2,441
Other accrued compensation	24	337
Total accrued compensation	20,218	16,020
Accrued expenses and other current liabilities:
Accrued research and development	4,358	1,197
Accrued property and equipment	3,178	2,892
Accrued professional fees	2,209	1,717
Other accrued current liabilities	3,139	3,660
Total accrued expenses and other current liabilities	$ 12,884	$ 9,466