Income Taxes - Net deferred tax assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 20,054	$ 14,688
Research and development tax credit carryforwards	7,054	6,064
Lease liability	1,483	1,871
Deferred Revenue	2,160	134
Accrued expenses and other	3,194	1,730
Total deferred tax assets	33,945	24,487
Deferred tax liabilities:
Right-of-use asset	(1,314)	(1,602)
Total deferred tax liabilities	(1,314)	(1,602)
Valuation allowance	(32,631)	(22,885)	$ (20,903)
Net deferred tax assets	$ 0	$ 0