Income Taxes - Deferred Income Tax Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Components of Deferred Tax Assets [Abstract]
Net operating loss carryforwards	$ 101,863	$ 83,671
Research and development tax credit carryforwards	5,444	4,616
Capitalized research and development expenses	1,760	2,193
Lease liabilities	1,243	1,440
Other	3,372	2,452
Total deferred tax assets	113,682	94,372
Valuation allowance	(111,835)	(92,197)
Deferred tax assets, net of valuation allowance	1,847	2,175
Right of use assets	1,847	2,175
Total deferred tax liabilities	1,847	2,175
Total deferred tax assets, net	$ 0	$ 0