Income Taxes - Deferred Income Tax (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets
Net operating loss carryforwards	$ 140,581	$ 121,346
Research and development tax credits	9,149	6,949
Reserves and accruals	4,781	4,984
Operating lease liability	2,615	2,588
Other	6,738	4,702
Total deferred tax assets	163,864	140,569
Less: Valuation allowance	(161,487)	(138,214)
Net deferred tax assets	2,377	2,355
Deferred tax liabilities
Right-of-use assets	(2,377)	(2,355)
Total deferred tax liabilities	(2,377)	(2,355)
Net deferred tax assets	$ 0	$ 0