Income Taxes - Valuation Allowance Activity (Details) - SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Deferred Tax Asset, Valuation Allowance [Roll Forward]      
Valuation allowance, beginning balance $ (12,688) $ (7,727) $ (4,286)
Addition in current year (15,725) (4,961) (3,441)
Valuation allowance, ending balance $ (28,413) $ (12,688) $ (7,727)