Income Taxes - Components of Company's Deferred Tax Asset (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Deferred Tax Assets, Net of Valuation Allowance [Abstract]    
Accrued bonuses $ 63 $ 53
Accrued vacation 26 24
Net operating loss (NOL) carryover 14,975 12,876
Research & development tax credits 3,353 2,902
Share based expense 572 472
Other 4 4
Right of use lease liability 49 69
Fixed asset depreciation 43 55
Total deferred tax asset 19,085 16,455
Less: valuation allowance (19,042) (16,395)
Net deferred tax asset 43 60
Right of use asset (43) (60)
Net deferred tax asset $ 0 $ 0