Facility Lease - Lease cost (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Operating lease cost      
Operating lease costs $ 1,046 $ 957 $ 960
Costs of non-lease components (previously common area maintenance) 396 351 324
Total operating lease cost 1,442 1,308 1,284
Other Information      
Operating cash flows used for operating lease $ 1,645 $ 1,506 $ 1,449
Remaining lease term 3 years 1 month 6 days 2 years 1 month 6 days 3 years 1 month 6 days
Discount rate 8.00% 10.00% 10.00%