6. Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Payroll and incentive compensation	$ 1,825	$ 1,366
Real estate tax	271	341
Current portion of operating lease liabilities	174	179
Other	317	310
Total accrued expenses	$ 2,587	$ 2,196