Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued Expenses.
Accrued payroll and related employee expenses	$ 8,018	$ 4,938
Accrued employee performance bonus	7,194	4,873
Employer payroll tax, including social security deferral	3,171	3,034
Accrued rebates	1,510	1,178
Sales tax liability	1,228	1,696
Accrued interest	1,197	4,145
Operating and financing lease liability (current portion)	3,549	4,407
Income taxes payable	2,015
Other	4,215	3,878
Total accrued expenses	$ 32,097	$ 28,149