Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accrued Liabilities
Accrued payroll and related employee expenses	$ 4,743	$ 3,954
Accrued employee performance bonus	1,497	3,920
Accrued interest	4,740	4,951
Operating and financing lease liability (current portion)	4,675	4,494
Other	5,318	5,501
Total accrued expenses	$ 20,973	$ 22,820