INDEBTEDNESS - Facility components (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current debt, net of deferred financing costs	$ 15,927	$ 13,243
Non-current debt, net of deferred financing costs and current component	186,063	172,443
Term Loan and DDTL [Member]
Current borrowing on debt	16,355	13,691
Deferred financing costs	(428)	(448)
Current debt, net of deferred financing costs	15,927	13,243
Non-current borrowing on debt	155,057	165,755
Deferred financing costs	(494)	(812)
Non-current debt, net of deferred financing costs and current component	$ 154,563	$ 164,943