INDEBTEDNESS - Credit facility (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current component of term loan, net of deferred financing costs	$ 9,941	$ 3,256
Term loan, net of deferred financing costs and current component	175,808	67,296
Long Term Debt Current [Member]
Borrowing on secured term loan	10,412	3,609
Deferred financing costs	(471)	(353)
Current component of term loan, net of deferred financing costs	9,941	3,256
Long Term Debt Noncurrent [Member]
Borrowing on secured term loan	177,069	68,578
Deferred financing costs	(1,261)	(1,282)
Term loan, net of deferred financing costs and current component	$ 175,808	$ 67,296