LONG-TERM DEBT - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
LONG-TERM DEBT
Interest expense	$ 9,005	$ 10,665	$ 8,655
Amortization of Loan Costs	454	444	495
Amortization of Discount on Convertible Notes	1,379	1,357	1,273
Total Interest Expense	10,838	12,466	10,423
Total Interest Paid	$ 9,716	$ 10,782	$ 8,419