LEASES - Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets and Liabilities, Lessee [Abstract]
Operating Lease - ROU	$ 6,189	$ 5,838
Finance Leases - ROU	2,519	2,572
Total right-of-use assets	8,708	8,410
Operating leases liabilities - current	2,121	2,178
Finance leases liabilities - current	161	159
Total lease liabilities, current	2,282	2,337
Operating leases liabilities - non-current	3,992	3,607
Finance leases liabilities - non-current	2,431	2,472
Total lease liabilities, non-current	$ 6,423	$ 6,079