LEASES - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finance lease expense:
Amortization of right-of-use assets	$ 42	$ 81
Interest on lease liabilities	0	2
Operating lease expense	6,005	6,510
Short-term lease expense	1,571	918
Variable lease expense	678	199
Total lease expense	$ 8,296	$ 7,710