LEASES - Components of lease expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
LEASES
Amortization of right-of-use assets	$ 4,152	$ 7,442	$ 12,031
Interest on lease liabilities	1,106	1,356	1,993
Operating lease cost	8,359	8,421	8,902
Variable lease cost	2,054	2,205	2,392
Total lease cost	$ 15,671	$ 19,424	$ 25,318