INCOME TAXES - Reconciliation of Unrecognized Tax Benefits, excluding Interest and Penalties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits
Unrecognized tax benefits, beginning of period	$ 33,938	$ 31,515	$ 31,806
Additions based on tax positions related to the current year	3,172	2,212	0
Additions for tax positions of prior years	1,568	2,148	1,662
Reductions for tax positions of prior years	(124)	0	(263)
Lapse in statute of limitations	(2,276)	(1,703)	(1,394)
Settlements	(62)	(234)	(296)
Unrecognized tax benefits, end of the period	$ 36,216	$ 33,938	$ 31,515