INCOME TAXES - Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of the changes in unrecognized tax benefits
Balance at beginning of year	$ 13,960	$ 11,008	$ 9,716
Additions for tax positions taken during current year	1,890	2,952	1,292
Balance at end of year	$ 15,850	$ 13,960	$ 11,008