INCOME TAXES - Reconciliation of Income Tax Uncertainties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the beginning and ending amount of income tax uncertainties
Balance at the beginning of period	$ 3,647	$ 3,559	$ 3,080
Increases based on tax positions for the current year	212	412	360
Increases based on tax positions of prior years	790	663	610
Settlements	0	(558)	(491)
Lapse of statute of limitations	(145)	(429)	0
Balance at the end of period	$ 4,504	$ 3,647	$ 3,559