DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Allowance of Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Allowance for Doubtful Accounts Receivable
Balance at beginning of year	$ 369	$ 575
Provision for doubtful accounts	535	(145)
Uncollectible accounts written off, net of recovery	(287)	(61)
Balance at end of year	$ 617	$ 369