ACCOUNTS RECEIVABLE - Allowance for doubtful accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
ACCOUNTS RECEIVABLE
Balance at beginning of period	$ 500	$ 199
Provision for uncollectible accounts, net of recoveries	447	377
Uncollectible accounts written off	(282)	(76)
Balance at end of period	$ 665	$ 500