COMMITMENTS AND CONTINGENCIES - Leases expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating lease, weighted average remaining lease term	1 year 7 months 6 days
Operating lease costs	$ 223	$ 190
Variable lease costs	66	60
Total lease costs	$ 289	$ 250
Minimum
Operating lease liability (in percent)	3.99%
Maximum
Operating lease liability (in percent)	8.95%