STOCK-BASED COMPENSATION PLANS - Summary of stock option activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Summary of stock option activity under the option Plan
Outstanding and Exercisable at June 30, 2020	1,153
Number of Shares, Exercisable	593
Weighted Average Exercise Price, Granted	$ 10.15	$ 4.53
Employee Stock Option [Member]
Summary of stock option activity under the option Plan
Outstanding at December 31, 2019	1,855
Number of Shares, Granted	14
Number of Shares, Forfeited	(206)
Number of Warrants, Exercised	(510)
Outstanding and Exercisable at June 30, 2020	1,153		1,855
Number of Shares, Exercisable	593
Weighted Average Exercise Price, Outstanding at December 31, 2019	$ 2.48
Weighted Average Exercise Price, Granted	10.15
Weighted Average Exercise Price, Forfeited	5.10
Weighted Average Exercise Price, Exercised	0.99
Weighted Average Exercise Price, Outstanding at June 30, 2020	2.77		$ 2.48
Weighted Average Exercise Price, Exercisable at June 30, 2020	$ 0.70
Weighted Average Remaining Contractual Life, Outstanding	6 years 9 months 14 days		6 years 5 months 1 day
Weighted Average Remaining Contractual Life, Exercisable (Years)	5 years 3 months 18 days
Aggregate Intrinsic Value, Outstanding	$ 25,497		$ 10,032
Aggregate Intrinsic Value, Exercisable	$ 14,341