STOCK-BASED COMPENSATION PLANS - Summary of stock option activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Summary of stock option activity under the option Plan
Weighted Average Remaining Contractual Life, Exercisable (Years)	4 years 1 month 24 days
Employee Stock Option [Member]
Summary of stock option activity under the option Plan
Outstanding at beginning	1,885	2,142
Number of Shares, Granted	653	215
Number of Shares, Expired	(6)
Number of Shares, Forfeited	(174)	(115)
Number of Warrants, Exercised	(503)	(357)
Outstanding at ending	1,855	1,885
Number of Shares, Exercisable	965
Weighted Average Exercise Price, Outstanding Beginning	$ 0.80	$ 0.56
Weighted Average Exercise Price, Granted	5.81	2.99
Weighted Average Exercise Price, Expired	1.00
Weighted Average Exercise Price, Exercised	0.44	0.44
Weighted Average Exercise Price, Forfeited	2.64	1.48
Weighted Average Exercise Price, Outstanding Ending	2.48	$ 0.80
Weighted Average Exercise Price, Exercisable	$ 0.60
Weighted Average Remaining Contractual Life, Outstanding	6 years 5 months 1 day	6 years 3 months 26 days
Weighted Average Remaining Contractual Life, Exercisable (Years)	4 years 1 month 24 days
Aggregate Intrinsic Value, Outstanding	$ 10,032	$ 4,085
Aggregate Intrinsic Value, Exercisable	$ 7,022

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Balance Type:	na
Period Type:	instant

- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.