STOCK-BASED COMPENSATION - Stock option activity (Details) - USD ($) shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Option Shares
Proceeds from stock option exercised	$ 336	$ 449
Options [Member]
Option Shares
Outstanding at the beginning of the period (in shares)	756	757
Granted (in shares)	84	7
Exercised (in shares)	(5)	(8)
Forfeited (in shares)	(58)	(13)
Outstanding at the end of the period (in shares)	777	743
Inducement Grants [Member]
Option Shares
Outstanding at the beginning of the period (in shares)	180
Granted (in shares)	61
Outstanding at the end of the period (in shares)	241