STOCK-BASED COMPENSATION - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	$ 2,261	$ 1,220
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	9	(32)
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	610	202
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	240	23
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	$ 1,402	$ 1,027