STOCK-BASED AWARDS - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 3,268	$ 3,985
Cost of Sales [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	53	47
Selling and Marketing Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	389	441
Technology [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	915	1,227
General and Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 1,911	$ 2,270