STOCK BASED COMPENSATION - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock compensation	$ 4,793	$ 5,272	$ 15,128	$ 22,154
Share-based payment arrangement, accelerated cost				5,100
Restricted stock units (RSUs)
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock compensation	3,746	4,273	12,108	15,980
Stock options
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock compensation	$ 1,047	$ 999	$ 3,020	$ 6,174