EQUITY-BASED COMPENSATION EXPENSE - Incentive Units Activity (Details) - Incentive Units shares in Thousands	12 Months Ended
	Dec. 31, 2020 shares
Number of Units
Unvested, beginning balance (in shares)	2,150
Granted (in shares)	853
Vested (in shares)	(1,384)
Cancelled (in shares)	(1,619)
Unvested, ending balance (in shares)	0