SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Earn-Out and Holdback Liabilities Reconciliation (Details) - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
44196	$ 20,538	$ 43,175
44561	0	20,538
Earn-Out Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Payments against the earn-out liabilities	(7,500)	(11,867)
Change in fair value of contingent consideration	96	(21,099)
Holdback Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Payments against the earn-out liabilities	$ (13,134)
Change in fair value of contingent consideration		$ 10,329