REVENUE - Schedule of Components of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 38,380	$ 43,243	$ 118,317	$ 139,749
Service revenue
Disaggregation of Revenue [Line Items]
Revenue	36,290	41,626	111,691	133,672
Reimbursable expenses
Disaggregation of Revenue [Line Items]
Revenue	1,957	1,416	6,158	5,365
Non-controlling interests
Disaggregation of Revenue [Line Items]
Revenue	$ 133	$ 201	$ 468	$ 712