ALLOWANCE FOR CREDIT LOSSES - NARRATIVE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Provision for credit losses	$ (20,342)	$ (13,985)	$ (36,745)	$ (23,933)
Allowance for credit losses	35,253	41,055	35,253	41,055	$ 30,875	$ 34,092	$ 27,070	$ 17,122
Transaction-based revenues
Disaggregation of Revenue [Line Items]
Provision for credit losses	19,000	13,400	34,900	23,300
Allowance for credit losses	32,900	40,400	32,900	40,400
Other revenues
Disaggregation of Revenue [Line Items]
Provision for credit losses	1,300	600	1,800	600
Allowance for credit losses	$ 2,400	$ 700	$ 2,400	$ 700