NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2024 USD ($) institution	Sep. 30, 2023 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of financial services organizations, leading marketplace and financial technology brands (more than) | institution		7,900
Spanish Government Agencies | HooYu
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt interest rate (as a percent)	0.00%
Amount outstanding under loan agreement		$ 2.1	$ 1.3
Spanish Government Agencies | HooYu | Other current liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Current loans payable		0.2	0.2
Spanish Government Agencies | HooYu | Other non-current liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Noncurrent loans payable		$ 2.0	$ 1.1
Spanish Government Agencies | Minimum | HooYu
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of loan agreement (in years)	5 years
Spanish Government Agencies | Maximum | HooYu
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of loan agreement (in years)	12 years