ACCOUNTING POLICIES (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) reporting_unit	Dec. 31, 2020 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Non controlling interest in acquisitions (percent)	100.00%
Recognized liabilities acquired (percent)	100.00%
Number of reporting units | reporting_unit	1
Money market fee waiver | $	$ 153.7	$ 40.7
Estimated forfeitures (percent)	3.00%
Percentage of excess in projected benefit obligation and fair value assets to be amortized (percent)	10.00%
Buildings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Useful life of property and equipment	50 years
Minimum
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Reporting period lag between Parent Company and Consolidated Entity	1 month
Intangible assets, useful life, years	2 years
Minimum | Computer and other various equipment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Useful life of property and equipment	3 years
Minimum | Software development
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Useful life of property and equipment	5 years
Maximum
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Reporting period lag between Parent Company and Consolidated Entity	3 months
Sales commissions amortization period	6 years
Intangible assets, useful life, years	12 years
Settlement period for fund and investor receivables	4 days
Maximum | Computer and other various equipment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Useful life of property and equipment	7 years
Maximum | Software development
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Useful life of property and equipment	7 years