GOODWILL, INTANGIBLE ASSETS, NET, AND DIGITAL ASSETS HELD - Goodwill by segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Goodwill
Balance at beginning of the period	$ 3,140.6	$ 3,122.8
Changes in foreign currency exchange rates	(16.4)	17.8
Adjustments	0.0
Balance at end of the period	3,124.2	3,140.6
Options
Goodwill
Balance at beginning of the period	305.8	305.8
Changes in foreign currency exchange rates	0.0	0.0
Adjustments	0.2
Balance at end of the period	306.0	305.8
North American Equities
Goodwill
Balance at beginning of the period	2,004.4	2,000.8
Changes in foreign currency exchange rates	(12.8)	3.6
Adjustments	(0.8)
Balance at end of the period	1,990.8	2,004.4
Europe and Asia Pacific
Goodwill
Balance at beginning of the period	563.2	549.0
Changes in foreign currency exchange rates	(3.6)	14.2
Adjustments	0.4
Balance at end of the period	560.0	563.2
Global FX
Goodwill
Balance at beginning of the period	267.2	267.2
Changes in foreign currency exchange rates	0.0	0.0
Adjustments	0.2
Balance at end of the period	$ 267.4	$ 267.2