GOODWILL, INTANGIBLE ASSETS, NET, AND DIGITAL ASSETS HELD - Goodwill by segment (Details) $ in Millions	9 Months Ended
	Sep. 30, 2024 USD ($)
Goodwill
Balance at beginning of the period	$ 3,140.6
Changes in foreign currency exchange rates	9.9
Balance at end of the period	3,150.5
Options
Goodwill
Balance at beginning of the period	305.8
Changes in foreign currency exchange rates	0.0
Balance at end of the period	305.8
North American Equities
Goodwill
Balance at beginning of the period	2,004.4
Changes in foreign currency exchange rates	(3.3)
Balance at end of the period	2,001.1
Europe and Asia Pacific
Goodwill
Balance at beginning of the period	563.2
Changes in foreign currency exchange rates	13.2
Balance at end of the period	576.4
Global FX
Goodwill
Balance at beginning of the period	267.2
Changes in foreign currency exchange rates	0.0
Balance at end of the period	$ 267.2