GOODWILL AND INTANGIBLE ASSETS, NET - Goodwill by segment (Details) $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($)
Goodwill
Balance at beginning of the year	$ 2,682.1
Additions	66.4
Changes in foreign currency exchange rates	(18.1)
Balance at end of the year	2,730.4
Options
Goodwill
Balance at beginning of the year	239.4
Additions	66.4
Balance at end of the year	305.8
U.S. Equities
Goodwill
Balance at beginning of the year	1,740.4
Balance at end of the year	1,740.4
European Equities
Goodwill
Balance at beginning of the year	435.1
Changes in foreign currency exchange rates	(18.1)
Balance at end of the year	417.0
Global FX
Goodwill
Balance at beginning of the year	267.2
Balance at end of the year	267.2
Futures
Goodwill
Balance at end of the year	$ 0.0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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