ACQUISITIONS - Acquisition Summary (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Business Acquisition [Line Items]
Goodwill	$ 8,047.2		$ 7,907.3
Payments for merger related costs	0.4
Prior year business combinations, net tangible assets adjustments	0.6
Prior year business combinations, goodwill adjustments	1.0
Weighted average useful lives of definite-lived intangible assets acquired from other acquisitions		9 years
Finite-lived intangible assets acquired	0.0
Global Institutional and Specialty
Business Acquisition [Line Items]
Goodwill	$ 1,037.7		613.2
Business Acquisitions and Investment
Business Acquisition [Line Items]
Net tangible assets (liabilities) acquired			0.1
Identifiable intangible assets			14.4
Goodwill			22.8
Total aggregate purchase price			37.3
Acquisition related liabilities and contingent consideration			(2.0)
Net cash paid for acquisitions, including acquisition-related liabilities and contingent consideration			35.3
Business Acquisitions and Investment | Customer relationships
Business Acquisition [Line Items]
Identifiable intangible assets			11.0
Business Acquisitions and Investment | Trademarks
Business Acquisition [Line Items]
Identifiable intangible assets			1.8
Business Acquisitions and Investment | Other technology
Business Acquisition [Line Items]
Identifiable intangible assets			$ 1.6