INVESTMENTS - Deconsolidation Impacts on Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Net increase (decrease) in assets of consolidated investment products	$ (552.8)	$ (371.7)	$ (1,156.9)	$ (643.5)
Net increase (decrease) in liabilities of consolidated investment products	(17.6)	(14.6)	(42.9)	(19.5)
Net increase (decrease) in redeemable non-controlling interests	$ (441.9)	$ (160.6)	$ (623.0)	$ (256.8)