GOODWILL AND INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Indefinite-lived intangible assets
Remaining weighted-average estimated useful life in years	2 years 9 months 18 days
Investment advisory agreements
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	$ 613.9	$ 613.9
Accumulated amortization & impairments	(488.0)	(397.4)
Net carrying amount	$ 125.9	$ 216.5
Indefinite-lived intangible assets
Remaining weighted-average estimated useful life in years		3 years 8 months 12 days