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Note 5 - Investments - General Disclosure (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Seeded investment products	$ 803.6	$ 696.5
Estimated Fair Value	862.3	746.1
Equity method investments	23.1	29.5
Unconsolidated VIEs and VREs [Member]
Seeded investment products	127.1	27.1
Separately Managed Accounts [Member]
Seeded investment products	41.9	44.1
Investments Related to Deferred Compensation Plans [Member]
Estimated Fair Value	29.8	12.0
Other Security Investments [Member]
Estimated Fair Value	5.8	8.1
Current Investments [Member]
Estimated Fair Value	839.2	716.6
Variable Interest Entity, Primary Beneficiary [Member]
Seeded investment products	502.1	382.4
Voting Rights Entity, Primary Beneficiary Aggregated Disclosure [Member]
Seeded investment products	$ 132.5	$ 242.9

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Represents the seeding of various investment products.

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