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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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