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Note 4 - Investments - General Disclosure (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Seeded investment products	$ 1,408.5	$ 803.6
Estimated Fair Value	1,490.0	862.3
Equity method investments	17.8	23.1
Other non-current investments	8.8	0.0
Unconsolidated VIEs and VREs [Member]
Seeded investment products	149.8	127.1
Separately Managed Accounts [Member]
Seeded investment products	33.4	41.9
Investments Related to Deferred Compensation Plans [Member]
Estimated Fair Value	47.8	29.8
Other Security Investments [Member]
Estimated Fair Value	7.1	5.8
Current Investments [Member]
Estimated Fair Value	1,463.4	839.2
Variable Interest Entity, Primary Beneficiary [Member]
Seeded investment products	1,067.5	502.1
Voting Rights Entity, Primary Beneficiary Aggregated Disclosure [Member]
Seeded investment products	$ 157.8	$ 132.5

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- Definition

Represents the seeding of various investment products.

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