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Note 5 - Derivative Instruments - Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Futures [Member]
Notional value of derivative	$ 1,471.3	$ 789.0
Futures [Member] | Seeded Investment Products [Member]
Notional value of derivative	711.9	160.5
Foreign Currency, Forward Contracts and Swaps [Member]
Notional value of derivative	296.6	328.2
Foreign Currency, Forward Contracts and Swaps [Member] | Not Designated as Hedging Instrument, Economic Hedge [Member]
Notional value of derivative	36.9	38.4
Foreign Currency, Forward Contracts and Swaps [Member] | Seeded Investment Products [Member]
Notional value of derivative	286.4	196.6
Credit Default Swaps [Member]
Notional value of derivative	159.5	148.5
Credit Default Swaps [Member] | Seeded Investment Products [Member]
Notional value of derivative	12.7	4.3
Total Return Swaps [Member]
Notional value of derivative	59.4	69.7
Total Return Swaps [Member] | Seeded Investment Products [Member]
Notional value of derivative	32.5	10.3
Interest Rate Swap [Member] | Seeded Investment Products [Member]
Notional value of derivative	15.0	13.9
TBAs [Member]
Notional value of derivative	42.6	9.1
Other [Member] | Seeded Investment Products [Member]
Notional value of derivative	$ 1.6	$ 0.0

X

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 181
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480401/815-10-55-181

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A

+ Details

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X

- Details

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- Details

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- Details

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- Details

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