v3.25.1
Note 6 - Fair Value Measurements - Level of Fair Value (Details) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Total investment securities $ 362.7 $ 337.1
Variable Interest Entity, Primary Beneficiary [Member]    
Total investment securities 713.4 502.1
Fair Value, Recurring [Member]    
Cash equivalents 727.8 821.7
Total investment securities 1,076.1 839.2
Other 11.1  
Total assets 1,815.0 1,673.6
Long-term debt 386.5 [1] 383.3 [2]
Contingent consideration 33.9 30.4
Other 7.7 13.6
Total liabilities 474.3 543.0
Contingent consideration 33.9 30.4
Other 7.7 13.6
Fair Value, Recurring [Member] | Derivatives Used in Consolidated Seeded Investment Products [Member]    
Other   12.7
Fair Value, Recurring [Member] | Deferred Bonuses Hedge [Member]    
Derivative liabilities 46.2 115.7
Fair Value, Recurring [Member] | Other Investment Securities [Member]    
Total investment securities 362.7 337.1
Fair Value, Recurring [Member] | Variable Interest Entity, Primary Beneficiary [Member]    
Total investment securities 713.4 502.1
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Cash equivalents 727.8 821.7
Total investment securities 531.1 534.4
Other 0.0  
Total assets 1,258.9 1,356.1
Long-term debt 0.0 [1] 0.0 [2]
Contingent consideration 0.0 0.0
Other 2.0 1.9
Total liabilities 2.0 1.9
Contingent consideration 0.0 0.0
Other 2.0 1.9
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Derivatives Used in Consolidated Seeded Investment Products [Member]    
Other   0.0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Deferred Bonuses Hedge [Member]    
Derivative liabilities 0.0 0.0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other Investment Securities [Member]    
Total investment securities 292.4 273.8
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Variable Interest Entity, Primary Beneficiary [Member]    
Total investment securities 238.7 260.6
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Cash equivalents 0.0 0.0
Total investment securities 505.9 275.2
Other 9.3  
Total assets 515.2 285.4
Long-term debt 386.5 [1] 383.3 [2]
Contingent consideration 0.0 0.0
Other 5.7 11.7
Total liabilities 392.2 395.0
Contingent consideration 0.0 0.0
Other 5.7 11.7
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Derivatives Used in Consolidated Seeded Investment Products [Member]    
Other   10.2
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Deferred Bonuses Hedge [Member]    
Derivative liabilities 0.0 0.0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Investment Securities [Member]    
Total investment securities 31.2 33.7
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Variable Interest Entity, Primary Beneficiary [Member]    
Total investment securities 474.7 241.5
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]    
Cash equivalents 0.0 0.0
Total investment securities 9.0 2.0
Other 1.8  
Total assets 10.8 4.5
Long-term debt 0.0 [1] 0.0 [2]
Contingent consideration 33.9 30.4
Other 0.0 0.0
Total liabilities 80.1 146.1
Contingent consideration 33.9 30.4
Other 0.0 0.0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Derivatives Used in Consolidated Seeded Investment Products [Member]    
Other   2.5
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Deferred Bonuses Hedge [Member]    
Derivative liabilities 46.2 115.7
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Investment Securities [Member]    
Total investment securities 9.0 2.0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Variable Interest Entity, Primary Beneficiary [Member]    
Total investment securities 0.0 0.0
Fair Value, Recurring [Member] | Fair Value Measured at Net Asset Value Per Share [Member]    
Cash equivalents 0.0 [3] 0.0 [4]
Total investment securities 30.1 [3] 27.6 [4]
Other [3] 0.0  
Total assets 30.1 [3] 27.6 [4]
Long-term debt 0.0 [1],[3] 0.0 [2],[4]
Contingent consideration 0.0 [3] 0.0 [4]
Other 0.0 [3] 0.0 [4]
Total liabilities 0.0 [3] 0.0 [4]
Contingent consideration 0.0 [3] 0.0 [4]
Other 0.0 [3] 0.0 [4]
Fair Value, Recurring [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Derivatives Used in Consolidated Seeded Investment Products [Member]    
Other [4]   0.0
Fair Value, Recurring [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Deferred Bonuses Hedge [Member]    
Derivative liabilities 0.0 [3] 0.0 [4]
Fair Value, Recurring [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Other Investment Securities [Member]    
Total investment securities 30.1 [3] 27.6 [4]
Fair Value, Recurring [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Variable Interest Entity, Primary Beneficiary [Member]    
Total investment securities $ 0.0 [3] $ 0.0 [4]
[1] Carried at amortized cost in our Consolidated Balance Sheets and disclosed in this table at fair value.
[2] Carried at amortized cost in our Condensed Consolidated Balance Sheets and disclosed in this table at fair value.
[3] Certain seeded investment products that do not have a readily determinable fair value have been measured at fair value using the net asset value (“NAV”) as a practical expedient and have not been categorized in the fair value hierarchy.
[4] Certain seeded investment products that do not have a readily determinable fair value have been measured at fair value using the NAV as a practical expedient and have not been categorized in the fair value hierarchy.