v3.25.1
Note 7 - Goodwill and Intangible Assets - Intangible Assets and Goodwill (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Intangible assets, amortization $ (2.8) $ (0.1)
Accumulated amortization, balance (62.8) (62.1)
Foreign currency translation, accumulated amortization (1.2) (1.0)
Accumulated amortization, balance (66.8) (61.2)
Net intangible assets, balance 2,473.3 2,431.3
Net intangible assets 0.0  
Foreign currency translation, Net intangible assets 9.9 (4.5)
Net intangible assets, balance 2,480.4 2,426.7
Goodwill, balance 1,550.4 1,290.3
Goodwill, addition 16.0  
Foreign currency translation, Goodwill 20.8 (8.1)
Goodwill, balance 1,587.2 1,282.2
Balance 54.1  
Foreign currency translation, accumulated amortization 1.2 1.0
Client Relationships [Member]    
Balance 86.1  
Intangible assets, amortization 0.0 0.0
Additions 0.0  
Foreign currency translation, definite-lived intangible assets 1.3 (1.3)
Balance 87.4  
Balance   68.6
Foreign currency translation, definite-lived intangible assets 1.3 (1.3)
Balance   67.3
Investment Management Agreements [Member]    
Balance 28.0  
Additions 0.0  
Foreign currency translation, definite-lived intangible assets 0.0  
Balance 28.0  
Foreign currency translation, definite-lived intangible assets 0.0  
Definite Lived Trademarks [Member]    
Balance 5.5  
Additions 0.0  
Foreign currency translation, definite-lived intangible assets 0.0  
Balance 5.5  
Foreign currency translation, definite-lived intangible assets 0.0  
Investment Management Agreements [Member]    
Balance 2,056.5 2,064.8
Foreign currency translation, indefinite-lived intangible assets 9.8 (4.2)
Balance 2,066.3 2,060.6
Foreign currency translation 9.8 (4.2)
Trademarks [Member]    
Balance 360.0 360.0
Foreign currency translation, indefinite-lived intangible assets 0.0 0.0
Balance 360.0 360.0
Foreign currency translation $ 0.0 $ 0.0