v3.26.1
Goodwill and Acquired Client Relationships - Schedule of Changes in the Components of Acquired Client Relationships (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Total        
Beginning balance, carrying value     $ 1,639.3  
Intangible amortization and impairments $ (7.2) $ (6.3) (56.5) $ (89.6)
Ending balance, carrying value 1,577.6   1,577.6  
Acquired Client Relationships        
Total        
Beginning balance, carrying value     1,639.3  
Affiliate transactions     (1.5)  
Intangible amortization and impairments     (56.5)  
Foreign currency translation     (3.7)  
Transfers     0.0  
Ending balance, carrying value 1,577.6   1,577.6  
Affiliate transaction intangible asset, portion attributable to noncontrolling interest     0.4  
Acquired Client Relationships        
Indefinite-lived        
Beginning balance, carrying value     1,484.3  
Intangible amortization and impairments     (43.0)  
Foreign currency translation     (3.7)  
Transfers     (2.9)  
Ending balance, carrying value 1,434.7   1,434.7  
Acquired Client Relationships        
Definite-lived        
Beginning balance, gross carrying value     1,267.4  
Beginning balance, accumulated amortization     (1,112.4)  
Beginning balance, net carrying value     155.0  
Affiliate transactions, gross carrying value     (5.8)  
Affiliate transactions, accumulated depreciation     4.3  
Affiliate transactions, net carrying value     (1.5)  
Intangible amortization and impairments (7.2) $ (6.3) (13.5) $ (12.6)
Foreign currency translation, gross carrying value     (3.8)  
Foreign currency translation, accumulated depreciation     3.8  
Transfers     2.9  
Ending balance, gross carrying value 1,260.7   1,260.7  
Ending balance, accumulated amortization (1,117.8)   (1,117.8)  
Ending balance, net carrying value $ 142.9   $ 142.9