v3.25.2
Revenue from Contracts with Clients (Narrative) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Disaggregation of Revenue [Line Items]        
Trust, investment and other servicing fees $ 1,231.1 $ 1,166.1 $ 2,444.9 $ 2,309.0
Security commissions and trading income 39.6 34.3 78.7 72.2
Other operating income 56.4 924.7 107.1 985.7
Securities Commissions and Trading Income        
Disaggregation of Revenue [Line Items]        
Trust, investment and other servicing fees 37.7 31.0 75.8 64.7
Other Operating Income        
Disaggregation of Revenue [Line Items]        
Trust, investment and other servicing fees $ 10.4 $ 10.0 $ 20.8 $ 19.3