Revenue from Contracts with Clients (Contract Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 1,038.3	$ 996.8
Trust Fees Receivable, net
Disaggregation of Revenue [Line Items]
Total Client Receivables	975.0	932.3
Fee receivable allowance	10.5	12.0
Other
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 63.3	$ 64.5