Revenue from Contracts with Clients (Contract Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 1,114.9	$ 1,062.3
Trust Fees Receivable, net
Disaggregation of Revenue [Line Items]
Total Client Receivables	1,013.6	956.7
Fee receivable allowance	5.1	5.0
Other
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 101.3	$ 105.6