Revenue from Contracts with Clients (Contract Receivables) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 1,015.0	$ 928.4
Trust Fees Receivable, net
Disaggregation of Revenue [Line Items]
Total Client Receivables	955.6	863.5
Contract with customer, asset, allowance for credit loss	13.9	15.9
Other
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 59.4	$ 64.9