Revenue from Contracts with Clients (Client Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 928.4	$ 937.9
Trust Fees Receivable, net
Disaggregation of Revenue [Line Items]
Total Client Receivables	863.5	882.5
Contract with customer, asset, allowance for credit loss	15.9	13.5
Other
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 64.9	$ 55.4