Revenue from Contracts with Clients (Client Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 1,052.1	$ 935.8
Trust Fees Receivable, net
Disaggregation of Revenue [Line Items]
Total Client Receivables	925.2	819.3
Contract with customer, asset, allowance for credit loss	10.9	7.2
Other
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 126.9	$ 116.5