Commitments and Credit Risk - Lines of Credit (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Commitments and Credit Risk
Letters of credit outstanding, amount	$ 16.7	$ 13.4
Commercial lines of credit
Commitments and Credit Risk
Letters of credit outstanding, amount	1,800.0	1,300.0
Open-end consumer lines of credit
Commitments and Credit Risk
Letters of credit outstanding, amount	$ 199.2	$ 175.7