Securities Sold Under Agreements to Repurchase - Schedule of Assets and Liabilities Subject to an Enforceable Master Netting Arrangement or Repurchase Agreements (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Interest Rate Swap Agreements
Offsetting Assets And Liabilities [Line Items]
Fair value of investment securities pledged	$ 50.4	$ 58.3
Private Institutions
Offsetting Assets And Liabilities [Line Items]
Fair value of investment securities pledged	508.2	523.4
Government Entities
Offsetting Assets And Liabilities [Line Items]
Fair value of investment securities pledged	$ 1.1	$ 1.3