Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Entity Information [Line Items]
Off-Balance Sheet, Credit Loss, Liability	$ 15.4	$ 17.8	$ 18.4	$ 16.2
Provision for credit loss expense	(8.4)	(12.2)
Credit Extension Commitments	3,761.0		4,069.2
Unused Credit Card Lines
Entity Information [Line Items]
Credit Extension Commitments	826.9		814.0
Standby Letter of Credit
Entity Information [Line Items]
Credit Extension Commitments	97.6		$ 97.1
Cumulative effect, period of adoption, adjusted balance
Entity Information [Line Items]
Provision for credit loss expense	$ (3.0)	$ 1.6