Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Entity Information [Line Items]
Off-Balance Sheet, Credit Loss, Liability	$ 20.8	$ 6.2	$ 20.8	$ 6.2	$ 17.8	$ 16.2	$ 6.2	$ 3.8
Provision for credit loss expense	(9.9)	1.7	(22.1)	(55.6)
Credit Extension Commitments	4,711.7		4,711.7			5,173.3
Unused Credit Card Lines
Entity Information [Line Items]
Credit Extension Commitments	809.7		809.7			827.6
Standby Letter of Credit
Entity Information [Line Items]
Credit Extension Commitments	96.7		96.7			$ 93.8
Cumulative effect, period of adoption, adjusted balance
Entity Information [Line Items]
Provision for credit loss expense	$ 3.0	$ 0.0	$ 4.6	$ 2.4