Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Repossessed Assets [Abstract]
Balance at beginning of year	$ 13.4	$ 17.5	$ 12.7	$ 2.0
OREO acquired through acquisitions	0.0	0.0	0.0	15.8
Additions	1.7	0.1	2.5	0.1
Write-down of OREO	(0.7)	0.0	(0.8)	0.0
Dispositions	0.0	(0.8)	0.0	(1.1)
Balance at end of year	$ 14.4	$ 16.8	$ 14.4	$ 16.8