Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2021
Real Estate Acquired Through Foreclosure [Roll Forward]
Beginning balance	$ 2.0	$ 2.2	$ 2.5
OREO acquired through acquisition	15.8	$ 0.0
Additions	0.0		0.3
Dispositions	(0.3)		(0.6)
Ending balance	17.5		$ 2.2
Carrying values of foreclosed residential real estate properties	0.2			$ 0.2
Consumer mortgage loans collateralized by residential real estate property in the process of foreclosure	$ 0.4			$ 0.2