Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Real Estate Acquired Through Foreclosure [Roll Forward]
Beginning balance	$ 8.5	$ 14.4
Additions	0.9	8.4
Valuation adjustments	0.0	(0.3)
Dispositions	(1.2)	(1.4)
Ending balance	8.2	$ 21.1
Carrying values of foreclosed residential real estate properties	3.1		$ 2.3
Consumer mortgage loans collateralized by residential real estate property in the process of foreclosure	$ 0.8		$ 1.4