Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Foreclosed Residential Real Estate included in Other Real Estate Owned	$ 1.7		$ 2.0
Real Estate Acquired Through Foreclosure [Roll Forward]
Beginning balance	14.4	$ 10.1
Additions	8.4	1.2
Valuation adjustments	0.3	0.0
Dispositions	1.4	0.3
Ending balance	21.1	$ 11.0
Consumer mortgage loans collateralized by residential real estate property in the process of foreclosure	$ 0.5		$ 0.4