Loans (Troubled Debt Restructured Loans) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Troubled debt restructured loans	$ 8.1	$ 10.9
Nonperforming Financial Instruments
Financing Receivable, Recorded Investment [Line Items]
Troubled debt restructured loans	4.1	4.3
Performing Financial Instruments
Financing Receivable, Recorded Investment [Line Items]
Troubled debt restructured loans	$ 4.0	6.6
GNMA insured or guaranteed loan programs | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Troubled debt restructured loans		$ 7.6