Securities (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Carrying value of securities pledged as collateral to secure public deposits	$ 37.6	$ 43.7
Fair value of investments, carried at less than historical costs	$ 36.1	$ 49.8
Percentage available for sale Securities in unrealized loss positions out of total available for sale securities	51.00%	62.00%