Investment Securities (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($)
Securities [Line Items]
Available-for-sale securities pledged as collateral | $	$ 103.8	$ 105.9
Collateralized Mortgage Obligations GSE [Member]
Securities [Line Items]
Securities in unrealized loss positions qualitative disclosure number of positions	19
Number of securities, impaired for more than 12 months	16
Unrealized loss of security from book value	6.74%
Government Sponsored Entities (GSE) Mortgage-Backed Securities [Member]
Securities [Line Items]
Securities in unrealized loss positions qualitative disclosure number of positions	19
Number of securities, impaired for more than 12 months	14
Unrealized loss of security from book value	4.69%
US Government Agency Obligations [Member]
Securities [Line Items]
Securities in unrealized loss positions qualitative disclosure number of positions	11
Number of securities, impaired for more than 12 months	6
Unrealized loss of security from book value	4.26%
State and Municipal Tax-Exempt [Member]
Securities [Line Items]
Securities in unrealized loss positions qualitative disclosure number of positions	46
Number of securities, impaired for more than 12 months	20
Number of impaired municipal securities, insured school districts	17
Number of impaired municipal securities, unisured school districts	18
Number of impaired municipal securities, townships insured	4
Number of impaired municipal securities, townships uninsured	7
Unrealized loss of security from book value	10.39%
State and Municipal Taxable [Member]
Securities [Line Items]
Securities in unrealized loss positions qualitative disclosure number of positions	1
Unrealized loss of security from book value	3.42%
Corporate Bonds [Member]
Securities [Line Items]
Securities in unrealized loss positions qualitative disclosure number of positions	11
Number of securities, impaired for more than 12 months	4
Unrealized loss of security from book value	5.00%