Securities (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) security state	Dec. 31, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
State and Political Subdivisions Securities, Number of States with Highest Volume | state	5
Securities pledged to secure public deposits and other purposes | $	$ 113.1	$ 103.3
Securities held with an unrealized loss position | security	82
Residential Mortgage Backed Securities [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Contractual maturity	1 year
Estimated average life to maturity	2 months
Residential Mortgage Backed Securities [Member] | Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Contractual maturity	50 years
Estimated average life to maturity	34 years