Fair Value (Narrative) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Held-for-Sale, fair value		$ 6,719,000	$ 15,273,000
Contractual principal balance of loans held-for-sale		6,576,000	14,983,000
Difference in amount of loan held-for-sale		143,000	290,000
Impaired loans, carrying amount	[1]	9,293,000	1,575,000
Valuation allowance for loans losses		2,234,000	355,000
Other real estate, carrying value		0	0
Cost of real estate sales charged through operating income			75,000
Impaired Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, carrying amount		9,020,000	663,000
Valuation allowance for loans losses		2,228,000	255,000
Increase (decrease) in provision for loan losses		1,973,000	115,000
Obligations of State and Political Subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other changes in fair value		(60,000)	(75,000)
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		740,994,000	709,786,000
Fair Value, Measurements, Recurring | Obligations of State and Political Subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		273,309,000	247,519,000
Fair Value, Measurements, Recurring | Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		353,000	353,000
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		6,002,000	7,377,000
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Obligations of State and Political Subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		5,649,000	7,024,000
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		$ 353,000	$ 353,000

[1] Unpaid Principal Balance is the remaining contractual payments gross of partial charge-offs and discounts.