Acquired Credit Impaired Loans, Major Classifications of Acquired Credit Impaired Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	$ 834,204	$ 819,803
Less allowance for loan losses	3,407	3,575
Loans, net	830,797	816,228
Acquired credit impaired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	8,069	9,346
Less allowance for loan losses	0	292
Loans, net	8,069	9,054
Acquired credit impaired loans [Member] | Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	1,008	98
Acquired credit impaired loans [Member] | Commercial, secured by real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	4,264	6,305
Acquired credit impaired loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	2,351	2,471
Acquired credit impaired loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	3	17
Acquired credit impaired loans [Member] | Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	0	0
Acquired credit impaired loans [Member] | Other loans, including deposit overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans gross	$ 443	$ 455