Note 3 - Loans - Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Loans	$ 779,443	$ 765,284	$ 770,046
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member]
Loans	47,292	48,122	45,363
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member]
Loans	21,415	16,443	25,246
Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans	349,408	351,172	346,251
Real Estate Portfolio Segment [Member] | Commercial Construction [Member]
Loans	53,570	45,214	36,533
Real Estate Portfolio Segment [Member] | Residential Construction [Member]
Loans	12,897	8,583	8,905
Real Estate Portfolio Segment [Member] | Residential [Member]
Loans	189,153	194,049	196,332
Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans	70,069	67,768	71,903
Consumer and Other Portfolio Segment [Member] | Consumer [Member]
Loans	18,623	18,956	18,677
Consumer and Other Portfolio Segment [Member] | Other [Member]
Loans	$ 17,016	$ 14,977	$ 20,836