Note 3 - Loans - Loan Portfolio by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Loans	$ 775,566	$ 754,283	$ 764,209
Pass [Member]
Loans	737,172	707,965
Special Mention [Member]
Loans	12,248	19,530
Substandard [Member]
Loans	26,146	26,788
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member]
Loans	44,883	47,025	47,934
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Pass [Member]
Loans	42,156	44,250
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Special Mention [Member]
Loans	1,864	1,862
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Substandard [Member]
Loans	863	913
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member]
Loans	21,810	17,080	24,307
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Pass [Member]
Loans	21,110	16,586
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Special Mention [Member]
Loans	163	192
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Substandard [Member]
Loans	537	302
Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans	355,801	349,090	345,181
Real Estate Portfolio Segment [Member] | Commercial [Member] | Pass [Member]
Loans	341,986	327,561
Real Estate Portfolio Segment [Member] | Commercial [Member] | Special Mention [Member]
Loans	4,158	9,403
Real Estate Portfolio Segment [Member] | Commercial [Member] | Substandard [Member]
Loans	9,657	12,126
Real Estate Portfolio Segment [Member] | Commercial Construction [Member]
Loans	35,151	30,358	32,292
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Pass [Member]
Loans	31,324	28,425
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Special Mention [Member]
Loans	1,211	1,349
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Substandard [Member]
Loans	2,616	584
Real Estate Portfolio Segment [Member] | Residential Construction [Member]
Loans	9,230	11,830	9,141
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Pass [Member]
Loans	9,031	11,630
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Special Mention [Member]
Loans	0
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Substandard [Member]
Loans	199	200
Real Estate Portfolio Segment [Member] | Residential [Member]
Loans	200,572	195,580	196,140
Real Estate Portfolio Segment [Member] | Residential [Member] | Pass [Member]
Loans	185,981	178,618
Real Estate Portfolio Segment [Member] | Residential [Member] | Special Mention [Member]
Loans	3,636	5,659
Real Estate Portfolio Segment [Member] | Residential [Member] | Substandard [Member]
Loans	10,955	11,303
Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans	70,194	66,877	70,137
Real Estate Portfolio Segment [Member] | Farmland [Member] | Pass [Member]
Loans	68,144	65,075
Real Estate Portfolio Segment [Member] | Farmland [Member] | Special Mention [Member]
Loans	1,102	839
Real Estate Portfolio Segment [Member] | Farmland [Member] | Substandard [Member]
Loans	948	963
Consumer and Other Portfolio Segment [Member] | Consumer [Member]
Loans	19,134	19,695	19,936
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Pass [Member]
Loans	18,649	19,072
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Special Mention [Member]
Loans	114	226
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Substandard [Member]
Loans	371	397
Consumer and Other Portfolio Segment [Member] | Other [Member]
Loans	18,791	16,748	$ 19,141
Consumer and Other Portfolio Segment [Member] | Other [Member] | Pass [Member]
Loans	18,791	16,748
Consumer and Other Portfolio Segment [Member] | Other [Member] | Special Mention [Member]
Loans	0
Consumer and Other Portfolio Segment [Member] | Other [Member] | Substandard [Member]
Loans