Note 4 - Loans - Loans by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loans	$ 711,902	$ 662,544
Commercial Real Estate Portfolio Segment [Member]
Loans	554,519	517,150
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans	20,263	31,265
Commercial Real Estate Portfolio Segment [Member] | Mortgage Loans [Member]
Loans	460,701	417,138
Commercial Real Estate Portfolio Segment [Member] | Land Loans [Member]
Loans	10,951	10,072
Commercial Real Estate Portfolio Segment [Member] | Farmland Loans [Member]
Loans	62,604	58,675
Commercial Portfolio Segment [Member]
Loans	82,252	69,610
Consumer Portfolio Segment [Member]
Loans	1,314	689
Residential Portfolio Segment [Member]
Loans	35,741	37,161
Agriculture [Member]
Loans	38,076	37,934
Pass [Member]
Loans	700,100	655,030
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans	20,263	30,008
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Mortgage Loans [Member]
Loans	457,150	416,437
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Land Loans [Member]
Loans	10,045	8,901
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loans [Member]
Loans	62,604	58,675
Pass [Member] | Commercial Portfolio Segment [Member]
Loans	77,254	65,313
Pass [Member] | Consumer Portfolio Segment [Member]
Loans	1,273	662
Pass [Member] | Residential Portfolio Segment [Member]
Loans	35,698	37,100
Pass [Member] | Agriculture [Member]
Loans	35,813	37,934
Special Mention [Member]
Loans	8,029	5,019
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans		1,257
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member] | Mortgage Loans [Member]
Loans	2,868
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member] | Land Loans [Member]
Loans
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loans [Member]
Loans
Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans	2,898	3,762
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans
Special Mention [Member] | Residential Portfolio Segment [Member]
Loans
Special Mention [Member] | Agriculture [Member]
Loans	2,263
Substandard [Member]
Loans	3,773	2,495
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member] | Mortgage Loans [Member]
Loans	683	701
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member] | Land Loans [Member]
Loans	906	1,171
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loans [Member]
Loans
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans	2,100	535
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans	41	27
Substandard [Member] | Residential Portfolio Segment [Member]
Loans	43	61
Substandard [Member] | Agriculture [Member]
Loans
Doubtful [Member]
Loans
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member] | Mortgage Loans [Member]
Loans
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member] | Land Loans [Member]
Loans
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member] | Farmland Loans [Member]
Loans
Doubtful [Member] | Commercial Portfolio Segment [Member]
Loans
Doubtful [Member] | Consumer Portfolio Segment [Member]
Loans
Doubtful [Member] | Residential Portfolio Segment [Member]
Loans
Doubtful [Member] | Agriculture [Member]
Loans