Note 4 - Allowance for Loan Losses - Loans by Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans	$ 461,452	$ 444,195
Pass [Member]
Loans	456,300	428,225
Special Mention [Member]
Loans	2,289	12,964
Special Mention Nonaccrual [Member]
Loans	727
Substandard [Member]
Loans	1,224	2,005
Substandard Nonaccrual [Member]
Loans	898	804
Doubtful [Member]
Loans	14	197
Construction Loan Portfolio Segment [Member] | Residential [Member]
Loans	20,143	15,221
Construction Loan Portfolio Segment [Member] | Residential [Member] | Pass [Member]
Loans	20,143	15,221
Construction Loan Portfolio Segment [Member] | Residential [Member] | Special Mention [Member]
Loans
Construction Loan Portfolio Segment [Member] | Residential [Member] | Special Mention Nonaccrual [Member]
Loans
Construction Loan Portfolio Segment [Member] | Residential [Member] | Substandard [Member]
Loans
Construction Loan Portfolio Segment [Member] | Residential [Member] | Substandard Nonaccrual [Member]
Loans
Construction Loan Portfolio Segment [Member] | Residential [Member] | Doubtful [Member]
Loans
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member]
Loans	21,343	35,601
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member] | Pass [Member]
Loans	21,035	31,433
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member] | Special Mention [Member]
Loans		3,987
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member] | Special Mention Nonaccrual [Member]
Loans	266
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member] | Substandard [Member]
Loans
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member] | Substandard Nonaccrual [Member]
Loans	42	181
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member] | Doubtful [Member]
Loans
Real Estate Portfolio Segment [Member] | Residential [Member]
Loans	134,721	121,649
Real Estate Portfolio Segment [Member] | Residential [Member] | Pass [Member]
Loans	133,447	120,575
Real Estate Portfolio Segment [Member] | Residential [Member] | Special Mention [Member]
Loans	488	342
Real Estate Portfolio Segment [Member] | Residential [Member] | Special Mention Nonaccrual [Member]
Loans	221
Real Estate Portfolio Segment [Member] | Residential [Member] | Substandard [Member]
Loans	326	559
Real Estate Portfolio Segment [Member] | Residential [Member] | Substandard Nonaccrual [Member]
Loans	239
Real Estate Portfolio Segment [Member] | Residential [Member] | Doubtful [Member]
Loans		173
Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans	188,677	173,999
Real Estate Portfolio Segment [Member] | Commercial [Member] | Pass [Member]
Loans	185,974	165,760
Real Estate Portfolio Segment [Member] | Commercial [Member] | Special Mention [Member]
Loans	1,646	7,386
Real Estate Portfolio Segment [Member] | Commercial [Member] | Special Mention Nonaccrual [Member]
Loans
Real Estate Portfolio Segment [Member] | Commercial [Member] | Substandard [Member]
Loans	586	644
Real Estate Portfolio Segment [Member] | Commercial [Member] | Substandard Nonaccrual [Member]
Loans	471	209
Real Estate Portfolio Segment [Member] | Commercial [Member] | Doubtful [Member]
Loans
Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans	59,591	61,197
Commercial Industrial and Agricultural Portfolio Segment [Member] | Pass [Member]
Loans	59,145	59,042
Commercial Industrial and Agricultural Portfolio Segment [Member] | Special Mention [Member]
Loans	155	1,249
Commercial Industrial and Agricultural Portfolio Segment [Member] | Special Mention Nonaccrual [Member]
Loans	118
Commercial Industrial and Agricultural Portfolio Segment [Member] | Substandard [Member]
Loans	13	503
Commercial Industrial and Agricultural Portfolio Segment [Member] | Substandard Nonaccrual [Member]
Loans	146	379
Commercial Industrial and Agricultural Portfolio Segment [Member] | Doubtful [Member]
Loans	14	24
Equity Lines Portfolio Segment [Member]
Loans	29,294	28,835
Equity Lines Portfolio Segment [Member] | Pass [Member]
Loans	28,873	28,536
Equity Lines Portfolio Segment [Member] | Special Mention [Member]
Loans
Equity Lines Portfolio Segment [Member] | Special Mention Nonaccrual [Member]
Loans	122
Equity Lines Portfolio Segment [Member] | Substandard [Member]
Loans	299	299
Equity Lines Portfolio Segment [Member] | Substandard Nonaccrual [Member]
Loans
Equity Lines Portfolio Segment [Member] | Doubtful [Member]
Loans
Consumer Portfolio Segment [Member]
Loans	7,683	7,693
Consumer Portfolio Segment [Member] | Pass [Member]
Loans	7,683	7,658
Consumer Portfolio Segment [Member] | Special Mention [Member]
Loans
Consumer Portfolio Segment [Member] | Special Mention Nonaccrual [Member]
Loans
Consumer Portfolio Segment [Member] | Substandard [Member]
Loans
Consumer Portfolio Segment [Member] | Substandard Nonaccrual [Member]
Loans		35
Consumer Portfolio Segment [Member] | Doubtful [Member]
Loans