Note 3 - Loans Receivable - Past Due and Non-accrual Status of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans, past due	$ 969	$ 4,141
Loans, current	454,621	440,054
Loans	455,590	444,195
Loans, nonaccrual loans	1,478	1,144
Construction Loan Portfolio Segment [Member] | Residential [Member]
Loans, past due
Loans, current	19,452	15,221
Loans	19,452	15,221
Loans, nonaccrual loans
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member]
Loans, past due		317
Loans, current	38,348	35,284
Loans	38,348	35,601
Loans, nonaccrual loans	313	274
Real Estate Portfolio Segment [Member] | Residential [Member]
Loans, past due	252	2,005
Loans, current	129,253	119,644
Loans	129,505	121,649
Loans, nonaccrual loans	469	173
Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans, past due	54	506
Loans, current	173,749	173,493
Loans	173,803	173,999
Loans, nonaccrual loans	485	209
Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans, past due	165	665
Loans, current	58,162	60,532
Loans	58,327	61,197
Loans, nonaccrual loans	162	403
Equity Lines Portfolio Segment [Member]
Loans, past due	382	593
Loans, current	28,591	28,242
Loans	28,973	28,835
Loans, nonaccrual loans	49	49
Consumer Portfolio Segment [Member]
Loans, past due	116	55
Loans, current	7,066	7,638
Loans	7,182	7,693
Loans, nonaccrual loans		36
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	725	1,601
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction Loan Portfolio Segment [Member] | Residential [Member]
Loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member]
Loans, past due		43
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Residential [Member]
Loans, past due	195	589
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans, past due	54	278
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans, past due	101	130
Financing Receivables, 30 to 59 Days Past Due [Member] | Equity Lines Portfolio Segment [Member]
Loans, past due	259	544
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans, past due	116	17
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	244	1,083
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction Loan Portfolio Segment [Member] | Residential [Member]
Loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member]
Loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Residential [Member]
Loans, past due	57	870
Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans, past due		19
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans, past due	64	143
Financing Receivables, 60 to 89 Days Past Due [Member] | Equity Lines Portfolio Segment [Member]
Loans, past due	123	49
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans, past due		2
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due		1,457
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction Loan Portfolio Segment [Member] | Residential [Member]
Loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member]
Loans, past due		274
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Residential [Member]
Loans, past due		546
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans, past due		209
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans, past due		392
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Equity Lines Portfolio Segment [Member]
Loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans, past due		$ 36