Note 3 - Loans Receivable - Past Due and Non-accrual Status of Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans, past due	$ 1,898	$ 4,141
Loans, current	464,445	440,054
Loans	466,343	444,195
Loans, nonaccrual loans	1,454	1,144
Construction Loan Portfolio Segment [Member] | Residential [Member]
Loans, past due
Loans, current	19,062	15,221
Loans	19,062	15,221
Loans, nonaccrual loans
Construction Loan Portfolio Segment [Member] | Land Acquisition Development And Commercial [Member]
Loans, past due	253	317
Loans, current	25,795	35,284
Loans	26,048	35,601
Loans, nonaccrual loans	124	274
Real Estate Portfolio Segment [Member] | Residential [Member]
Loans, past due	943	2,005
Loans, current	140,785	119,644
Loans	141,728	121,649
Loans, nonaccrual loans	546	173
Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans, past due	219	506
Loans, current	187,675	173,493
Loans	187,894	173,999
Loans, nonaccrual loans	468	209
Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans, past due	74	665
Loans, current	54,859	60,532
Loans	54,933	61,197
Loans, nonaccrual loans	169	403
Equity Lines Portfolio Segment [Member]
Loans, past due	407	593
Loans, current	28,268	28,242
Loans	28,675	28,835
Loans, nonaccrual loans	147	49
Consumer Portfolio Segment [Member]
Loans, past due	2	55
Loans, current	8,001	7,638
Loans	8,003	7,693
Loans, nonaccrual loans		36
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	1,592	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	253	43
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Residential [Member]
Loans, past due	870	589
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans, past due	136	278
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans, past due	28	130
Financing Receivables, 30 to 59 Days Past Due [Member] | Equity Lines Portfolio Segment [Member]
Loans, past due	303	544
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans, past due	2	17
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	306	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	73	870
Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans, past due	83	19
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Industrial and Agricultural Portfolio Segment [Member]
Loans, past due	46	143
Financing Receivables, 60 to 89 Days Past Due [Member] | Equity Lines Portfolio Segment [Member]
Loans, past due	104	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