Note 8 - Past Due Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	$ 4,614	$ 4,219
Loans current	775,057	728,859
Loans and leases receivable	779,671	733,078
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	1,248	1,966
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	577	633
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	2,789	1,620
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	1,666	511
Loans current	158,615	146,679
Loans and leases receivable	160,281	147,190
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	58	25
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	247	429
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	1,361	57
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Loans current	52,143	51,157
Loans and leases receivable	52,143	51,157
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	1,469	1,629
Loans current	303,396	285,238
Loans and leases receivable	304,865	286,867
Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	736	899
Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	86	0
Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	647	730
Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	621	234
Loans current	69,374	71,469
Loans and leases receivable	69,995	71,703
Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	372	24
Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	50	0
Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	199	210
State and Political Subdivisions Portfolio Segment [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Loans current	47,405	38,087
Loans and leases receivable	47,405	38,087
State and Political Subdivisions Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
State and Political Subdivisions Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
State and Political Subdivisions Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Retail Portfolio Segment [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	70	31
Loans current	6,885	6,649
Loans and leases receivable	6,955	6,680
Retail Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	19	23
Retail Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	28	8
Retail Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	23	0
Retail Portfolio Segment [Member] | Family Residential Mortgages [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	613	1,400
Loans current	63,068	54,418
Loans and leases receivable	63,681	55,818
Retail Portfolio Segment [Member] | Family Residential Mortgages [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	744
Retail Portfolio Segment [Member] | Family Residential Mortgages [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	119	152
Retail Portfolio Segment [Member] | Family Residential Mortgages [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	494	504
Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	175	414
Loans current	74,171	75,162
Loans and leases receivable	74,346	75,576
Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	63	251
Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	47	44
Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	$ 65	$ 119