Note 4 - Loans - Age Analysis of Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans, past due	$ 1,708	$ 2,289
Loans, current	898,712	877,546
Gross loans	900,420	879,835
Recorded investment greater than 90 days and accruing
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	1,168	1,409
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	112	418
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	428	462
Commercial Portfolio Segment [Member]
Loans, past due	133
Loans, current	137,737	142,405
Gross loans	137,870	142,405
Recorded investment greater than 90 days and accruing
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	133
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member]
Gross loans	613,201	585,593
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans, past due
Loans, current	14,723	15,902
Gross loans	14,723	15,902
Recorded investment greater than 90 days and accruing
Commercial Real Estate Portfolio Segment [Member] | Commercial Non-owner Occupied [Member]
Loans, past due
Loans, current	405,192	377,668
Gross loans	405,192	377,668
Recorded investment greater than 90 days and accruing
Commercial Real Estate Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Loans, past due		142
Loans, current	193,286	191,881
Gross loans	193,286	192,023
Recorded investment greater than 90 days and accruing
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Construction Loans [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Non-owner Occupied [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Owner Occupied Loan [Member]
Loans, past due		142
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Construction Loans [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Non-owner Occupied [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Owner Occupied Loan [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction Loans [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Non-owner Occupied [Member]
Loans, past due
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Owner Occupied Loan [Member]
Loans, past due
Residential Portfolio Segment [Member]
Gross loans	101,192	101,912
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Individual Tax Identification Number Loan [Member]
Loans, past due	1,168	1,139
Loans, current	39,257	40,049
Gross loans	40,425	41,188
Recorded investment greater than 90 days and accruing
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Loans, past due		463
Loans, current	30,247	29,914
Gross loans	30,247	30,377
Recorded investment greater than 90 days and accruing
Residential Portfolio Segment [Member] | Home Equity Loan [Member]
Loans, past due	147	141
Loans, current	30,373	30,206
Gross loans	30,520	30,347
Recorded investment greater than 90 days and accruing
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Loan [Member] | Individual Tax Identification Number Loan [Member]
Loans, past due	670	555
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Loans, past due		290
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity Loan [Member]
Loans, past due	140	141
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Loan [Member] | Individual Tax Identification Number Loan [Member]
Loans, past due	70	122
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Loans, past due		173
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity Loan [Member]
Loans, past due	7
Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Loan [Member] | Individual Tax Identification Number Loan [Member]
Loans, past due	428	462
Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Loans, past due
Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity Loan [Member]
Loans, past due
Consumer Portfolio Segment [Member]
Loans, past due	260	404
Loans, current	47,897	49,521
Gross loans	48,157	49,925
Recorded investment greater than 90 days and accruing
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	225	281
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	35	123
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due