Note 8 - Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	$ 7,958	$ 5,941
Loans current	796,350	779,267
Loans and leases receivable	804,308	785,208
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	3,518	1,072
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	623	2,007
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	3,817	2,862
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	2,354	1,607
Loans current	163,027	160,845
Loans and leases receivable	165,381	162,452
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	725	94
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	349	141
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	1,280	1,372
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Loans current	54,717	50,135
Loans and leases receivable	54,717	50,135
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	3,367	1,972
Loans current	310,069	306,618
Loans and leases receivable	313,436	308,590
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	1,754	305
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	0	1,029
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	1,613	638
Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	595	667
Loans current	71,616	67,914
Loans and leases receivable	72,211	68,581
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	166	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	0	352
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	429	291
State and Political Subdivisions Portfolio Segment [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	0	0
Loans current	47,552	43,737
Loans and leases receivable	47,552	43,737
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	103	82
Loans current	6,558	6,703
Loans and leases receivable	6,661	6,785
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	72	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	31	35
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	0	24
Retail Portfolio Segment [Member] | Family Residential Mortgages [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	1,211	1,265
Loans current	66,620	66,188
Loans and leases receivable	67,831	67,453
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	746	544
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	0	245
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	465	476
Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans past due	328	348
Loans current	76,191	77,127
Loans and leases receivable	76,519	77,475
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	55	82
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	243	205
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	$ 30	$ 61