Note 8 - Internal Risk Ratings and Payment Activity (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	$ 785,746	$ 733,078
Excluding Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	636,760	595,004
Pass [Member] | Excluding Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	616,134	566,703
Special Mention [Member] | Excluding Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	523	11,654
Substandard [Member] | Excluding Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	20,103	16,647
Doubtful [Member] | Excluding Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	153,742	147,190
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	54,007	51,157
Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	307,889	286,867
Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	69,088	71,703
Commercial Portfolio Segment [Member] | Pass [Member] | Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	147,662	139,820
Commercial Portfolio Segment [Member] | Pass [Member] | Construction Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	54,007	51,156
Commercial Portfolio Segment [Member] | Pass [Member] | Secured by Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	295,605	268,069
Commercial Portfolio Segment [Member] | Pass [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	66,826	69,571
Commercial Portfolio Segment [Member] | Special Mention [Member] | Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	863
Commercial Portfolio Segment [Member] | Special Mention [Member] | Construction Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
Commercial Portfolio Segment [Member] | Special Mention [Member] | Secured by Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	523	10,569
Commercial Portfolio Segment [Member] | Special Mention [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	222
Commercial Portfolio Segment [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	6,080	6,507
Commercial Portfolio Segment [Member] | Substandard [Member] | Construction Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	1
Commercial Portfolio Segment [Member] | Substandard [Member] | Secured by Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	11,761	8,229
Commercial Portfolio Segment [Member] | Substandard [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	2,262	1,910
Commercial Portfolio Segment [Member] | Doubtful [Member] | Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
Commercial Portfolio Segment [Member] | Doubtful [Member] | Construction Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
Commercial Portfolio Segment [Member] | Doubtful [Member] | Secured by Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
Commercial Portfolio Segment [Member] | Doubtful [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
State and Political Subdivisions Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	52,034	38,087
State and Political Subdivisions Portfolio Segment [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	52,034	38,087
State and Political Subdivisions Portfolio Segment [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
State and Political Subdivisions Portfolio Segment [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	0	0
State and Political Subdivisions Portfolio Segment [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	$ 0	$ 0