Note 4 - Loans - Loans by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Loans	$ 756,906	$ 728,758
Commercial Loans [Member]
Loans	485,618	478,252
Accruing Loans [Member]
Loans	270,602	249,725
Nonaccrual Loans [Member]
Loans	686	781
Subtotal, Other Loans [Member]
Loans	271,288	250,506
Pass [Member] | Commercial Loans [Member]
Loans	465,730	459,047
Special Mention [Member] | Commercial Loans [Member]
Loans	9,335	11,409
Substandard [Member] | Commercial Loans [Member]
Loans	10,553	7,796
Doubtful [Member] | Commercial Loans [Member]
Loans	0	0
Loss [Member] | Commercial Loans [Member]
Loans	0	0
Residential Portfolio Segment [Member]
Loans	152,257	144,260
Residential Portfolio Segment [Member] | Commercial Loans [Member]
Loans	23,514	26,366
Residential Portfolio Segment [Member] | Accruing Loans [Member]
Loans	128,287	117,286
Residential Portfolio Segment [Member] | Nonaccrual Loans [Member]
Loans	456	608
Residential Portfolio Segment [Member] | Subtotal, Other Loans [Member]
Loans	128,743	117,894
Residential Portfolio Segment [Member] | Pass [Member] | Commercial Loans [Member]
Loans	22,866	25,506
Residential Portfolio Segment [Member] | Special Mention [Member] | Commercial Loans [Member]
Loans	331	394
Residential Portfolio Segment [Member] | Substandard [Member] | Commercial Loans [Member]
Loans	317	466
Residential Portfolio Segment [Member] | Doubtful [Member] | Commercial Loans [Member]
Loans	0	0
Residential Portfolio Segment [Member] | Loss [Member] | Commercial Loans [Member]
Loans	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans	253,791	243,830
Commercial Real Estate Portfolio Segment [Member] | Commercial Loans [Member]
Loans	253,791	243,830
Commercial Real Estate Portfolio Segment [Member] | Accruing Loans [Member]
Loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Nonaccrual Loans [Member]
Loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Subtotal, Other Loans [Member]
Loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Commercial Loans [Member]
Loans	237,484	233,523
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Commercial Loans [Member]
Loans	7,695	4,911
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Commercial Loans [Member]
Loans	8,612	5,396
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member] | Commercial Loans [Member]
Loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Loss [Member] | Commercial Loans [Member]
Loans	0	0
Construction, Land Acquisition and Development [Member]
Loans	26,805	18,357
Construction, Land Acquisition and Development [Member] | Commercial Loans [Member]
Loans	24,055	14,895
Construction, Land Acquisition and Development [Member] | Accruing Loans [Member]
Loans	2,750	3,462
Construction, Land Acquisition and Development [Member] | Nonaccrual Loans [Member]
Loans	0	0
Construction, Land Acquisition and Development [Member] | Subtotal, Other Loans [Member]
Loans	2,750	3,462
Construction, Land Acquisition and Development [Member] | Pass [Member] | Commercial Loans [Member]
Loans	23,716	14,101
Construction, Land Acquisition and Development [Member] | Special Mention [Member] | Commercial Loans [Member]
Loans	333	346
Construction, Land Acquisition and Development [Member] | Substandard [Member] | Commercial Loans [Member]
Loans	6	448
Construction, Land Acquisition and Development [Member] | Doubtful [Member] | Commercial Loans [Member]
Loans	0	0
Construction, Land Acquisition and Development [Member] | Loss [Member] | Commercial Loans [Member]
Loans	0	0
Commercial and Industrial [Member]
Loans	146,048	150,758
Commercial and Industrial [Member] | Commercial Loans [Member]
Loans	142,485	146,716
Commercial and Industrial [Member] | Accruing Loans [Member]
Loans	3,563	4,042
Commercial and Industrial [Member] | Nonaccrual Loans [Member]
Loans	0
Commercial and Industrial [Member] | Subtotal, Other Loans [Member]
Loans	3,563	4,042
Commercial and Industrial [Member] | Pass [Member] | Commercial Loans [Member]
Loans	140,427	142,794
Commercial and Industrial [Member] | Special Mention [Member] | Commercial Loans [Member]
Loans	882	2,794
Commercial and Industrial [Member] | Substandard [Member] | Commercial Loans [Member]
Loans	1,176	1,128
Commercial and Industrial [Member] | Doubtful [Member] | Commercial Loans [Member]
Loans	0	0
Commercial and Industrial [Member] | Loss [Member] | Commercial Loans [Member]
Loans	0	0
Consumer Portfolio Segment [Member]
Loans	138,734	127,844
Consumer Portfolio Segment [Member] | Commercial Loans [Member]
Loans	2,502	2,736
Consumer Portfolio Segment [Member] | Accruing Loans [Member]
Loans	136,002	124,935
Consumer Portfolio Segment [Member] | Nonaccrual Loans [Member]
Loans	230	173
Consumer Portfolio Segment [Member] | Subtotal, Other Loans [Member]
Loans	136,232	125,108
Consumer Portfolio Segment [Member] | Pass [Member] | Commercial Loans [Member]
Loans	2,373	2,699
Consumer Portfolio Segment [Member] | Special Mention [Member] | Commercial Loans [Member]
Loans	94
Consumer Portfolio Segment [Member] | Substandard [Member] | Commercial Loans [Member]
Loans	35	37
Consumer Portfolio Segment [Member] | Doubtful [Member] | Commercial Loans [Member]
Loans	0	0
Consumer Portfolio Segment [Member] | Loss [Member] | Commercial Loans [Member]
Loans	0	0
State and Political Subdivisions [Member]
Loans	39,271	43,709
State and Political Subdivisions [Member] | Commercial Loans [Member]
Loans	39,271	43,709
State and Political Subdivisions [Member] | Accruing Loans [Member]
Loans	0	0
State and Political Subdivisions [Member] | Nonaccrual Loans [Member]
Loans	0	0
State and Political Subdivisions [Member] | Subtotal, Other Loans [Member]
Loans	0	0
State and Political Subdivisions [Member] | Pass [Member] | Commercial Loans [Member]
Loans	38,864	40,424
State and Political Subdivisions [Member] | Special Mention [Member] | Commercial Loans [Member]
Loans	0	2,964
State and Political Subdivisions [Member] | Substandard [Member] | Commercial Loans [Member]
Loans	407	321
State and Political Subdivisions [Member] | Doubtful [Member] | Commercial Loans [Member]
Loans	0	0
State and Political Subdivisions [Member] | Loss [Member] | Commercial Loans [Member]
Loans	$ 0	$ 0