Note 4 - Loans and Allowance for Loan Losses - Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans past due	$ 16,690	$ 14,828
Loans, current	751,375	754,491
Loans	768,065	769,319
Residential Portfolio Segment [Member]
Loans past due	8,476	7,727
Loans, current	296,717	301,436
Loans	305,193	309,163
Commercial Real Estate Portfolio Segment [Member]
Loans	211,687	213,446
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans past due	1,198	515
Loans, current	68,451	73,058
Loans	69,649	73,573
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans past due	3,011	2,378
Loans, current	101,672	99,193
Loans	104,683	101,571
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans past due	291	169
Loans, current	37,064	38,133
Loans	37,355	38,302
Commercial and Industrial Portfolio Segment [Member]
Loans past due	478	737
Loans, current	113,086	106,352
Loans	113,564	107,089
Consumer Portfolio Segment [Member]
Loans	137,621	139,621
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans past due	1,554	1,754
Loans, current	66,198	66,872
Loans	67,752	68,626
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans past due	680	389
Loans, current	20,918	21,042
Loans	21,598	21,431
Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans past due	1,002	1,159
Loans, current	47,269	48,405
Loans	48,271	49,564
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	9,202	8,232
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans past due	5,625	5,383
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans past due	723	194
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans past due	417	140
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans past due	181	303
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans past due	1,203	1,257
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans past due	325	90
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans past due	728	865
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	2,448	1,911
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans past due	987	671
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans past due	186	161
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans past due	371
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans past due	134
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans past due	83	243
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans past due	184	346
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans past due	328	272
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans past due	175	218
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	5,040	4,685
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans past due	1,864	1,673
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans past due	289	160
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans past due	2,223	2,238
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans past due	157	169
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans past due	214	191
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans past due	167	151
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans past due	27	27
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans past due	$ 99	$ 76