Note 4 - Loans and Allowance for Loan Losses - Loans by Aging Categories (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Loans current	$ 965,956	$ 943,979
Past due	5,665	5,616
Nonaccrual loans	3,029	2,901
Loans	974,650	952,496
Financial Asset, 30 to 59 Days Past Due [Member]
Past due	5,121	4,795
Financial Asset, 60 to 89 Days Past Due [Member]
Past due	544	599
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due		222
Residential Portfolio Segment [Member] | Real Estate Sector [Member]
Loans current	340,982	342,010
Past due	3,885	3,939
Nonaccrual loans	1,997	1,817
Loans	346,864	347,766
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	3,824	3,462
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	61	281
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due		196
Commercial Portfolio Segment [Member] | Real Estate Sector [Member]
Loans current	354,168	351,104
Past due	45	22
Nonaccrual loans	161	234
Loans	354,374	351,360
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	45	22
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Loans current	80,007	84,280
Past due		566
Nonaccrual loans	714	740
Loans	80,721	85,586
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due		388
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due		178
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member]
Loans current	49,177	35,605
Past due	840
Nonaccrual loans
Loans	50,017	35,605
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	407
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	433
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due
Consumer Portfolio Segment [Member]
Loans current	120,442	112,438
Past due	895	1,089
Nonaccrual loans	157	110
Loans	121,494	113,637
Consumer Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	845	923
Consumer Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	50	140
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due		26
Other Portfolio Segment [Member]
Loans current	21,180	18,542
Past due
Nonaccrual loans
Loans	21,180	18,542
Other Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due