Note 4 - Loans - Performing and Non-performing Loan Delinquency Status (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Loans past due	$ 835,367	$ 835,207
Performing Financial Instruments [Member]
Loans past due	829,192	830,511
Nonperforming Financial Instruments [Member]
Loans past due	6,175	4,696
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	161,128	164,145
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	810	688
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	263,288	259,904
Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	22,370	20,813
Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	18
Commercial and Industrial [Member] | Performing Financial Instruments [Member]
Loans past due	154,943	150,215
Commercial and Industrial [Member] | Nonperforming Financial Instruments [Member]
Loans past due	1,578	747
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans past due	167,679	176,397
Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans past due	440	387
State and Political Subdivisions [Member] | Performing Financial Instruments [Member]
Loans past due	59,784	59,037
State and Political Subdivisions [Member] | Nonperforming Financial Instruments [Member]
Loans past due	0	0
Commercial Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	3,329	2,874
Financial Asset, 1 to 29 Days Past Due [Member]
Loans past due	827,872	829,714
Financial Asset, 1 to 29 Days Past Due [Member] | Performing Financial Instruments [Member]
Loans past due	824,684	827,442
Financial Asset, 1 to 29 Days Past Due [Member] | Nonperforming Financial Instruments [Member]
Loans past due	3,188	2,272
Financial Asset, 1 to 29 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	160,753	163,690
Financial Asset, 1 to 29 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	569	443
Financial Asset, 1 to 29 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	262,514	259,904
Financial Asset, 1 to 29 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	22,219	20,813
Financial Asset, 1 to 29 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due
Financial Asset, 1 to 29 Days Past Due [Member] | Commercial and Industrial [Member] | Performing Financial Instruments [Member]
Loans past due	153,731	150,108
Financial Asset, 1 to 29 Days Past Due [Member] | Commercial and Industrial [Member] | Nonperforming Financial Instruments [Member]
Loans past due	1,296	677
Financial Asset, 1 to 29 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans past due	165,683	173,890
Financial Asset, 1 to 29 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans past due	163	91
Financial Asset, 1 to 29 Days Past Due [Member] | State and Political Subdivisions [Member] | Performing Financial Instruments [Member]
Loans past due	59,784	59,037
Financial Asset, 1 to 29 Days Past Due [Member] | State and Political Subdivisions [Member] | Nonperforming Financial Instruments [Member]
Loans past due	0	0
Financial Asset, 1 to 29 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	1,160	1,061
Financial Asset, 30 to 59 Days Past Due [Member]
Loans past due	4,611	2,738
Financial Asset, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member]
Loans past due	4,125	2,627
Financial Asset, 30 to 59 Days Past Due [Member] | Nonperforming Financial Instruments [Member]
Loans past due	486	111
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	219	319
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	0
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	774
Financial Asset, 30 to 59 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	151
Financial Asset, 30 to 59 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial and Industrial [Member] | Performing Financial Instruments [Member]
Loans past due	1,177	87
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial and Industrial [Member] | Nonperforming Financial Instruments [Member]
Loans past due		50
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans past due	1,804	2,221
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans past due	52	61
Financial Asset, 30 to 59 Days Past Due [Member] | State and Political Subdivisions [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | State and Political Subdivisions [Member] | Nonperforming Financial Instruments [Member]
Loans past due	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	434	0
Financial Asset, 60 to 89 Days Past Due [Member]
Loans past due	801	652
Financial Asset, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member]
Loans past due	383	442
Financial Asset, 60 to 89 Days Past Due [Member] | Nonperforming Financial Instruments [Member]
Loans past due	418	210
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	156	136
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	109	136
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due
Financial Asset, 60 to 89 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due		0
Financial Asset, 60 to 89 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	18
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial and Industrial [Member] | Performing Financial Instruments [Member]
Loans past due	35	20
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial and Industrial [Member] | Nonperforming Financial Instruments [Member]
Loans past due	278	0
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans past due	192	286
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans past due	13	74
Financial Asset, 60 to 89 Days Past Due [Member] | State and Political Subdivisions [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | State and Political Subdivisions [Member] | Nonperforming Financial Instruments [Member]
Loans past due	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans past due	2,083	2,103
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member]
Loans past due	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Nonperforming Financial Instruments [Member]
Loans past due	2,083	2,103
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	132	109
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and Industrial [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and Industrial [Member] | Nonperforming Financial Instruments [Member]
Loans past due	4	20
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans past due	212	161
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | State and Political Subdivisions [Member] | Performing Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | State and Political Subdivisions [Member] | Nonperforming Financial Instruments [Member]
Loans past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Real Estate Loan [Member] | Nonperforming Financial Instruments [Member]
Loans past due	$ 1,735	$ 1,813