Note 8 - Loans and Allowance for Loan Losses - Aging Analysis of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans, past due	$ 4,231	$ 3,806
Loans, current	1,031,238	1,031,457
Loans, net of unearned income	1,035,469	1,035,263
Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	2,905	2,233
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	1,326	1,573
Real Estate Portfolio Segment [Member]
Loans, net of unearned income	923,894	916,806
Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Loans, past due	87	102
Loans, current	131,289	129,079
Loans, net of unearned income	131,376	129,181
Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	0	15
Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	87	87
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Loans, past due	2,395	1,698
Loans, current	349,443	353,606
Loans, net of unearned income	351,838	355,304
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	2,145	1,160
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	250	538
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Loans, past due	1,701	1,914
Loans, current	438,979	430,407
Loans, net of unearned income	440,680	432,321
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	712	966
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	989	948
Commercial Portfolio Segment [Member]
Loans, net of unearned income	104,018	110,542
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans, past due	47	62
Loans, current	68,425	63,355
Loans, net of unearned income	68,472	63,417
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	47	62
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	0	0
Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member]
Loans, past due	0	0
Loans, current	18,883	27,209
Loans, net of unearned income	18,883	27,209
Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	0	0
Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	0	0
Commercial Portfolio Segment [Member] | Commercial Other [Member]
Loans, past due	0	21
Loans, current	16,663	19,895
Loans, net of unearned income	16,663	19,916
Commercial Portfolio Segment [Member] | Commercial Other [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	0	21
Commercial Portfolio Segment [Member] | Commercial Other [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	0	0
Consumer Portfolio Segment [Member]
Loans, net of unearned income	7,557	7,915
Consumer Portfolio Segment [Member] | Consumer Secured [Member]
Loans, past due	0	0
Loans, current	3,980	4,853
Loans, net of unearned income	3,980	4,853
Consumer Portfolio Segment [Member] | Consumer Secured [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	0	0
Consumer Portfolio Segment [Member] | Consumer Secured [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	0	0
Consumer Portfolio Segment [Member] | Consumer Unsecured [Member]
Loans, past due	1	9
Loans, current	3,576	3,053
Loans, net of unearned income	3,577	3,062
Consumer Portfolio Segment [Member] | Consumer Unsecured [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	1	9
Consumer Portfolio Segment [Member] | Consumer Unsecured [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	$ 0	$ 0