Note 7 - Loans and Allowance for Loan Losses - Aging Analysis of Loans (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
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	$ 0
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	227,000	227,000
Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Loans, past due	227,000	227,000
Loans, current	114,227,000	115,289,000
Loans, net of unearned income	114,454,000	115,516,000
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	1,158,000	421,000
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	848,000	1,448,000
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Loans, past due	2,006,000	1,869,000
Loans, current	339,154,000	353,265,000
Loans, net of unearned income	341,160,000	355,134,000
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	0	42,000
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	2,500,000	2,376,000
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Loans, past due	2,500,000	2,418,000
Loans, current	391,473,000	383,968,000
Loans, net of unearned income	393,973,000	386,386,000
Real Estate Portfolio Segment [Member]
Loans, net of unearned income	849,587,000	857,036,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	7,000	42,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	16,000	43,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans, past due	23,000	85,000
Loans, current	47,683,000	48,294,000
Loans, net of unearned income	47,706,000	48,379,000
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] | States and Political Subdivisions [Member]
Loans, past due	0	0
Loans, current	19,922,000	17,643,000
Loans, net of unearned income	19,922,000	17,643,000
Commercial Portfolio Segment [Member] | Commercial Other [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	16,000	62,000
Commercial Portfolio Segment [Member] | Commercial Other [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	16,000	62,000
Loans, current	23,650,000	23,736,000
Loans, net of unearned income	23,666,000	23,798,000
Commercial Portfolio Segment [Member]
Loans, net of unearned income	91,294,000	89,820,000
Consumer Portfolio Segment [Member] | Consumer Secured [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	6,000	9,000
Consumer Portfolio Segment [Member] | Consumer Secured [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	2,000	1,000
Consumer Portfolio Segment [Member] | Consumer Secured [Member]
Loans, past due	8,000	10,000
Loans, current	4,589,000	6,655,000
Loans, net of unearned income	4,597,000	6,665,000
Consumer Portfolio Segment [Member] | Consumer Unsecured [Member] | Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	19,000	18,000
Consumer Portfolio Segment [Member] | Consumer Unsecured [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	19,000	18,000
Loans, current	5,219,000	5,736,000
Loans, net of unearned income	5,238,000	5,754,000
Consumer Portfolio Segment [Member]
Loans, net of unearned income	9,835,000	12,419,000
Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	1,206,000	594,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	3,593,000	4,095,000
Loans, past due	4,799,000	4,689,000
Loans, current	945,917,000	954,586,000
Loans, net of unearned income	$ 950,716,000	$ 959,275,000