Note 7 - Loans and Allowance for Loan Losses - Risk Category of Loans by Class (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Pass [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Loans, net of unearned income	$ 100,635,000	$ 104,383,000
Pass [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Loans, net of unearned income	317,175,000	324,333,000
Pass [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Loans, net of unearned income	364,031,000	343,894,000
Pass [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans, net of unearned income	45,326,000	46,934,000
Pass [Member] | Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member]
Loans, net of unearned income	20,215,000	17,643,000
Pass [Member] | Commercial Portfolio Segment [Member] | Commercial Other [Member]
Loans, net of unearned income	22,501,000	23,777,000
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Loans, net of unearned income	1,431,000	1,651,000
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Loans, net of unearned income	15,238,000	16,225,000
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Loans, net of unearned income	20,545,000	22,859,000
Special Mention [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans, net of unearned income	865,000	937,000
Special Mention [Member] | Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member]
Loans, net of unearned income	0	0
Special Mention [Member] | Commercial Portfolio Segment [Member] | Commercial Other [Member]
Loans, net of unearned income	0	0
Substandard [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Loans, net of unearned income	7,337,000	9,482,000
Substandard [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Loans, net of unearned income	13,875,000	14,576,000
Substandard [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Loans, net of unearned income	18,116,000	19,633,000
Substandard [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans, net of unearned income	498,000	508,000
Substandard [Member] | Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member]
Loans, net of unearned income	0	0
Substandard [Member] | Commercial Portfolio Segment [Member] | Commercial Other [Member]
Loans, net of unearned income	0	21,000
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Loans, net of unearned income	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Loans, net of unearned income	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Loans, net of unearned income	0	0
Doubtful [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans, net of unearned income	0	0
Doubtful [Member] | Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member]
Loans, net of unearned income	0	0
Doubtful [Member] | Commercial Portfolio Segment [Member] | Commercial Other [Member]
Loans, net of unearned income	0	0
Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Loans, net of unearned income	109,403,000	115,516,000
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Loans, net of unearned income	346,288,000	355,134,000
Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Loans, net of unearned income	402,692,000	386,386,000
Real Estate Portfolio Segment [Member]
Loans, net of unearned income	858,383,000	857,036,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans, net of unearned income	46,689,000	48,379,000
Commercial Portfolio Segment [Member] | States and Political Subdivisions [Member]
Loans, net of unearned income	20,215,000	17,643,000
Commercial Portfolio Segment [Member] | Commercial Other [Member]
Loans, net of unearned income	22,501,000	23,798,000
Commercial Portfolio Segment [Member]
Loans, net of unearned income	89,405,000	89,820,000
Loans, net of unearned income	$ 957,426,000	$ 959,275,000