Note 3 - Loan Portfolio by Credit Quality Indicator (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Pass [Member]
Loans and Leases Receivable, Gross	$ 41,878	$ 44,274,000
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	1,749	1,927,000
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	1,488	1,581,000
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member]
Loans and Leases Receivable, Gross	45,115,000	47,782,000	$ 51,774,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Pass [Member]
Loans and Leases Receivable, Gross	18,240,000	18,970,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	75,000	18,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	247,000	205,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member]
Loans and Leases Receivable, Gross	18,562,000	19,193,000	19,188,000
Real Estate Portfolio Segment [Member] | Commercial [Member] | Pass [Member]
Loans and Leases Receivable, Gross	322,522,000	320,566,000
Real Estate Portfolio Segment [Member] | Commercial [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	6,565,000	13,653,000
Real Estate Portfolio Segment [Member] | Commercial [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	18,285,000	12,043,000
Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans and Leases Receivable, Gross	347,372,000	346,262,000	341,845,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Pass [Member]
Loans and Leases Receivable, Gross	33,618,000	36,516,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	1,001,000	913,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	1,351,000	2,678,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member]
Loans and Leases Receivable, Gross	35,970,000	40,107,000	48,611,000
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Pass [Member]
Loans and Leases Receivable, Gross	$ 9,849,000	9,413,000
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Substandard [Member]
Loans and Leases Receivable, Gross
Real Estate Portfolio Segment [Member] | Residential Construction [Member]
Loans and Leases Receivable, Gross	$ 9,849,000	9,413,000	10,030,000
Real Estate Portfolio Segment [Member] | Residential [Member] | Pass [Member]
Loans and Leases Receivable, Gross	176,393,000	177,054,000
Real Estate Portfolio Segment [Member] | Residential [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	8,418,000	8,546,000
Real Estate Portfolio Segment [Member] | Residential [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	10,868,000	11,402,000
Real Estate Portfolio Segment [Member] | Residential [Member]
Loans and Leases Receivable, Gross	195,679,000	197,002,000	202,878,000
Real Estate Portfolio Segment [Member] | Farmland [Member] | Pass [Member]
Loans and Leases Receivable, Gross	61,104,000	56,798,000
Real Estate Portfolio Segment [Member] | Farmland [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	1,029,000	930,000
Real Estate Portfolio Segment [Member] | Farmland [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	4,152,000	4,052,000
Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans and Leases Receivable, Gross	66,285,000	61,780,000	51,572,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Pass [Member]
Loans and Leases Receivable, Gross	19,129,000	20,038,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	119,000	156,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	413,000	411,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member]
Loans and Leases Receivable, Gross	19,661,000	20,605,000	21,705,000
Consumer and Other Portfolio Segment [Member] | Other [Member] | Pass [Member]
Loans and Leases Receivable, Gross	15,746,000	16,467,000
Consumer and Other Portfolio Segment [Member] | Other [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	22,000	25,000
Consumer and Other Portfolio Segment [Member] | Other [Member]
Loans and Leases Receivable, Gross	15,768,000	16,492,000	6,031,000
Pass [Member]
Loans and Leases Receivable, Gross	698,479,000	700,096,000
Special Mention [Member]
Loans and Leases Receivable, Gross	18,956,000	26,143,000
Substandard [Member]
Loans and Leases Receivable, Gross	36,826,000	32,397,000
Loans and Leases Receivable, Gross	$ 754,261,000	$ 758,636,000	$ 753,634,000