Note 3 - Loan Portfolio by Credit Quality Indicator (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Pass [Member]
Loans and Leases Receivable, Gross	$ 45,696,000	$ 44,274,000
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	871,000	1,927,000
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	1,367,000	1,581,000
Commercial and Agricultural Portfolio Segment [Member] | Commercial [Member]
Loans and Leases Receivable, Gross	47,934,000	47,782,000	$ 52,506,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Pass [Member]
Loans and Leases Receivable, Gross	23,872,000	18,970,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	62,000	18,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	373,000	205,000
Commercial and Agricultural Portfolio Segment [Member] | Agricultural [Member]
Loans and Leases Receivable, Gross	24,307,000	19,193,000	24,019,000
Real Estate Portfolio Segment [Member] | Commercial [Member] | Pass [Member]
Loans and Leases Receivable, Gross	321,052,000	320,566,000
Real Estate Portfolio Segment [Member] | Commercial [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	7,434,000	13,653,000
Real Estate Portfolio Segment [Member] | Commercial [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	16,695,000	12,043,000
Real Estate Portfolio Segment [Member] | Commercial [Member]
Loans and Leases Receivable, Gross	345,181,000	346,262,000	341,167,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Pass [Member]
Loans and Leases Receivable, Gross	29,979,000	36,516,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	1,011,000	913,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	1,302,000	2,678,000
Real Estate Portfolio Segment [Member] | Commercial Construction [Member]
Loans and Leases Receivable, Gross	32,292,000	40,107,000	46,699,000
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Pass [Member]
Loans and Leases Receivable, Gross	9,141,000	9,413,000
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	0	0
Real Estate Portfolio Segment [Member] | Residential Construction [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	0	0
Real Estate Portfolio Segment [Member] | Residential Construction [Member]
Loans and Leases Receivable, Gross	9,141,000	9,413,000	11,327,000
Real Estate Portfolio Segment [Member] | Residential [Member] | Pass [Member]
Loans and Leases Receivable, Gross	176,773,000	177,054,000
Real Estate Portfolio Segment [Member] | Residential [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	8,132,000	8,546,000
Real Estate Portfolio Segment [Member] | Residential [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	11,235,000	11,402,000
Real Estate Portfolio Segment [Member] | Residential [Member]
Loans and Leases Receivable, Gross	196,140,000	197,002,000	202,805,000
Real Estate Portfolio Segment [Member] | Farmland [Member] | Pass [Member]
Loans and Leases Receivable, Gross	68,056,000	56,798,000
Real Estate Portfolio Segment [Member] | Farmland [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	1,119,000	930,000
Real Estate Portfolio Segment [Member] | Farmland [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	962,000	4,052,000
Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans and Leases Receivable, Gross	70,137,000	61,780,000	54,135,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Pass [Member]
Loans and Leases Receivable, Gross	19,386,000	20,038,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	124,000	156,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	426,000	411,000
Consumer and Other Portfolio Segment [Member] | Consumer [Member]
Loans and Leases Receivable, Gross	19,936,000	20,605,000	21,371,000
Consumer and Other Portfolio Segment [Member] | Other [Member] | Pass [Member]
Loans and Leases Receivable, Gross	19,121,000	16,467,000
Consumer and Other Portfolio Segment [Member] | Other [Member] | Special Mention [Member]
Loans and Leases Receivable, Gross	0	0
Consumer and Other Portfolio Segment [Member] | Other [Member] | Substandard [Member]
Loans and Leases Receivable, Gross	20,000	25,000
Consumer and Other Portfolio Segment [Member] | Other [Member]
Loans and Leases Receivable, Gross	19,141,000	16,492,000	6,049,000
Pass [Member]
Loans and Leases Receivable, Gross	713,076,000	700,096,000
Special Mention [Member]
Loans and Leases Receivable, Gross	18,753,000	26,143,000
Substandard [Member]
Loans and Leases Receivable, Gross	32,380,000	32,397,000
Loans and Leases Receivable, Gross	$ 764,209,000	$ 758,636,000	$ 760,078,000