Note 4 - Loans and the Allowance for Loan Losses - Aging Analysis of the Loan Portfolio (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Commercial Portfolio Segment [Member] \| Commercial Loans [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	$ 77,000	$ 457,000
Commercial Portfolio Segment [Member] \| Commercial Loans [Member]
Loans, past due	77,000	513,000
Financing Receivable, Recorded Investment, Nonaccrual Status		56,000
Loans, current	41,865,000	36,571,000
Loans	41,942,000	37,084,000
Commercial Portfolio Segment [Member] \| Agricultural Loans [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	800,000
Commercial Portfolio Segment [Member] \| Agricultural Loans [Member]
Loans, past due	800,000
Financing Receivable, Recorded Investment, Nonaccrual Status
Loans, current	48,246,000	39,856,000
Loans	49,046,000	39,856,000
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	172,000
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Loans, past due	1,910,000	3,130,000
Financing Receivable, Recorded Investment, Nonaccrual Status	1,738,000	3,130,000
Loans, current	213,256,000	188,965,000
Loans	215,166,000	192,095,000
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due		9,000
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Loans, past due	781,000	902,000
Financing Receivable, Recorded Investment, Nonaccrual Status	781,000	893,000
Loans, current	18,171,000	15,286,000
Loans	18,952,000	16,188,000
Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	54,000	472,000
Residential Portfolio Segment [Member] \| Real Estate Loan [Member]
Loans, past due	209,000	562,000
Financing Receivable, Recorded Investment, Nonaccrual Status	155,000	90,000
Loans, current	22,778,000	24,912,000
Loans	22,987,000	25,474,000
Residential Portfolio Segment [Member] \| Equity Lines of Credit [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	216,000	8,000
Residential Portfolio Segment [Member] \| Equity Lines of Credit [Member]
Loans, past due	521,000	320,000
Financing Receivable, Recorded Investment, Nonaccrual Status	305,000	312,000
Loans, current	41,222,000	38,007,000
Loans	41,743,000	38,327,000
Consumer Portfolio Segment [Member] \| Automobile Loan [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	580,000	586,000
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Loans, past due	701,000	651,000
Financing Receivable, Recorded Investment, Nonaccrual Status	121,000	65,000
Loans, current	52,763,000	47,714,000
Loans	53,464,000	48,365,000
Consumer Portfolio Segment [Member] \| Other Loans [Member] \| Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	26,000	15,000
Consumer Portfolio Segment [Member] \| Other Loans [Member]
Loans, past due	26,000	15,000
Financing Receivable, Recorded Investment, Nonaccrual Status
Loans, current	3,587,000	3,567,000
Loans	3,613,000	3,582,000
Financing Receivables 30 to 89 Days Past Due [Member]
Loans, past due	1,925,000	1,547,000
Loans, past due	5,025,000	6,093,000
Financing Receivable, Recorded Investment, Nonaccrual Status	3,100,000	4,546,000
Loans, current	441,888,000	394,878,000
Loans	$ 446,913,000	$ 400,971,000

Financing receivables that are current.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953401-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5111-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953401-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

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