Note 4 - Allowance for Loan Losses - Segregated by Impairment Methodology (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Ending allowance balance, collectively evaluated for impairment	$ 6,476		$ 6,009
Ending allowance balance	8,043	$ 8,923	9,390	$ 8,604
Ending loan balance, individually evaluated for impairment	20,778		22,513
Ending loan balance, collectively evaluated for impairment	754,788		741,696
Ending loan balance	775,566	754,283	764,209
Ending allowance balance, individually evaluated for impairment	1,567		3,381
Commercial [Member] \| Commercial and Agricultural Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	425		555
Ending allowance balance	425	456	555	855
Ending loan balance, individually evaluated for impairment	33		9
Ending loan balance, collectively evaluated for impairment	44,850		47,925
Ending loan balance	44,883	47,025	47,934
Ending allowance balance, individually evaluated for impairment
Commercial [Member] \| Real Estate Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	3,146		2,712
Ending allowance balance	4,663	5,751	5,598	3,851
Ending loan balance, individually evaluated for impairment	17,292		17,463
Ending loan balance, collectively evaluated for impairment	338,509		327,718
Ending loan balance	355,801	349,090	345,181
Ending allowance balance, individually evaluated for impairment	1,517		2,886
Agricultural [Member] \| Commercial and Agricultural Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	238		251
Ending allowance balance	238	168	251	203
Ending loan balance, individually evaluated for impairment	5
Ending loan balance, collectively evaluated for impairment	21,805		24,307
Ending loan balance	21,810	17,080	24,307
Ending allowance balance, individually evaluated for impairment
Commercial Construction [Member] \| Real Estate Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	766		416
Ending allowance balance	770	323	438	691
Ending loan balance, individually evaluated for impairment	72		384
Ending loan balance, collectively evaluated for impairment	35,079		31,908
Ending loan balance	35,151	30,358	32,292
Ending allowance balance, individually evaluated for impairment	4		22
Residential Construction [Member] \| Real Estate Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	11		18
Ending allowance balance	11	13	18	20
Ending loan balance, individually evaluated for impairment
Ending loan balance, collectively evaluated for impairment	9,230		9,141
Ending loan balance	9,230	11,830	9,141
Ending allowance balance, individually evaluated for impairment
Residential [Member] \| Real Estate Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	952		1,172
Ending allowance balance	972	1,396	1,612	1,990
Ending loan balance, individually evaluated for impairment	2,336		3,609
Ending loan balance, collectively evaluated for impairment	198,236		192,531
Ending loan balance	200,572	195,580	196,140
Ending allowance balance, individually evaluated for impairment	20		440
Farmland [Member] \| Real Estate Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	833		763
Ending allowance balance	859	722	796	912
Ending loan balance, individually evaluated for impairment	1,040		1,048
Ending loan balance, collectively evaluated for impairment	69,154		69,089
Ending loan balance	70,194	66,877	70,137
Ending allowance balance, individually evaluated for impairment	26		33
Consumer [Member] \| Consumer and Other Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	84		96
Ending allowance balance	84	80	96	63
Ending loan balance, individually evaluated for impairment
Ending loan balance, collectively evaluated for impairment	19,134		19,936
Ending loan balance	19,134	19,695	19,936
Ending allowance balance, individually evaluated for impairment
Other [Member] \| Consumer and Other Portfolio Segment [Member]
Ending allowance balance, collectively evaluated for impairment	21		26
Ending allowance balance	21	14	26	$ 19
Ending loan balance, individually evaluated for impairment
Ending loan balance, collectively evaluated for impairment	18,791		19,141
Ending loan balance	18,791	$ 16,748	19,141
Ending allowance balance, individually evaluated for impairment

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
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-Subparagraph (g)
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-Publisher FASB
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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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