Note 4 - Allowance for Loan Losses - Segregated by Impairment Methodology (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Ending Allowance Balance Individually Evaluated for Impairment	$ 3,439		$ 2,531
Ending Allowance Balance Collectively Evaluated for Impairment	5,425		7,018
Ending Allowance Balance Total	8,864	$ 8,923	9,549	$ 8,604
Ending Loan Balance Individually Evaluated for Impairment	24,086		22,115
Ending Loan Balance Collectively Evaluated for Impairment	736,255		732,146
Ending Loan Balance Total	760,341	754,283	754,261
Commercial [Member] \| Commercial and Agricultural Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment			4
Ending Allowance Balance Collectively Evaluated for Impairment	403		550
Ending Allowance Balance Total	403	456	554	855
Ending Loan Balance Individually Evaluated for Impairment			37
Ending Loan Balance Collectively Evaluated for Impairment	44,925		45,078
Ending Loan Balance Total	44,925	47,025	45,115
Commercial [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment	3,051		1,940
Ending Allowance Balance Collectively Evaluated for Impairment	2,868		3,306
Ending Allowance Balance Total	5,919	5,751	5,246	3,851
Ending Loan Balance Individually Evaluated for Impairment	19,865		16,918
Ending Loan Balance Collectively Evaluated for Impairment	339,278		330,454
Ending Loan Balance Total	359,143	349,090	347,372
Agricultural [Member] \| Commercial and Agricultural Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment
Ending Allowance Balance Collectively Evaluated for Impairment	189		192
Ending Allowance Balance Total	189	168	192	203
Ending Loan Balance Individually Evaluated for Impairment	5
Ending Loan Balance Collectively Evaluated for Impairment	19,301		18,562
Ending Loan Balance Total	19,306	17,080	18,562
Commercial Construction [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment	21		24
Ending Allowance Balance Collectively Evaluated for Impairment	281		786
Ending Allowance Balance Total	302	323	810	691
Ending Loan Balance Individually Evaluated for Impairment	72		389
Ending Loan Balance Collectively Evaluated for Impairment	30,468		35,581
Ending Loan Balance Total	30,540	30,358	35,970
Residential Construction [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment
Ending Allowance Balance Collectively Evaluated for Impairment	10		20
Ending Allowance Balance Total	10	13	20	20
Ending Loan Balance Individually Evaluated for Impairment
Ending Loan Balance Collectively Evaluated for Impairment	9,367		9,849
Ending Loan Balance Total	9,367	11,830	9,849
Residential [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment	340		528
Ending Allowance Balance Collectively Evaluated for Impairment	896		1,277
Ending Allowance Balance Total	1,236	1,396	1,805	1,990
Ending Loan Balance Individually Evaluated for Impairment	3,102		3,370
Ending Loan Balance Collectively Evaluated for Impairment	192,180		192,309
Ending Loan Balance Total	195,282	195,580	195,679
Farmland [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment	27		35
Ending Allowance Balance Collectively Evaluated for Impairment	682		768
Ending Allowance Balance Total	709	722	803	912
Ending Loan Balance Individually Evaluated for Impairment	1,042		1,401
Ending Loan Balance Collectively Evaluated for Impairment	63,828		64,884
Ending Loan Balance Total	64,870	66,877	66,285
Consumer [Member] \| Consumer and Other Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment
Ending Allowance Balance Collectively Evaluated for Impairment	81		101
Ending Allowance Balance Total	81	80	101	63
Ending Loan Balance Individually Evaluated for Impairment
Ending Loan Balance Collectively Evaluated for Impairment	19,188		19,661
Ending Loan Balance Total	19,188	19,695	19,661
Other [Member] \| Consumer and Other Portfolio Segment [Member]
Ending Allowance Balance Individually Evaluated for Impairment
Ending Allowance Balance Collectively Evaluated for Impairment	15		18
Ending Allowance Balance Total	15	14	18	$ 19
Ending Loan Balance Individually Evaluated for Impairment
Ending Loan Balance Collectively Evaluated for Impairment	17,720		15,768
Ending Loan Balance Total	$ 17,720	$ 16,748	$ 15,768

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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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.

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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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