Note 4 - Credit Quality - Average Annual Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Impaired loans with no related allowance, interest income recognized	$ 291	$ 305	$ 606	$ 754
Impaired loans with no related allowance, average recorded investment	31,306	29,803	26,215	29,170
Impaired loans with a related allowance, interest income recognized	82	74	231	324
Impaired loans with a related allowance, average recorded investment	8,393	9,470	8,264	10,342
Total impaired loans, interest income recognized	373	379	837	1,078
Total impaired loans, average recorded investment	39,699	39,273	34,479	39,512
Commercial Portfolio Segment [Member] \| Construction, Development and Other Land [Member]
Impaired loans with no related allowance, interest income recognized	32	22	32	22
Impaired loans with no related allowance, average recorded investment	907	600	309	447
Impaired loans with a related allowance, interest income recognized
Impaired loans with a related allowance, average recorded investment			143
Commercial Portfolio Segment [Member] \| Commercial and Industrial [Member]
Impaired loans with no related allowance, interest income recognized	5	6	8	10
Impaired loans with no related allowance, average recorded investment	754	1,029	468	738
Impaired loans with a related allowance, interest income recognized	50		103
Impaired loans with a related allowance, average recorded investment	2,516		1,727
Commercial Portfolio Segment [Member] \| Multi-family Residential [Member]
Impaired loans with no related allowance, interest income recognized		15	3	15
Impaired loans with no related allowance, average recorded investment	509	562	474	309
Commercial Portfolio Segment [Member] \| Single Family Non-owner Occupied [Member]
Impaired loans with no related allowance, interest income recognized	11	91	88	107
Impaired loans with no related allowance, average recorded investment	3,304	3,498	3,313	3,035
Impaired loans with a related allowance, interest income recognized	8	5	21	18
Impaired loans with a related allowance, average recorded investment	778	682	488	572
Commercial Portfolio Segment [Member] \| Non-farm, Non-residential [Member]
Impaired loans with no related allowance, interest income recognized	68	65	93	307
Impaired loans with no related allowance, average recorded investment	5,244	8,930	3,766	10,186
Impaired loans with a related allowance, interest income recognized		45	15	215
Impaired loans with a related allowance, average recorded investment	872	4,658	964	5,108
Commercial Portfolio Segment [Member] \| Agricultural [Member]
Impaired loans with no related allowance, interest income recognized	4		4
Impaired loans with no related allowance, average recorded investment	127		127
Commercial Portfolio Segment [Member] \| Farmland [Member]
Impaired loans with no related allowance, interest income recognized	17	5	17	9
Impaired loans with no related allowance, average recorded investment	1,003	204	1,004	186
Impaired loans with a related allowance, interest income recognized
Impaired loans with a related allowance, average recorded investment	413		275
Consumer Real Estate Portfolio Segment [Member] \| Home Equity Lines [Member]
Impaired loans with no related allowance, interest income recognized	15	6	35	21
Impaired loans with no related allowance, average recorded investment	1,683	1,157	1,259	1,318
Impaired loans with a related allowance, interest income recognized
Impaired loans with a related allowance, average recorded investment			139
Consumer Real Estate Portfolio Segment [Member] \| Single Family Owner Occupied [Member]
Impaired loans with no related allowance, interest income recognized	137	91	317	254
Impaired loans with no related allowance, average recorded investment	17,478	13,175	15,209	12,436
Impaired loans with a related allowance, interest income recognized	24	24	92	91
Impaired loans with a related allowance, average recorded investment	3,814	4,130	4,527	4,547
Consumer Real Estate Portfolio Segment [Member] \| Owner Occupied Construction [Member]
Impaired loans with no related allowance, interest income recognized	1	2	6	7
Impaired loans with no related allowance, average recorded investment	235	585	234	470
Impaired loans with a related allowance, interest income recognized
Impaired loans with a related allowance, average recorded investment			1	115
Consumer and Other Portfolio Segment [Member] \| Consumer Loan [Member]
Impaired loans with no related allowance, interest income recognized	1	2	3	2
Impaired loans with no related allowance, average recorded investment	$ 62	$ 63	$ 52	$ 45

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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