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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Impaired loans with no related allowance, interest income recognized	$ 57	$ 291	$ 408	$ 606
Impaired loans with no related allowance, average recorded investment	28,391	31,306	28,394	26,215
Impaired loans with a related allowance, interest income recognized	36	82	136	231
Impaired loans with a related allowance, average recorded investment	6,869	8,393	8,001	8,264
Total impaired loans, interest income recognized	93	373	544	837
Total impaired loans, average recorded investment	35,260	39,699	36,395	34,479
Commercial Portfolio Segment [Member] \| Construction, Development and Other Land [Member]
Impaired loans with no related allowance, interest income recognized		32	14	32
Impaired loans with no related allowance, average recorded investment	910	907	950	309
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	3	5	6	8
Impaired loans with no related allowance, average recorded investment	311	754	378	468
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	5		15	3
Impaired loans with no related allowance, average recorded investment	1,402	509	832	474
Impaired loans with a related allowance, interest income recognized
Impaired loans with a related allowance, average recorded investment	541		271
Commercial Portfolio Segment [Member] \| Single Family Non-owner Occupied [Member]
Impaired loans with no related allowance, interest income recognized	8	11	56	88
Impaired loans with no related allowance, average recorded investment	2,529	3,304	2,599	3,313
Impaired loans with a related allowance, interest income recognized		8	7	21
Impaired loans with a related allowance, average recorded investment	849	778	644	488
Commercial Portfolio Segment [Member] \| Non-farm, Non-residential [Member]
Impaired loans with no related allowance, interest income recognized		68	39	93
Impaired loans with no related allowance, average recorded investment	3,926	5,244	5,028	3,766
Impaired loans with a related allowance, interest income recognized				15
Impaired loans with a related allowance, average recorded investment		872	770	964
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	103	127	187	127
Commercial Portfolio Segment [Member] \| Farmland [Member]
Impaired loans with no related allowance, interest income recognized	23	17	38	17
Impaired loans with no related allowance, average recorded investment	1,425	1,003	1,066	1,004
Impaired loans with a related allowance, interest income recognized
Impaired loans with a related allowance, average recorded investment	413	413	409	275
Consumer Real Estate Portfolio Segment [Member] \| Home Equity Lines [Member]
Impaired loans with no related allowance, interest income recognized	3	15	20	35
Impaired loans with no related allowance, average recorded investment	1,514	1,683	1,719	1,259
Impaired loans with a related allowance, interest income recognized	1		3
Impaired loans with a related allowance, average recorded investment	67		69	139
Consumer Real Estate Portfolio Segment [Member] \| Single Family Owner Occupied [Member]
Impaired loans with no related allowance, interest income recognized	15	137	208	317
Impaired loans with no related allowance, average recorded investment	15,832	17,478	15,222	15,209
Impaired loans with a related allowance, interest income recognized	35	24	126	92
Impaired loans with a related allowance, average recorded investment	4,999	3,814	5,838	4,527
Consumer Real Estate Portfolio Segment [Member] \| Owner Occupied Construction [Member]
Impaired loans with no related allowance, interest income recognized		1	6	6
Impaired loans with no related allowance, average recorded investment	229	235	249	234
Impaired loans with a related allowance, interest income recognized
Impaired loans with a related allowance, average recorded investment				1
Consumer and Other Portfolio Segment [Member] \| Consumer Loans [Member]
Impaired loans with no related allowance, interest income recognized		1	6	3
Impaired loans with no related allowance, average recorded investment	$ 210	$ 62	$ 164	$ 52

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://fasb.org/us-gaap/role/ref/legacyRef
-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://fasb.org/us-gaap/role/ref/legacyRef
-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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