Note 6 - Loans and the Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Recorded investment, with an allowance recorded	$ 1,213	$ 1,436
Unpaid principal balance, with an allowance recorded	1,388	1,543
Related allowance	373	536
Average recorded investment, with an allowance recorded	1,086	1,830
Recorded investment, with no allowance recorded	11,292	12,013
Unpaid principal balance, with no allowance recorded	13,783	14,459
Average recorded investment, with no allowance recorded	14,505	11,775
Recorded investment	12,505	13,449
Unpaid principal balance	15,171	16,002
Average recorded investment	15,591	13,605
Commercial Real Estate Portfolio Segment [Member] \| Construction and Land [Member]
Recorded investment, with an allowance recorded	0	90
Unpaid principal balance, with an allowance recorded	0	90
Related allowance	0	36
Average recorded investment, with an allowance recorded	30	74
Recorded investment, with no allowance recorded	7	3
Unpaid principal balance, with no allowance recorded	35	9
Average recorded investment, with no allowance recorded	12	44
Recorded investment	7	93
Unpaid principal balance	35	99
Average recorded investment	42	118
Commercial Real Estate Portfolio Segment [Member] \| Farmland [Member]
Recorded investment, with an allowance recorded	0	0
Unpaid principal balance, with an allowance recorded	0	0
Related allowance	0	0
Average recorded investment, with an allowance recorded	0	0
Recorded investment, with no allowance recorded	0	0
Unpaid principal balance, with no allowance recorded	0	0
Average recorded investment, with no allowance recorded	0	0
Recorded investment	0	0
Unpaid principal balance	0	0
Average recorded investment	0	0
Commercial Real Estate Portfolio Segment [Member] \| Nonfarm Nonresidential [Member]
Recorded investment, with an allowance recorded	463	316
Unpaid principal balance, with an allowance recorded	509	341
Related allowance	54	46
Average recorded investment, with an allowance recorded	339	462
Recorded investment, with no allowance recorded	3,660	5,515
Unpaid principal balance, with no allowance recorded	3,728	5,653
Average recorded investment, with no allowance recorded	5,764	3,402
Recorded investment	4,123	5,831
Unpaid principal balance	4,237	5,994
Average recorded investment	6,103	3,864
Residential Portfolio Segment [Member] \| Real Estate Residential One- to Four-Family [Member]
Recorded investment, with an allowance recorded	372	491
Unpaid principal balance, with an allowance recorded	452	540
Related allowance	105	125
Average recorded investment, with an allowance recorded	289	787
Recorded investment, with no allowance recorded	2,523	2,325
Unpaid principal balance, with no allowance recorded	3,018	2,744
Average recorded investment, with no allowance recorded	2,728	2,188
Recorded investment	2,895	2,816
Unpaid principal balance	3,470	3,284
Average recorded investment	3,017	2,975
Residential Portfolio Segment [Member] \| Multi-family Residential [Member]
Recorded investment, with an allowance recorded	0	0
Unpaid principal balance, with an allowance recorded	0	0
Related allowance	0	0
Average recorded investment, with an allowance recorded	0	0
Recorded investment, with no allowance recorded	0	0
Unpaid principal balance, with no allowance recorded	0	0
Average recorded investment, with no allowance recorded	0	0
Recorded investment	0	0
Unpaid principal balance	0	0
Average recorded investment	0	0
Commercial Portfolio Segment [Member]
Recorded investment, with an allowance recorded	378	539
Unpaid principal balance, with an allowance recorded	427	572
Related allowance	214	329
Average recorded investment, with an allowance recorded	428	502
Recorded investment, with no allowance recorded	4,999	3,729
Unpaid principal balance, with no allowance recorded	6,857	5,581
Average recorded investment, with no allowance recorded	5,689	5,898
Recorded investment	5,377	4,268
Unpaid principal balance	7,284	6,153
Average recorded investment	6,117	6,400
Consumer Portfolio Segment [Member]
Recorded investment, with an allowance recorded	0	0
Unpaid principal balance, with an allowance recorded	0	0
Related allowance	0	0
Average recorded investment, with an allowance recorded	0	5
Recorded investment, with no allowance recorded	103	441
Unpaid principal balance, with no allowance recorded	145	472
Average recorded investment, with no allowance recorded	312	243
Recorded investment	103	441
Unpaid principal balance	145	472
Average recorded investment	$ 312	$ 248

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
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-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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