Note 6 - Loans and the Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Recorded investment, with an allowance recorded	$ 2,081	$ 1,539
Unpaid principal balance, with an allowance recorded	2,207	1,583
Related allowance	881	887
Average recorded investment, with an allowance recorded	1,886	2,322
Recorded investment, with no allowance recorded	14,512	10,470
Unpaid principal balance, with no allowance recorded	16,252	12,145
Average recorded investment, with no allowance recorded	11,117	10,873
Recorded investment	16,593	12,009
Unpaid principal balance	18,459	13,728
Average recorded investment	13,003	13,195
Commercial Real Estate Portfolio Segment [Member] \| Construction and Land [Member]
Recorded investment, with an allowance recorded	89	0
Unpaid principal balance, with an allowance recorded	89	0
Related allowance	22	0
Average recorded investment, with an allowance recorded	70	655
Recorded investment, with no allowance recorded	9	143
Unpaid principal balance, with no allowance recorded	16	152
Average recorded investment, with no allowance recorded	58	124
Recorded investment	98	143
Unpaid principal balance	105	152
Average recorded investment	128	779
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	679	368
Unpaid principal balance, with an allowance recorded	701	368
Related allowance	111	98
Average recorded investment, with an allowance recorded	509	31
Recorded investment, with no allowance recorded	5,400	705
Unpaid principal balance, with no allowance recorded	5,494	729
Average recorded investment, with no allowance recorded	2,686	3,730
Recorded investment	6,079	1,073
Unpaid principal balance	6,195	1,097
Average recorded investment	3,195	3,761
Residential Portfolio Segment [Member] \| Real Estate Residential One- to Four-Family [Member]
Recorded investment, with an allowance recorded	751	440
Unpaid principal balance, with an allowance recorded	830	470
Related allowance	340	252
Average recorded investment, with an allowance recorded	815	372
Recorded investment, with no allowance recorded	2,087	2,823
Unpaid principal balance, with no allowance recorded	2,444	3,276
Average recorded investment, with no allowance recorded	2,222	3,296
Recorded investment	2,838	3,263
Unpaid principal balance	3,274	3,746
Average recorded investment	3,037	3,668
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	562	695
Unpaid principal balance, with an allowance recorded	587	709
Related allowance	408	501
Average recorded investment, with an allowance recorded	485	1,252
Recorded investment, with no allowance recorded	6,642	6,637
Unpaid principal balance, with no allowance recorded	7,893	7,826
Average recorded investment, with no allowance recorded	5,975	3,680
Recorded investment	7,204	7,332
Unpaid principal balance	8,480	8,535
Average recorded investment	6,460	4,932
Consumer Portfolio Segment [Member]
Recorded investment, with an allowance recorded	0	36
Unpaid principal balance, with an allowance recorded	0	36
Related allowance	0	36
Average recorded investment, with an allowance recorded	7	12
Recorded investment, with no allowance recorded	374	162
Unpaid principal balance, with no allowance recorded	405	162
Average recorded investment, with no allowance recorded	176	43
Recorded investment	374	198
Unpaid principal balance	405	198
Average recorded investment	$ 183	$ 55

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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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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Reference 1: 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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-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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