Note 4 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Impaired loans with no related allowance recorded, carrying amount
Impaired loans with no related allowance recorded, unpaid principal balance
Impaired loans with an allowance recorded, carrying amount	791	2,103
Impaired loans with an allowance recorded, unpaid principal balance	791	2,103
Impaired loans, related allowances	98	535
Impaired loans, carrying amount	791	2,103
Impaired loans, unpaid principal balance	791	2,103
Impaired loans, average recorded investment	1,688	2,170
Impaired loans, interest income recognized	55	88
Impaired loans, interest income received	54	84
Real Estate [Member]
Impaired loans, average recorded investment
Impaired loans, interest income recognized
Impaired loans, interest income received
Real Estate [Member] \| Construction, Land Development and Other Land Loans [Member]
Impaired loans with no related allowance recorded, carrying amount
Impaired loans with no related allowance recorded, unpaid principal balance
Impaired loans with an allowance recorded, carrying amount		1,361
Impaired loans with an allowance recorded, unpaid principal balance		1,361
Impaired loans, related allowances		423
Impaired loans, carrying amount		1,361
Impaired loans, unpaid principal balance		1,361
Impaired loans, average recorded investment	902	1,381
Impaired loans, interest income recognized		41
Impaired loans, interest income received		39
Real Estate [Member] \| Secured by 1-4 Family Residential Properties [Member]
Impaired loans with no related allowance recorded, carrying amount
Impaired loans with no related allowance recorded, unpaid principal balance
Impaired loans with an allowance recorded, carrying amount	187	193
Impaired loans with an allowance recorded, unpaid principal balance	187	193
Impaired loans, related allowances	5	5
Impaired loans, carrying amount	187	193
Impaired loans, unpaid principal balance	187	193
Impaired loans, average recorded investment	190	232
Impaired loans, interest income recognized	13	14
Impaired loans, interest income received	14	14
Real Estate [Member] \| Secured by Multi-family Residential Properties [Member]
Impaired loans with no related allowance recorded, carrying amount
Impaired loans with no related allowance recorded, unpaid principal balance
Impaired loans with an allowance recorded, carrying amount
Impaired loans with an allowance recorded, unpaid principal balance
Impaired loans, related allowances
Impaired loans, carrying amount
Impaired loans, unpaid principal balance
Impaired loans, average recorded investment
Impaired loans, interest income recognized
Impaired loans, interest income received
Real Estate [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Impaired loans with no related allowance recorded, carrying amount
Impaired loans with no related allowance recorded, unpaid principal balance
Impaired loans with an allowance recorded, carrying amount	532	549
Impaired loans with an allowance recorded, unpaid principal balance	532	549
Impaired loans, related allowances	21	107
Impaired loans, carrying amount	532	549
Impaired loans, unpaid principal balance	532	549
Impaired loans, average recorded investment	537	557
Impaired loans, interest income recognized	35	33
Impaired loans, interest income received	35	31
Commercial and Industrial Loans [Member]
Impaired loans with no related allowance recorded, carrying amount
Impaired loans with no related allowance recorded, unpaid principal balance
Impaired loans with an allowance recorded, carrying amount	72
Impaired loans with an allowance recorded, unpaid principal balance	72
Impaired loans, related allowances	72
Impaired loans, carrying amount	72
Impaired loans, unpaid principal balance	72
Impaired loans, average recorded investment	59
Impaired loans, interest income recognized	7
Impaired loans, interest income received	$ 5

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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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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

+ 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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