Note 5 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Impaired loans with no related allowance recorded, carrying amount	$ 1,666	$ 708
Impaired loans with no related allowance recorded, unpaid principal balance	1,666	708
Impaired loans with an allowance recorded, carrying amount	548	831
Impaired loans with an allowance recorded, unpaid principal balance	548	831
Impaired loans, related allowances	196	166
Impaired loans, carrying amount	2,214	1,539
Impaired loans, unpaid principal balance	2,214	1,539
Impaired loans, average recorded investment	1,700	1,460
Impaired loans, interest income recognized	30	65
Impaired loans, interest income received	23	67
Real Estate [Member] \| Construction, Land Development and Other Land Loans [Member]
Impaired loans with no related allowance recorded, carrying amount	73	73
Impaired loans with no related allowance recorded, unpaid principal balance	73	73
Impaired loans with an allowance recorded, carrying amount	421	153
Impaired loans with an allowance recorded, unpaid principal balance	421	153
Impaired loans, related allowances	98	28
Impaired loans, carrying amount	494	226
Impaired loans, unpaid principal balance	494	226
Impaired loans, average recorded investment	90	70
Impaired loans, interest income recognized	4	8
Impaired loans, interest income received	3	8
Real Estate [Member] \| Secured by 1-4 Family Residential Properties [Member]
Impaired loans with no related allowance recorded, carrying amount	1,083	635
Impaired loans with no related allowance recorded, unpaid principal balance	1,083	635
Impaired loans with an allowance recorded, carrying amount	23	57
Impaired loans with an allowance recorded, unpaid principal balance	23	57
Impaired loans, related allowances	16	50
Impaired loans, carrying amount	1,106	692
Impaired loans, unpaid principal balance	1,106	692
Impaired loans, average recorded investment	765	794
Impaired loans, interest income recognized	14	16
Impaired loans, interest income received	10	16
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	510
Impaired loans with no related allowance recorded, unpaid principal balance	510
Impaired loans with an allowance recorded, carrying amount		511
Impaired loans with an allowance recorded, unpaid principal balance		511
Impaired loans, related allowances		1
Impaired loans, carrying amount	510	511
Impaired loans, unpaid principal balance	510	511
Impaired loans, average recorded investment	734	523
Impaired loans, interest income recognized	9	34
Impaired loans, interest income received	7	35
Real Estate [Member] \| Other Real Estate Loans [Member]
Impaired loans, average recorded investment		1
Impaired loans, interest income recognized
Impaired loans, interest income received
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	66	67
Impaired loans with an allowance recorded, unpaid principal balance	66	67
Impaired loans, related allowances	66	67
Impaired loans, carrying amount	66	67
Impaired loans, unpaid principal balance	66	67
Impaired loans, average recorded investment	66	57
Impaired loans, interest income recognized	2	4
Impaired loans, interest income received	2	5
Consumer Portfolio Segment [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	38	43
Impaired loans with an allowance recorded, unpaid principal balance	38	43
Impaired loans, related allowances	16	20
Impaired loans, carrying amount	38	43
Impaired loans, unpaid principal balance	38	43
Impaired loans, average recorded investment	45	15
Impaired loans, interest income recognized	1	3
Impaired loans, interest income received	$ 1	$ 3

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=118936363&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=118936363&loc=d3e5258-111524

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524

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