Note 4 - Loans and Allowance for Credit Losses - Loans Individually Evaluated for Impairment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2019
Loans with no related allowance recorded, recorded investment		$ 3,468
Loans with no related allowance recorded, unpaid principal balance		3,926
Loans with no related allowance recorded, average recorded investment	$ 2,941
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		8,062
Loans with an allowance recorded, unpaid principal balance		8,062
Related allowance		1,163
Loans with an allowance recorded, average recorded investment	41
Loans with an allowance recorded, interest income recognized	1
Commercial and Industrial Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment		174
Loans with no related allowance recorded, unpaid principal balance		174
Loans with no related allowance recorded, average recorded investment	192
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		8,049
Loans with an allowance recorded, unpaid principal balance		8,049
Related allowance		1,150
Loans with an allowance recorded, average recorded investment	27
Loans with an allowance recorded, interest income recognized	1
Recorded investment		8,223
Unpaid principal balance		8,223
Average recorded investment	219
Interest income recognized	1
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment		0
Loans with no related allowance recorded, unpaid principal balance		0
Loans with no related allowance recorded, average recorded investment	159
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		0
Loans with an allowance recorded, unpaid principal balance		0
Related allowance		0
Loans with an allowance recorded, average recorded investment	159
Loans with an allowance recorded, interest income recognized	0
Undevelopment Land Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment		0
Loans with no related allowance recorded, unpaid principal balance		0
Loans with no related allowance recorded, average recorded investment	237
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		0
Loans with an allowance recorded, unpaid principal balance		0
Related allowance		0
Loans with an allowance recorded, average recorded investment	237
Loans with an allowance recorded, interest income recognized	0
Real Estate Mortgage Portfolio Segment [Member]
Loans with no related allowance recorded, recorded investment		3,294
Loans with no related allowance recorded, unpaid principal balance		3,752
Loans with no related allowance recorded, average recorded investment	2,353
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		13
Loans with an allowance recorded, unpaid principal balance		13
Related allowance		13
Loans with an allowance recorded, average recorded investment	14
Loans with an allowance recorded, interest income recognized	0
Recorded investment		3,307
Unpaid principal balance		3,765
Average recorded investment	2,367
Interest income recognized	0
Real Estate Mortgage Portfolio Segment [Member] \| Commercial Investment [Member]
Loans with no related allowance recorded, recorded investment		741
Loans with no related allowance recorded, unpaid principal balance		741
Loans with no related allowance recorded, average recorded investment	227
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		741
Loans with an allowance recorded, unpaid principal balance		741
Related allowance		0
Loans with an allowance recorded, average recorded investment	227
Loans with an allowance recorded, interest income recognized	0
Real Estate Mortgage Portfolio Segment [Member] \| Owner Occupied Commercial [Member]
Loans with no related allowance recorded, recorded investment		2,278
Loans with no related allowance recorded, unpaid principal balance		2,736
Loans with no related allowance recorded, average recorded investment	1,026
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		2,278
Loans with an allowance recorded, unpaid principal balance		2,736
Related allowance		0
Loans with an allowance recorded, average recorded investment	1,026
Loans with an allowance recorded, interest income recognized	0
Real Estate Mortgage Portfolio Segment [Member] \| One to Four Family Residential [Member]
Loans with no related allowance recorded, recorded investment		124
Loans with no related allowance recorded, unpaid principal balance		124
Loans with no related allowance recorded, average recorded investment	801
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		13
Loans with an allowance recorded, unpaid principal balance		13
Related allowance		13
Loans with an allowance recorded, average recorded investment	14
Loans with an allowance recorded, interest income recognized	0
Recorded investment		137
Unpaid principal balance		137
Average recorded investment	815
Interest income recognized	0
Real Estate Mortgage Portfolio Segment [Member] \| Home Equity Junior Lien [Member]
Loans with no related allowance recorded, recorded investment		151
Loans with no related allowance recorded, unpaid principal balance		151
Loans with no related allowance recorded, average recorded investment	299
Loans with no related allowance recorded, interest income recognized	0
Loans with an allowance recorded, recorded investment		151
Loans with an allowance recorded, unpaid principal balance		151
Related allowance		0
Loans with an allowance recorded, average recorded investment	299
Loans with an allowance recorded, interest income recognized	0
Real Estate Mortgage Portfolio Segment [Member] \| Home Equity First Lien [Member]
Loans with no related allowance recorded, recorded investment		0
Loans with no related allowance recorded, unpaid principal balance		$ 0
Loans with no related allowance recorded, average recorded investment	0
Loans with no related allowance recorded, interest income recognized	$ 0

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=121611835&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=121611835&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
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

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