Note 3 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Recorded investment with no allowance	$ 3,004		$ 3,168
Unpaid principal balance with no allowance	3,190		3,338
Average recorded investment with no allowance	3,088	$ 2,564
Interest income recognized with no allowance	17	18
Recorded investment with allowance	291
Unpaid principal balance with allowance	294
Related allowance	9		0
Average recorded investment with allowance	146	184
Interest income recognized with allowance	0	0
Recorded investment	3,295		3,168
Unpaid principal balance	3,484		3,338
Average recorded investment	3,234	2,748
Interest income recognized	17	18
Real Estate Mortgage Portfolio Segment [Member] \| Residential Loan [Member]
Recorded investment with no allowance	1,879		1,728
Unpaid principal balance with no allowance	2,058		1,902
Average recorded investment with no allowance	1,804	1,700
Interest income recognized with no allowance	5	6
Recorded investment with allowance	0		0
Unpaid principal balance with allowance	0		0
Related allowance	0		0
Average recorded investment with allowance	0	184
Interest income recognized with allowance	0	0
Recorded investment	1,879		1,728
Unpaid principal balance	2,058		1,902
Average recorded investment	1,804	1,884
Interest income recognized	5	6
Real Estate Mortgage Portfolio Segment [Member] \| Land Loan [Member]
Recorded investment with no allowance	100		97
Unpaid principal balance with no allowance	101		97
Average recorded investment with no allowance	99	115
Interest income recognized with no allowance	0	0
Recorded investment with allowance	0		0
Unpaid principal balance with allowance	0		0
Related allowance	0		0
Average recorded investment with allowance	0	0
Interest income recognized with allowance	0	0
Recorded investment	100		97
Unpaid principal balance	101		97
Average recorded investment	99	115
Interest income recognized	0	0
Real Estate Mortgage Portfolio Segment [Member] \| Construction Loans [Member]
Recorded investment with no allowance	0		0
Unpaid principal balance with no allowance	0		0
Average recorded investment with no allowance	0	0
Interest income recognized with no allowance	0	0
Recorded investment with allowance	0		0
Unpaid principal balance with allowance	0		0
Related allowance	0		0
Average recorded investment with allowance	0	0
Interest income recognized with allowance	0	0
Recorded investment	0		0
Unpaid principal balance	0		0
Average recorded investment	0	0
Interest income recognized	0	0
Real Estate Mortgage Portfolio Segment [Member] \| Commercial Real Estate Loan [Member]
Recorded investment with no allowance	760		779
Unpaid principal balance with no allowance	768		784
Average recorded investment with no allowance	770	400
Interest income recognized with no allowance	9	9
Recorded investment with allowance	0		0
Unpaid principal balance with allowance	0		0
Related allowance	0		0
Average recorded investment with allowance	0	0
Interest income recognized with allowance	0	0
Recorded investment	760		779
Unpaid principal balance	768		784
Average recorded investment	770	400
Interest income recognized	9	9
Commercial Portfolio Segment [Member]
Recorded investment with no allowance	201		211
Unpaid principal balance with no allowance	201		210
Average recorded investment with no allowance	206	248
Interest income recognized with no allowance	2	2
Recorded investment with allowance	0		0
Unpaid principal balance with allowance	0		0
Related allowance	0		0
Average recorded investment with allowance	0	0
Interest income recognized with allowance	0	0
Recorded investment	201		211
Unpaid principal balance	201		210
Average recorded investment	206	248
Interest income recognized	2	2
Consumer Portfolio Segment [Member] \| Home Equity and Second Mortgage [Member]
Recorded investment with no allowance	64		353
Unpaid principal balance with no allowance	62		345
Average recorded investment with no allowance	209	56
Interest income recognized with no allowance	1	1
Recorded investment with allowance	291		0
Unpaid principal balance with allowance	294		0
Related allowance	9		0
Average recorded investment with allowance	146	0
Interest income recognized with allowance	0	0
Recorded investment	355		353
Unpaid principal balance	356		345
Average recorded investment	355	56
Interest income recognized	1	1
Consumer Portfolio Segment [Member] \| All Other Consumer Excluding Home Equity and Second Mortgage [Member]
Recorded investment with no allowance	0		0
Unpaid principal balance with no allowance	0		0
Average recorded investment with no allowance	0	45
Interest income recognized with no allowance	0	0
Recorded investment with allowance	0		0
Unpaid principal balance with allowance	0		0
Related allowance	0		0
Average recorded investment with allowance	0	0
Interest income recognized with allowance	0	0
Recorded investment	0		0
Unpaid principal balance	0		$ 0
Average recorded investment	0	45
Interest income recognized	$ 0	$ 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
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

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