Note 9 - Allowance for Loan Losses and Credit Quality Information - Impaired Loans and Related Allowances (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Related allowance	$ 647		$ 725
Recorded investment	3,639		3,851
Unpaid principal balance	4,210		4,422
Average recorded investment	3,748	$ 3,595
Interest income recognized	42	43
Residential Portfolio Segment [Member]
Recorded investment, with no related allowance	583		544
Unpaid principal balance, with no related allowance	602		563
Recorded investment, with related allowance	420		430
Unpaid principal balance, with related allowance	420		430
Related allowance	46		62
Recorded investment	1,003		974
Unpaid principal balance	1,022		993
Average recorded investment, with no related allowance	564	448
Interest income recognized, with no related allowance	5	4
Average recorded investment, with related allowance	425	789
Interest income recognized, with related allowance	6	3
Average recorded investment	989	1,237
Interest income recognized	11	7
Commercial Real Estate Portfolio Segment [Member]
Related allowance	443		451
Commercial Real Estate Portfolio Segment [Member] \| Commercial Real Estate Other [Member]
Recorded investment, with no related allowance	557		0
Unpaid principal balance, with no related allowance	557		0
Recorded investment, with related allowance	967		982
Unpaid principal balance, with related allowance	967		982
Related allowance	437		435
Recorded investment	1,524		982
Unpaid principal balance	1,524		982
Average recorded investment, with no related allowance	279	25
Interest income recognized, with no related allowance	2	30
Average recorded investment, with related allowance	975	1,069
Interest income recognized, with related allowance	20	0
Average recorded investment	1,254	1,094
Interest income recognized	22	30
Commercial Real Estate Portfolio Segment [Member] \| Real Estate Loan [Member]
Recorded investment, with related allowance	179		184
Unpaid principal balance, with related allowance	179		184
Related allowance	6		16
Recorded investment	179		184
Unpaid principal balance	179		184
Average recorded investment, with related allowance	182	200
Interest income recognized, with related allowance	0	0
Interest income recognized	0	0
Consumer Portfolio Segment [Member]
Recorded investment, with no related allowance	606		781
Unpaid principal balance, with no related allowance	606		781
Recorded investment, with related allowance	196		195
Unpaid principal balance, with related allowance	196		195
Related allowance	120		119
Recorded investment	802		976
Unpaid principal balance	802		976
Average recorded investment, with no related allowance	694	449
Interest income recognized, with no related allowance	5	2
Average recorded investment, with related allowance	196	290
Interest income recognized, with related allowance	2	3
Average recorded investment	890	739
Interest income recognized	7	5
Commercial Portfolio Segment [Member]
Recorded investment, with related allowance	131		735
Unpaid principal balance, with related allowance	683		1,287
Related allowance	38		93
Recorded investment	131		735
Unpaid principal balance	683		$ 1,287
Average recorded investment, with related allowance	433	325
Interest income recognized, with related allowance	2	1
Average recorded investment	433	325
Interest income recognized	$ 2	$ 1

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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- Definition

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+ References

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)
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+ References

Reference 1: 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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

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