Note 9 - Allowance for Loan Losses and Credit Quality Information - Impaired Loans and Related Allowances (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related allowance	$ 286		$ 286		$ 238
Recorded investment	1,871		1,871		3,126
Unpaid principal balance	1,890		1,890		4,346
Specific reserves	286		286		238
Average recorded investment	1,860	$ 3,068	2,452	$ 3,408
Interest income recognized	3	10	19	71
Residential Portfolio Segment [Member]
Recorded investment, with no related allowance	356		356		740
Unpaid principal balance, with no related allowance	375		375		759
Recorded investment, with related allowance	89		89		117
Unpaid principal balance, with related allowance	89		89		117
Related allowance	38		38		29
Recorded investment	445		445		857
Unpaid principal balance	464		464		876
Specific reserves	38		38		29
Average recorded investment, with no related allowance	390	606	564	585
Interest income recognized, with no related allowance	0	6	4	23
Average recorded investment, with related allowance	122	121	119	273
Interest income recognized, with related allowance	0	0	0	0
Average recorded investment	512	727	683	858
Interest income recognized	0	6	4	23
Commercial Real Estate Portfolio Segment [Member]
Related allowance	152		152		95
Specific reserves	152		152		95
Commercial Real Estate Portfolio Segment [Member] \| Real Estate Loan [Member]
Recorded investment, with no related allowance	0		0		932
Unpaid principal balance, with no related allowance	0		0		1,582
Recorded investment, with related allowance	325		325		166
Unpaid principal balance, with related allowance	325		325		166
Related allowance	17		17		5
Recorded investment	325		325		1,098
Unpaid principal balance	325		325		1,748
Specific reserves	17		17		5
Average recorded investment, with no related allowance	78	985	540	493
Interest income recognized, with no related allowance	0	0	0	33
Average recorded investment, with related allowance	163	173	123	177
Interest income recognized, with related allowance	0	0	7	0
Average recorded investment	241	1,158	663	670
Interest income recognized	0	0	7	33
Commercial Real Estate Portfolio Segment [Member] \| Commercial Real Estate Other [Member]
Recorded investment, with no related allowance	192		192		211
Unpaid principal balance, with no related allowance	192		192		211
Recorded investment, with related allowance	167		167		175
Unpaid principal balance, with related allowance	167		167		175
Related allowance	135		135		90
Recorded investment	359		359		386
Unpaid principal balance	359		359		386
Specific reserves	135		135		90
Average recorded investment, with no related allowance	193	401	199	340
Interest income recognized, with no related allowance	0	0	0	2
Average recorded investment, with related allowance	168	0	163	487
Interest income recognized, with related allowance	0	0	0	0
Average recorded investment	361	401	362	827
Interest income recognized	0	0	0	2
Consumer Portfolio Segment [Member]
Recorded investment, with no related allowance	592		592		574
Unpaid principal balance, with no related allowance	592		592		574
Recorded investment, with related allowance	132		132		176
Unpaid principal balance, with related allowance	132		132		176
Related allowance	88		88		100
Recorded investment	724		724		750
Unpaid principal balance	724		724		750
Specific reserves	88		88		100
Average recorded investment, with no related allowance	610	586	577	640
Interest income recognized, with no related allowance	0	3	6	9
Average recorded investment, with related allowance	114	142	138	169
Interest income recognized, with related allowance	3	0	1	2
Average recorded investment	724	728	715	809
Interest income recognized	3	3	7	11
Commercial Portfolio Segment [Member]
Recorded investment, with related allowance	18		18		35
Unpaid principal balance, with related allowance	18		18		586
Related allowance	8		8		14
Recorded investment	18		18		35
Unpaid principal balance	18		18		586
Specific reserves	8		8		$ 14
Average recorded investment, with no related allowance		4		2
Interest income recognized, with no related allowance		0		0
Average recorded investment, with related allowance	22	50	29	242
Interest income recognized, with related allowance	0	1	1	2
Average recorded investment	22	54	29	244
Interest income recognized	$ 0	$ 1	$ 1	$ 2

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=123577603&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Section 50
-Paragraph 17
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