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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related allowance	$ 116		$ 116		$ 725
Recorded investment	2,997		2,997		3,851
Unpaid principal balance	4,298		4,298		4,422
Average recorded investment	3,068	$ 3,434	3,408	$ 3,513
Interest income recognized	10	36	71	74
Residential Portfolio Segment [Member]
Recorded investment, with no related allowance	588		588		544
Unpaid principal balance, with no related allowance	607		607		563
Recorded investment, with related allowance	120		120		430
Unpaid principal balance, with related allowance	120		120		430
Related allowance	31		31		62
Recorded investment	708		708		974
Unpaid principal balance	727		727		993
Average recorded investment, with no related allowance	606	551	585	499
Interest income recognized, with no related allowance	6	6	23	17
Average recorded investment, with related allowance	121	579	273	684
Interest income recognized, with related allowance	0	1	0	2
Average recorded investment	727	1,130	858	1,183
Interest income recognized	6	7	23	19
Commercial Real Estate Portfolio Segment [Member]
Related allowance	5		5		451
Commercial Real Estate Portfolio Segment [Member] \| Real Estate Loan [Member]
Recorded investment, with no related allowance	968		968		0
Unpaid principal balance, with no related allowance	1,618		1,618		0
Recorded investment, with related allowance	170		170		184
Unpaid principal balance, with related allowance	170		170		184
Related allowance	5		5		16
Recorded investment	1,138		1,138		184
Unpaid principal balance	1,788		1,788		184
Average recorded investment, with no related allowance	985		493
Interest income recognized, with no related allowance	0		33
Average recorded investment, with related allowance	173	191	177	195
Interest income recognized, with related allowance	0	0	0	0
Average recorded investment	1,158		670
Interest income recognized	0	0	33	0
Commercial Real Estate Portfolio Segment [Member] \| Commercial Real Estate Other [Member]
Recorded investment, with no related allowance	399		399		0
Unpaid principal balance, with no related allowance	479		479		0
Recorded investment, with related allowance	0		0		982
Unpaid principal balance, with related allowance	0		0		982
Related allowance	0		0		435
Recorded investment	399		399		982
Unpaid principal balance	479		479		982
Average recorded investment, with no related allowance	401	0	340	13
Interest income recognized, with no related allowance	0	0	2	0
Average recorded investment, with related allowance	0	1,061	487	1,065
Interest income recognized, with related allowance	0	20	0	22
Average recorded investment	401	1,061	827	1,078
Interest income recognized	0	20	2	22
Consumer Portfolio Segment [Member]
Recorded investment, with no related allowance	596		596		781
Unpaid principal balance, with no related allowance	596		596		781
Recorded investment, with related allowance	111		111		195
Unpaid principal balance, with related allowance	111		111		195
Related allowance	63		63		119
Recorded investment	707		707		976
Unpaid principal balance	707		707		976
Average recorded investment, with no related allowance	586	612	640	530
Interest income recognized, with no related allowance	3	3	9	17
Average recorded investment, with related allowance	142	192	169	241
Interest income recognized, with related allowance	0	3	2	8
Average recorded investment	728	804	809	771
Interest income recognized	3	6	11	25
Commercial Portfolio Segment [Member]
Recorded investment, with no related allowance	45		45		735
Unpaid principal balance, with no related allowance	597		597		1,287
Recorded investment, with related allowance	45		45		735
Unpaid principal balance, with related allowance	597		597		1,287
Related allowance	17		17		$ 93
Average recorded investment, with no related allowance	4		2
Interest income recognized, with no related allowance	0		0
Average recorded investment, with related allowance	50	248	242	286
Interest income recognized, with related allowance	1	3	2	8
Average recorded investment	54	248	244	286
Interest income recognized	$ 1	$ 3	$ 2	$ 8

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
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