Note 9 - Allowance for Loan Losses and Credit Quality Information - Aging of Past Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Loans receivable	$ 631,698	$ 653,791
Loans 90 days or more past due and still accruing	0	0
Residential Portfolio Segment [Member]
Loans receivable	157,502	135,023
Loans 90 days or more past due and still accruing	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	375,700	380,704
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans receivable	196,167	202,400
Loans 90 days or more past due and still accruing	0	0
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans receivable	179,533	178,304
Loans 90 days or more past due and still accruing	0	0
Consumer Portfolio Segment [Member]
Loans receivable	42,753	55,391
Loans 90 days or more past due and still accruing	0	0
Commercial Portfolio Segment [Member]
Loans receivable	55,743	82,673
Loans 90 days or more past due and still accruing	0	0
Financial Asset, 30 to 59 Days Past Due [Member]
Loans receivable	1,291	1,084
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans receivable	1,072	626
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans receivable	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans receivable	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans receivable	219	458
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable	0	0
Financial Asset, 60 to 89 Days Past Due [Member]
Loans receivable	86	104
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans receivable	47	38
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans receivable	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans receivable	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans receivable	39	66
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans receivable	724	577
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans receivable	161	298
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans receivable	325	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans receivable	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans receivable	238	279
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable	0	0
Financial Asset, Past Due [Member]
Loans receivable	2,101	1,765
Financial Asset, Past Due [Member] | Residential Portfolio Segment [Member]
Loans receivable	1,280	962
Financial Asset, Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans receivable	325	0
Financial Asset, Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans receivable	0	0
Financial Asset, Past Due [Member] | Consumer Portfolio Segment [Member]
Loans receivable	496	803
Financial Asset, Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable	0	0
Financial Asset, Not Past Due [Member]
Loans receivable	629,597	652,026
Financial Asset, Not Past Due [Member] | Residential Portfolio Segment [Member]
Loans receivable	156,222	134,061
Financial Asset, Not Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans receivable	195,842	202,400
Financial Asset, Not Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans receivable	179,533	178,304
Financial Asset, Not Past Due [Member] | Consumer Portfolio Segment [Member]
Loans receivable	42,257	54,588
Financial Asset, Not Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable	$ 55,743	$ 82,673