Note 9 - Allowance for Loan Losses and Credit Quality Information - Aging of Past Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loans past due	$ 1,811	$ 2,396
Current loans	679,006	602,039
Loans receivable	680,817	604,435
Loans 90 days or more past due and still accruing	0	0
Residential Portfolio Segment [Member]
Loans past due	917	922
Current loans	129,926	119,142
Loans receivable	130,843	120,064
Loans 90 days or more past due and still accruing	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	383,907	350,195
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans past due	0	0
Current loans	213,696	192,502
Loans receivable	213,696	192,502
Loans 90 days or more past due and still accruing	0	0
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans past due	185	0
Current loans	170,026	157,693
Loans receivable	170,211	157,693
Loans 90 days or more past due and still accruing	0	0
Consumer Portfolio Segment [Member]
Loans past due	709	764
Current loans	58,562	69,185
Loans receivable	59,271	69,949
Loans 90 days or more past due and still accruing	0	0
Commercial Portfolio Segment [Member]
Loans past due	0	710
Current loans	106,796	63,517
Loans receivable	106,796	64,227
Loans 90 days or more past due and still accruing	0	0
Financial Asset, 30 to 59 Days Past Due [Member]
Loans past due	910	1,460
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans past due	550	786
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans past due	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans past due	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans past due	360	527
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans past due	0	147
Financial Asset, 60 to 89 Days Past Due [Member]
Loans past due	272	121
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans past due	223	77
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans past due	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans past due	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans past due	49	31
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans past due	0	13
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans past due	629	815
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member]
Loans past due	144	59
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans past due	0	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 past due	185	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Loans past due	300	206
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans past due	$ 0	$ 550