Note 4 - Loans Receivable and Related Allowance for Loan Losses - Nonaccrual Loans by Aging Category (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Nonaccrual	$ 3,433	$ 2,587
Residential Portfolio Segment [Member]
Nonaccrual	1,195	955
Home Equity Loans and Lines of Credit [Member]
Nonaccrual	317	428
Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	1,669	907
Commercial Portfolio Segment [Member]
Nonaccrual	206	215
Consumer Portfolio Segment [Member]
Nonaccrual	46	82
Not Past Due [Member]
Nonaccrual	1,292	277
Not Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual	227	245
Not Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual	3	4
Not Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	968	28
Not Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual	94
Not Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual
Financial Asset, 30 to 59 Days Past Due [Member]
Nonaccrual	188	309
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual	70
Financial Asset, 30 to 59 Days Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	118	309
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual
Financial Asset, 60 to 89 Days Past Due [Member]
Nonaccrual		278
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual		72
Financial Asset, 60 to 89 Days Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual		31
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual		175
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Nonaccrual	1,953	1,723
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual	898	638
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual	314	424
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	583	539
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual	112	40
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual	$ 46	$ 82