Note 4 - Loans Receivable and Related Allowance for Loan Losses - Classes of Loan Portfolio by Aging Categories (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Loans	$ 804,139	$ 809,918
Nonaccrual	2,852	3,523
Financial Asset, Not Past Due [Member]
Loans	797,408	802,158
Financial Asset, 30 to 59 Days Past Due [Member]
Loans	2,332	2,962
Nonaccrual	20	70
Financial Asset, 60 to 89 Days Past Due [Member]
Loans	938	696
Nonaccrual	129	24
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	609	579
Nonaccrual	1,501	2,021
Residential Portfolio Segment [Member]
Loans	288,378	308,031
Nonaccrual	1,251	1,619
Residential Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	284,959	304,161
Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	1,365	1,836
Nonaccrual	0	70
Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	444	239
Nonaccrual	69	0
Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	359	176
Nonaccrual	974	1,329
Home Equity Loans and Lines of Credit [Member]
Loans	80,552	87,088
Nonaccrual	132	75
Home Equity Loans and Lines of Credit [Member] | Financial Asset, Not Past Due [Member]
Loans	79,448	86,093
Home Equity Loans and Lines of Credit [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	534	446
Nonaccrual	0	0
Home Equity Loans and Lines of Credit [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	423	328
Nonaccrual	0	0
Home Equity Loans and Lines of Credit [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	15	146
Nonaccrual	128	71
Commercial Real Estate Portfolio Segment [Member]
Loans	303,501	285,625
Nonaccrual	1,312	1,613
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	301,768	283,373
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	421	580
Nonaccrual	20	0
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	0	41
Nonaccrual	60	24
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	0	18
Nonaccrual	383	573
Commercial Portfolio Segment [Member]
Loans	85,622	89,139
Nonaccrual	141	168
Commercial Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	85,240	88,614
Commercial Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	6	72
Nonaccrual	0	0
Commercial Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	0	46
Nonaccrual	0	0
Commercial Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	235	239
Nonaccrual	0	0
Consumer Portfolio Segment [Member]
Loans	46,086	40,035
Nonaccrual	16	48
Consumer Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	45,993	39,917
Consumer Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	6	28
Nonaccrual	0	0
Consumer Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	71	42
Nonaccrual	0	0
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	0	0
Nonaccrual	$ 16	$ 48