Note 4 - Loans Receivable and Related Allowance for Loan Losses - Loan Portfolio by Internal Risk Rating (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Loans	$ 741,950	$ 701,904
Residential Portfolio Segment [Member]
Loans	294,361	293,170
Home Equity Loans and Lines of Credit [Member]
Loans	95,459	97,541
Commercial Real Estate Portfolio Segment [Member]
Loans	263,948	229,951
Commercial Portfolio Segment [Member]
Loans	69,077	66,603
Consumer Portfolio Segment [Member]
Loans	19,105	14,639
Not Rated [Member]
Loans	407,402	403,487
Not Rated [Member] | Residential Portfolio Segment [Member]
Loans	293,491	291,843
Not Rated [Member] | Home Equity Loans and Lines of Credit [Member]
Loans	94,928	97,087
Not Rated [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans
Not Rated [Member] | Commercial Portfolio Segment [Member]
Loans
Not Rated [Member] | Consumer Portfolio Segment [Member]
Loans	18,983	14,557
Pass [Member]
Loans	318,376	281,380
Pass [Member] | Residential Portfolio Segment [Member]
Loans
Pass [Member] | Home Equity Loans and Lines of Credit [Member]
Loans
Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	251,246	216,744
Pass [Member] | Commercial Portfolio Segment [Member]
Loans	67,130	64,636
Pass [Member] | Consumer Portfolio Segment [Member]
Loans
Special Mention [Member]
Loans	5,362	5,574
Special Mention [Member] | Residential Portfolio Segment [Member]
Loans
Special Mention [Member] | Home Equity Loans and Lines of Credit [Member]
Loans
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	5,159	5,370
Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans	203	204
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans
Substandard [Member]
Loans	10,810	11,463
Substandard [Member] | Residential Portfolio Segment [Member]
Loans	870	1,327
Substandard [Member] | Home Equity Loans and Lines of Credit [Member]
Loans	531	454
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	7,543	7,837
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans	1,744	1,763
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans	122	82
Doubtful [Member]
Loans
Doubtful [Member] | Residential Portfolio Segment [Member]
Loans
Doubtful [Member] | Home Equity Loans and Lines of Credit [Member]
Loans
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans
Doubtful [Member] | Commercial Portfolio Segment [Member]
Loans
Doubtful [Member] | Consumer Portfolio Segment [Member]
Loans