Note 5 - Loans Receivable and Related Allowance for Loan Losses - Nonaccrual Loans by Aging Category (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Nonaccrual	$ 4,953	$ 3,003
Residential Portfolio Segment [Member]
Nonaccrual	1,083	856
Home Equity Loans and Lines of Credit [Member]
Nonaccrual	521	526
Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	3,240	964
Commercial Portfolio Segment [Member]
Nonaccrual	39	584
Consumer Portfolio Segment [Member]
Nonaccrual	70	73
Not Past Due [Member]
Nonaccrual	3,057	1,284
Not Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual	346	366
Not Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual	7	8
Not Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	2,665	341
Not Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual	39	569
Not Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual
Financing Receivables, 30 to 59 Days Past Due [Member]
Nonaccrual
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual
Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual
Financing Receivables, 60 to 89 Days Past Due [Member]
Nonaccrual	342	75
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual	74	75
Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	268
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Nonaccrual	1,554	1,644
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member]
Nonaccrual	663	415
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity Loans and Lines of Credit [Member]
Nonaccrual	514	518
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Nonaccrual	307	623
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Nonaccrual		15
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Nonaccrual	$ 70	$ 73