Note 4 - Loans Receivable and Related Allowance for Loan Losses - Classes of Loan Portfolio by Aging Categories (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accruing loans not past due	$ 799,888	$ 690,985
Nonaccrual	3,309	2,587
Loans	811,891	701,904
Financial Asset, 30 to 59 Days Past Due [Member]
Accruing loans past due	6,065	5,481
Nonaccrual	141	309
Financial Asset, 60 to 89 Days Past Due [Member]
Accruing loans past due	856	2,222
Nonaccrual	171	278
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accruing loans past due	1,773	629
Nonaccrual	1,726	1,723
Residential Portfolio Segment [Member]
Accruing loans not past due	303,425	288,399
Nonaccrual	906	955
Loans	306,986	293,170
Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accruing loans past due	1,440	2,405
Nonaccrual	70
Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accruing loans past due	581	1,039
Nonaccrual		72
Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accruing loans past due	634	372
Nonaccrual	603	638
Home Equity Loans and Lines of Credit [Member]
Accruing loans not past due	92,781	95,908
Nonaccrual	339	428
Loans	93,652	97,541
Home Equity Loans and Lines of Credit [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accruing loans past due	425	626
Nonaccrual
Home Equity Loans and Lines of Credit [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accruing loans past due		553
Nonaccrual
Home Equity Loans and Lines of Credit [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accruing loans past due	107	26
Nonaccrual	336	424
Commercial Real Estate Portfolio Segment [Member]
Accruing loans not past due	258,366	226,133
Nonaccrual	1,709	907
Loans	264,909	229,951
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accruing loans past due	3,908	2,141
Nonaccrual	71	309
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accruing loans past due	134	543
Nonaccrual	171	31
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accruing loans past due	792	227
Nonaccrual	527	539
Commercial Portfolio Segment [Member]
Accruing loans not past due	116,728	66,087
Nonaccrual	238	215
Loans	117,399	66,603
Commercial Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accruing loans past due	67	225
Nonaccrual
Commercial Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accruing loans past due	126	72
Nonaccrual		175
Commercial Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accruing loans past due	240	4
Nonaccrual	143	40
Consumer Portfolio Segment [Member]
Accruing loans not past due	28,588	14,458
Nonaccrual	117	82
Loans	28,945	14,639
Consumer Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accruing loans past due	225	84
Nonaccrual
Consumer Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accruing loans past due	15	15
Nonaccrual
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accruing loans past due
Nonaccrual	$ 117	$ 82