Note 3 - Loans Receivable and Related Allowance for Loan Losses - Classes of Loan Portfolio by Aging Categories (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accruing loans not past due	$ 701,016	$ 574,298
Nonaccrual	2,237	3,003
Loans	715,172	583,361
Financing Receivables, 30 to 59 Days Past Due [Member]
Accruing loans past due	9,516	3,907
Nonaccrual	265
Financing Receivables, 60 to 89 Days Past Due [Member]
Accruing loans past due	1,612	1,463
Nonaccrual	113	75
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accruing loans past due	791	690
Nonaccrual	1,407	1,644
Residential Portfolio Segment [Member]
Accruing loans not past due	289,732	218,515
Nonaccrual	855	856
Loans	295,405	221,823
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Accruing loans past due	3,586	1,936
Nonaccrual
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Accruing loans past due	747	357
Nonaccrual	74	75
Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accruing loans past due	485	159
Nonaccrual	446	415
Home Equity Loans and Lines of Credit [Member]
Accruing loans not past due	101,920	98,112
Nonaccrual	487	526
Loans	103,752	99,940
Home Equity Loans and Lines of Credit [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Accruing loans past due	707	598
Nonaccrual
Home Equity Loans and Lines of Credit [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Accruing loans past due	351	370
Nonaccrual
Home Equity Loans and Lines of Credit [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accruing loans past due	287	334
Nonaccrual	481	518
Commercial Real Estate Portfolio Segment [Member]
Accruing loans not past due	232,865	190,451
Nonaccrual	606	964
Loans	238,734	193,068
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Accruing loans past due	5,013	1,026
Nonaccrual	265
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Accruing loans past due	231	430
Nonaccrual
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accruing loans past due	19	197
Nonaccrual	230	623
Commercial Portfolio Segment [Member]
Accruing loans not past due	65,538	58,058
Nonaccrual	174	584
Loans	66,009	58,941
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Accruing loans past due	50	74
Nonaccrual
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Accruing loans past due	247	225
Nonaccrual	39
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accruing loans past due
Nonaccrual	135	15
Consumer Portfolio Segment [Member]
Accruing loans not past due	10,961	9,162
Nonaccrual	115	73
Loans	11,272	9,589
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Accruing loans past due	160	273
Nonaccrual
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Accruing loans past due	36	81
Nonaccrual
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accruing loans past due
Nonaccrual	$ 115	$ 73