Note 9 - Allowance for Loan Losses and Credit Quality Information - Classified and Unclassified Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans receivable	$ 600,538	$ 594,798
Classified [Member]
Loans receivable	39,965	36,669
Classified [Member] | Special Mention [Member]
Loans receivable	23,834	20,015
Classified [Member] | Substandard [Member]
Loans receivable	15,880	16,361
Classified [Member] | Doubtful [Member]
Loans receivable	96	163
Classified [Member] | Unlikely to be Collected Financing Receivable [Member]
Loans receivable	155	130
Unclassified [Member]
Loans receivable	560,573	558,129
Residential Portfolio Segment [Member]
Loans receivable	107,055	107,005
Residential Portfolio Segment [Member] | Classified [Member]
Loans receivable	1,927	2,275
Residential Portfolio Segment [Member] | Classified [Member] | Special Mention [Member]
Loans receivable	108	77
Residential Portfolio Segment [Member] | Classified [Member] | Substandard [Member]
Loans receivable	1,775	2,154
Residential Portfolio Segment [Member] | Classified [Member] | Doubtful [Member]
Loans receivable	44	44
Residential Portfolio Segment [Member] | Classified [Member] | Unlikely to be Collected Financing Receivable [Member]
Loans receivable	0	0
Residential Portfolio Segment [Member] | Unclassified [Member]
Loans receivable	105,128	104,730
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	343,831	334,117
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Loans receivable	188,450	175,177
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Loans receivable	155,381	158,940
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Real Estate Loan [Member]
Loans receivable	10,657	8,835
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Commercial Real Estate Other [Member]
Loans receivable	14,709	13,392
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Special Mention [Member] | Real Estate Loan [Member]
Loans receivable	7,272	5,022
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Special Mention [Member] | Commercial Real Estate Other [Member]
Loans receivable	8,839	9,135
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Substandard [Member] | Real Estate Loan [Member]
Loans receivable	3,385	3,813
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Substandard [Member] | Commercial Real Estate Other [Member]
Loans receivable	5,870	4,257
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Doubtful [Member] | Real Estate Loan [Member]
Loans receivable	0	0
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Doubtful [Member] | Commercial Real Estate Other [Member]
Loans receivable	0	0
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Unlikely to be Collected Financing Receivable [Member] | Real Estate Loan [Member]
Loans receivable	0	0
Commercial Real Estate Portfolio Segment [Member] | Classified [Member] | Unlikely to be Collected Financing Receivable [Member] | Commercial Real Estate Other [Member]
Loans receivable	0	0
Commercial Real Estate Portfolio Segment [Member] | Unclassified [Member] | Real Estate Loan [Member]
Loans receivable	177,793	166,342
Commercial Real Estate Portfolio Segment [Member] | Unclassified [Member] | Commercial Real Estate Other [Member]
Loans receivable	140,672	145,548
Consumer Portfolio Segment [Member]
Loans receivable	72,770	73,767
Consumer Portfolio Segment [Member] | Classified [Member]
Loans receivable	859	880
Consumer Portfolio Segment [Member] | Classified [Member] | Special Mention [Member]
Loans receivable	0	0
Consumer Portfolio Segment [Member] | Classified [Member] | Substandard [Member]
Loans receivable	652	631
Consumer Portfolio Segment [Member] | Classified [Member] | Doubtful [Member]
Loans receivable	52	119
Consumer Portfolio Segment [Member] | Classified [Member] | Unlikely to be Collected Financing Receivable [Member]
Loans receivable	155	130
Consumer Portfolio Segment [Member] | Unclassified [Member]
Loans receivable	71,911	72,887
Commercial Portfolio Segment [Member]
Loans receivable	76,882	79,909
Commercial Portfolio Segment [Member] | Classified [Member]
Loans receivable	11,813	11,287
Commercial Portfolio Segment [Member] | Classified [Member] | Special Mention [Member]
Loans receivable	7,615	5,781
Commercial Portfolio Segment [Member] | Classified [Member] | Substandard [Member]
Loans receivable	4,198	5,506
Commercial Portfolio Segment [Member] | Classified [Member] | Doubtful [Member]
Loans receivable	0	0
Commercial Portfolio Segment [Member] | Classified [Member] | Unlikely to be Collected Financing Receivable [Member]
Loans receivable	0	0
Commercial Portfolio Segment [Member] | Unclassified [Member]
Loans receivable	$ 65,069	$ 68,622