Note 4 - Loans and Allowance for Loan Losses - Risk Category of Commercial Loans by Class of Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans receivable	$ 781,980	$ 769,319
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	222,535	213,446
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	66,171	73,573
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	116,476	101,571
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	39,888	38,302
Commercial and Industrial Portfolio Segment [Member]
Loans receivable	114,838	107,089
Commercial Portfolio Segment [Member]
Loans receivable	337,373	320,535
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	56,810	64,993
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	112,057	93,197
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	39,583	37,735
Pass [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans receivable	96,185	91,097
Pass [Member] | Commercial Portfolio Segment [Member]
Loans receivable	304,635	287,022
Criticized [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	1,057	934
Criticized [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	855	3,776
Criticized [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	134	156
Criticized [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans receivable	8,508	6,058
Criticized [Member] | Commercial Portfolio Segment [Member]
Loans receivable	10,554	10,924
Classified [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	8,304	7,646
Classified [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	3,564	4,598
Classified [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	171	411
Classified [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans receivable	10,145	9,934
Classified [Member] | Commercial Portfolio Segment [Member]
Loans receivable	$ 22,184	$ 22,589