Note 4 - Loans and Allowance for Loan Losses - Risk Category of Commercial Loans by Class of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans receivable	$ 768,065	$ 769,319
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	211,687	213,446
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	69,649	73,573
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	104,683	101,571
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	37,355	38,302
Commercial and Industrial Portfolio Segment [Member]
Loans receivable	113,564	107,089
Commercial Portfolio Segment [Member]
Loans receivable	325,251	320,535
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	60,371	64,993
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	98,628	93,197
Pass [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	37,049	37,735
Pass [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans receivable	98,322	91,097
Pass [Member] | Commercial Portfolio Segment [Member]
Loans receivable	294,370	287,022
Criticized [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	908	934
Criticized [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	1,952	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	5,922	6,058
Criticized [Member] | Commercial Portfolio Segment [Member]
Loans receivable	8,916	10,924
Classified [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans receivable	8,370	7,646
Classified [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans receivable	4,103	4,598
Classified [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans receivable	172	411
Classified [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans receivable	9,320	9,934
Classified [Member] | Commercial Portfolio Segment [Member]
Loans receivable	$ 21,965	$ 22,589