Note 7 - Securities Available for Sale - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Due less than one year, amortized cost	$ 1,921
Due less than one year, fair value	1,878
Due after one year through five years, amortized cost	76,660
Due after one year through five years, fair value	74,842
Due after five years through ten years, amortized cost	3,036
Due after five years through ten years, fair value	2,953
Due after ten years, amortized cost	782
Due after ten years, fair value	673
No stated maturity, amortized cost	179
No stated maturity, fair value	179
Total, amortized cost	82,578	$ 78,801
Total, fair value	$ 80,525	$ 77,472