Note 3 - Investment Securities - Maturities of Investment Securities Available-for-sale and Held-to-maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Due in one year or less, amortized cost	$ 2,115
Due in one year or less, fair value	2,126
Due after one year through five years, amortized cost	23,469
Due after one year through five years, fair value	23,443
Due after five years through ten years, amortized cost	68,376
Due after five years through ten years, fair value	67,362
Due after ten years, amortized cost	22,921
Due after ten years, fair value	22,958
Total, amortized cost	116,881	$ 107,994
Total, fair value	$ 115,889	$ 106,208