Note 7 - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Due in one year or less	$ 6,140
Due after one year through five years	240,710
Due after five years through ten years	101,608
Due after ten years	12,311
Equity securities	8,065
Investment securities available-for-sale	368,834	$ 361,915
Due in one year or less	6,085
Due after one year through five years	237,900
Due after five years through ten years	100,465
Due after ten years	12,858
Equity securities	8,059
Investment securities available-for-sale, amortized cost	365,367	362,742
Due in one year or less	147
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	0
Held-to-maturity, fair value	147	151
Due in one year or less	147
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	0
Total investment securities held-to-maturity	$ 147	$ 147