Note 3 - Investment Securities (Details) - Maturities of Investment Securities - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Maturities of Investment Securities [Abstract]
One year or less	$ 52,552
One year or less	52,603
One year or less	21,853
One year or less	21,833
After one through five years	379,913
After one through five years	379,511
After one through five years	183,376
After one through five years	182,746
After five through ten years	177,863
After five through ten years	179,113
After five through ten years	116,360
After five through ten years	116,088
After ten years	251,268
After ten years	252,122
After ten years	396,901
After ten years	395,933
Other securities (no maturity)	31,515
Other securities (no maturity)	31,101
Total	861,596	$ 777,587
Total	863,349	780,533
Total	750,005	307,481
Total	$ 747,701	$ 305,283