Note 3 - Investment Securities (Details) - Securities in a Continuous Unrealized Loss Position - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Note 3 - Investment Securities (Details) - Securities in a Continuous Unrealized Loss Position [Line Items]
Less than 12 months, fair value	$ 110,442	$ 34,806
Less than 12 months, unrealized loss	(556)	(229)
12 months or more, fair value	46,393	138,981
12 months or more, unrealized loss	(702)	(1,988)
Total, fair value	156,835	173,787
Total, unrealized loss	(1,258)	(2,217)
US States and Political Subdivisions Debt Securities [Member]
Note 3 - Investment Securities (Details) - Securities in a Continuous Unrealized Loss Position [Line Items]
Less than 12 months, fair value	31,378	19,386
Less than 12 months, unrealized loss	(308)	(145)
12 months or more, fair value	5,269	21,198
12 months or more, unrealized loss	(91)	(307)
Total, fair value	36,647	40,584
Total, unrealized loss	(399)	(452)
Pass-Through Mortgage Securities [Member]
Note 3 - Investment Securities (Details) - Securities in a Continuous Unrealized Loss Position [Line Items]
Less than 12 months, fair value	60,790
Less than 12 months, unrealized loss	(232)
12 months or more, fair value	28,997	100,556
12 months or more, unrealized loss	(340)	(1,206)
Total, fair value	89,787	100,556
Total, unrealized loss	(572)	(1,206)
Collateralized Mortgage Obligations [Member]
Note 3 - Investment Securities (Details) - Securities in a Continuous Unrealized Loss Position [Line Items]
Less than 12 months, fair value	18,274	15,420
Less than 12 months, unrealized loss	(16)	(84)
12 months or more, fair value	12,127	17,227
12 months or more, unrealized loss	(271)	(475)
Total, fair value	30,401	32,647
Total, unrealized loss	$ (287)	$ (559)