Note 7 - Securities - Available-for-sale Securities With Unrealized Loss Positions (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	$ 237,063	$ 142,924
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(4,465)	(1,022)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	17,351	63,752
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	(610)	(1,716)
Available-for-sale securities with unrealized loss positions, fair value	254,414	206,676
Available-for-sale securities, with unrealized loss positions, unrealized losses	(5,075)	(2,738)
US Government Agencies Debt Securities [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	7,899	0
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(135)	0
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	0	7,850
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	0	(192)
Available-for-sale securities with unrealized loss positions, fair value	7,899	7,850
Available-for-sale securities, with unrealized loss positions, unrealized losses	(135)	(192)
Obligations of States and Political Subdivisions Tax Exempt [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	54,479	5,200
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(1,676)	(19)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	1,278	216
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	(19)	(3)
Available-for-sale securities with unrealized loss positions, fair value	55,757	5,416
Available-for-sale securities, with unrealized loss positions, unrealized losses	(1,695)	(22)
Obligations of States and Political Subdivisions Taxable [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	9,594	10,605
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(79)	(60)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	0	2,910
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	0	(41)
Available-for-sale securities with unrealized loss positions, fair value	9,594	13,515
Available-for-sale securities, with unrealized loss positions, unrealized losses	(79)	(101)
Residential Pass-Through Securities [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	48,674	38,764
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(824)	(295)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	0	3,503
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	0	(75)
Available-for-sale securities with unrealized loss positions, fair value	48,674	42,267
Available-for-sale securities, with unrealized loss positions, unrealized losses	(824)	(370)
Residential Collateralized Mortgage Obligations [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	85,198	88,355
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(1,124)	(648)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	16,073	49,273
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	(591)	(1,405)
Available-for-sale securities with unrealized loss positions, fair value	101,271	137,628
Available-for-sale securities, with unrealized loss positions, unrealized losses	(1,715)	$ (2,053)
Commercial Mortgage Backed Securities [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	30,219
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(598)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	0
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	0
Available-for-sale securities with unrealized loss positions, fair value	30,219
Available-for-sale securities, with unrealized loss positions, unrealized losses	(598)
Debt Securities [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	236,063
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(4,436)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	17,351
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	(610)
Available-for-sale securities with unrealized loss positions, fair value	253,414
Available-for-sale securities, with unrealized loss positions, unrealized losses	(5,046)
Equity Securities [Member]
Available-for-sale securities with unrealized loss positions, less than 12 months, fair value	1,000
Available-for-sale securities with unrealized loss positions, less than 12 months, unrealized losses	(29)
Available-for-sale securities with unrealized loss positions, 12 months or more, fair value	0
Available-for-sale securities with unrealized loss positions, 12 months or more, unrealized losses	0
Available-for-sale securities with unrealized loss positions, fair value	1,000
Available-for-sale securities, with unrealized loss positions, unrealized losses	$ (29)