Note 4 -Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2016 USD ($) security	Dec. 31, 2015 USD ($) security
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	306	193
Securities in an unrealized loss position less than 12 months, fair value	$ 288,833	$ 176,786
Securities in an unrealized loss position less than 12 months, unrealized losses	(6,351)	(2,359)
Securities in an unrealized loss position 12 months or longer, fair value	18,266	36,124
Securities in an unrealized loss position 12 months or longer, unrealized losses	(1,528)	(2,022)
Securities in an unrealized loss position, fair value	307,099	212,910
Securities in an unrealized loss position, unrealized losses	$ (7,879)	$ (4,381)
US Government Agencies Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	55	32
Securities in an unrealized loss position less than 12 months, fair value	$ 72,626	$ 40,949
Securities in an unrealized loss position less than 12 months, unrealized losses	(2,118)	(418)
Securities in an unrealized loss position 12 months or longer, fair value		4,426
Securities in an unrealized loss position 12 months or longer, unrealized losses		(72)
Securities in an unrealized loss position, fair value	72,626	45,375
Securities in an unrealized loss position, unrealized losses	$ (2,118)	$ (490)
US States and Political Subdivisions Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	70	20
Securities in an unrealized loss position less than 12 months, fair value	$ 29,280	$ 6,646
Securities in an unrealized loss position less than 12 months, unrealized losses	(398)	(19)
Securities in an unrealized loss position 12 months or longer, fair value		1,555
Securities in an unrealized loss position 12 months or longer, unrealized losses		(12)
Securities in an unrealized loss position, fair value	29,280	8,201
Securities in an unrealized loss position, unrealized losses	$ (398)	$ (31)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	88	62
Securities in an unrealized loss position less than 12 months, fair value	$ 123,087	$ 90,796
Securities in an unrealized loss position less than 12 months, unrealized losses	(2,241)	(871)
Securities in an unrealized loss position 12 months or longer, fair value		1,403
Securities in an unrealized loss position 12 months or longer, unrealized losses		(49)
Securities in an unrealized loss position, fair value	123,087	92,199
Securities in an unrealized loss position, unrealized losses	$ (2,241)	$ (920)
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	68	49
Securities in an unrealized loss position less than 12 months, fair value	$ 56,853	$ 28,372
Securities in an unrealized loss position less than 12 months, unrealized losses	(1,269)	(261)
Securities in an unrealized loss position 12 months or longer, fair value	15,426	26,354
Securities in an unrealized loss position 12 months or longer, unrealized losses	(577)	(917)
Securities in an unrealized loss position, fair value	72,279	54,726
Securities in an unrealized loss position, unrealized losses	$ (1,846)	$ (1,178)
Collateralized Debt Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	5	5
Securities in an unrealized loss position less than 12 months, fair value	$ 0	$ 0
Securities in an unrealized loss position less than 12 months, unrealized losses	0	0
Securities in an unrealized loss position 12 months or longer, fair value	1,952	2,193
Securities in an unrealized loss position 12 months or longer, unrealized losses	(891)	(897)
Securities in an unrealized loss position, fair value	1,952	2,193
Securities in an unrealized loss position, unrealized losses	$ (891)	$ (897)
Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	4	6
Securities in an unrealized loss position less than 12 months, fair value	$ 4,002	$ 5,988
Securities in an unrealized loss position less than 12 months, unrealized losses	(57)	(95)
Securities in an unrealized loss position, fair value	4,002	5,988
Securities in an unrealized loss position, unrealized losses	$ (57)	$ (95)
Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
No. of securities | security	16	19
Securities in an unrealized loss position less than 12 months, fair value	$ 2,985	$ 4,035
Securities in an unrealized loss position less than 12 months, unrealized losses	(268)	(695)
Securities in an unrealized loss position 12 months or longer, fair value	888	193
Securities in an unrealized loss position 12 months or longer, unrealized losses	(60)	(75)
Securities in an unrealized loss position, fair value	3,873	4,228
Securities in an unrealized loss position, unrealized losses	$ (328)	$ (770)