Note 3 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2014

Investments, Debt and Equity Securities [Abstract]

Investment [Table Text Block]

	Years Ended December 31
	2014									2013
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Held-to-Maturity
U.S. Government agencies	$	418,914	$	929	$	(4,055	)	$	415,788	$	395,198	$	50	$	(10,535	)	$	384,713
Mortgage-backed securities		29,743		56		(411	)		29,388		34,425		17		(442	)		34,000
State and political subdivisions		328,310		7,000		(573	)		334,737		315,445		2,165		(5,498	)		312,112
Other securities		620		-		-			620		620		-		-			620
Total	$	777,587	$	7,985	$	(5,039	)	$	780,533	$	745,688	$	2,232	$	(16,475	)	$	731,445
Available-for-Sale
U.S. Treasury	$	4,000	$	1	$	(9	)	$	3,992	$	4,001	$	-	$	(16	)	$	3,985
U.S. Government agencies		275,381		15		(2,580	)		272,816		183,781		8		(5,572	)		178,217
Mortgage-backed securities		1,579		-		(7	)		1,572		1,735		156		-			1,891
State and political subdivisions		6,536		7		(3	)		6,540		7,860		4		(3	)		7,861
Other securities		19,985		386		(8	)		20,363		19,840		484		(1	)		20,323
Total	$	307,481	$	409	$	(2,607	)	$	305,283	$	217,217	$	652	$	(5,592	)	$	212,277

Schedule of Unrealized Loss on Investments [Table Text Block]

	Less Than 12 Months				12 Months or More				Total
(In thousands)	Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses
December 31, 2014
Held-to-Maturity
U.S. Government agencies	$	265,591	$	2,500	$	84,398	$	1,555	$	349,989	$	4,055
Mortgage-backed securities		10,077		67		14,250		344		24,327		411
State and political subdivisions		57,607		444		8,976		129		66,583		573
Total	$	333,275	$	3,011	$	107,624	$	2,028	$	440,899	$	5,039
Available-for-Sale
U.S. Treasury	$	3,992	$	9	$	-	$	-	$	3,992	$	9
U.S. Government agencies		171,114		1,472		61,195		1,108		232,309		2,580
Mortgage-backed securities		1,542		7		-		-		1,542		7
State and political subdivisions		1,005		3		-		-		1,005		3
Other securities		764		8		-		-		764		8
Total	$	178,417	$	1,499	$	61,195	$	1,108	$	239,612	$	2,607
December 31, 2013
Held-to-Maturity
U.S. Government agencies	$	258,474	$	6,405	$	114,339	$	4,130	$	372,814	$	10,535
Mortgage-backed securities		32,053		442		-		-		32,053		442
State and political subdivisions		130,457		5,311		4,466		187		134,923		5,498
Total	$	420,984	$	12,158	$	118,805	$	4,317	$	539,790	$	16,475
Available-for-Sale
U.S. Government agencies	$	3,985	$	16	$	-	$	-	$	3,985	$	16
Mortgage-backed securities		111,662		2,682		56,396		2,890		168,058		5,572
State and political subdivisions		2,921		3		-		-		2,921		3
Other securities		573		1		-		-		573		1
Total	$	119,141	$	2,702	$	56,396	$	2,890	$	175,537	$	5,592

Investment Income [Table Text Block]

(In thousands)	2014		2013		2012
Taxable
Held-to-maturity	$	5,839	$	3,314	$	3,107
Available-for-sale		2,785		2,239		2,214
Non-taxable
Held-to-maturity		10,625		7,682		7,395
Available-for-sale		108		65		5
Total	$	19,357	$	13,300	$	12,721

Investments Classified by Contractual Maturity Date [Table Text Block]

	Held-to-Maturity				Available-for-Sale
(In thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
One year or less	$	23,068	$	23,126	$	3,268	$	3,268
After one through five years		415,154		412,294		240,190		238,298
After five through ten years		133,646		134,639		43,260		42,575
After ten years		205,719		210,474		1,549		1,542
Other securities		-		-		19,214		19,600
Total	$	777,587	$	780,533	$	307,481	$	305,283