Note 6 - Investment Securities (Tables)

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Schedule of Available-for-sale Securities Reconciliation [Table Text Block]

	March 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	224,750	$	61	$	7	$	224,804
U.S. government sponsored entities		100,000		10		-		100,010
Mortgage-backed securities		1,063,944		6,553		4		1,070,493
Collateralized mortgage obligations		60		-		26		34
Corporate debt securities		74,957		413		2,267		73,103
Mutual funds		6,000		-		85		5,915
Preferred stock of government sponsored entities		2,811		478		486		2,803
Other equity securities		3,902		4,060		-		7,962
Total	$	1,476,424	$	11,575	$	2,875	$	1,485,124

	December 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	284,678	$	5	$	395	$	284,288
U.S. government sponsored entities		150,000		-		1,840		148,160
Mortgage-backed securities		1,073,108		560		11,399		1,062,269
Collateralized mortgage obligations		63		-		27		36
Corporate debt securities		74,955		425		1,525		73,855
Mutual funds		6,000		-		167		5,833
Preferred stock of government sponsored entities		2,811		633		228		3,216
Other equity securities		4,108		4,929		342		8,695
Total	$	1,595,723	$	6,552	$	15,923	$	1,586,352

Investments Classified by Contractual Maturity Date [Table Text Block]

	Securities Available-For-Sale
	Amortized cost		Fair value
	(In thousands)
Due in one year or less	$	154,963	$	154,978
Due after one year through five years		104,879		105,470
Due after five years through ten years		145,501		143,358
Due after ten years (1)		1,071,081		1,081,318
Total	$	1,476,424	$	1,485,124

Schedule of Unrealized Loss on Investments [Table Text Block]

	March 31, 2016
	Temporarily impaired securities
	Less than 12 months				12 months or longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
	(Dollars in thousands)
Securities Available-for-Sale
U.S. treasury securities	$	29,965	$	7	$	-	$	-	$	29,965	$	7
Mortgage-backed securities		389		3		46		1		435		4
Collateralized mortgage obligations		-		-		34		26		34		26
Corporate debt securities		9,950		50		42,783		2,217		52,733		2,267
Mutual funds		-		-		5,915		85		5,915		85
Preferred stock of government sponsored entities		2,230		486		-		-		2,230		486
Total	$	42,534	$	546	$	48,778	$	2,329	$	91,312	$	2,875

	December 31, 2015
	Temporarily impaired securities
	Less than 12 months				12 months or longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
	(Dollars in thousands)
Securities Available-for-Sale
U.S. treasury securities	$	224,289	$	395	$	-	$	-	$	224,289	$	395
U.S. government sponsored entities		148,160		1,840		-		-		148,160		1,840
Mortgage-backed securities		1,025,342		11,398		6		1		1,025,348		11,399
Collateralized mortgage obligations		-		-		36		27		36		27
Corporate debt securities		9,950		50		43,525		1,475		53,475		1,525
Mutual funds		-		-		5,833		167		5,833		167
Preferred stock of government sponsored entities		2,488		228		-		-		2,488		228
Other equity securities		158		342		-		-		158		342
Total	$	1,410,387	$	14,253	$	49,400	$	1,670	$	1,459,787	$	15,923