Note 3 - Investment Securities (Tables)

9 Months Ended

Sep. 30, 2023

Notes Tables

Debt Securities, Available-for-sale and Held-to-maturity [Table Text Block]

	At September 30, 2023
			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
	(In thousands)
Debt securities available for sale:
Agency residential mortgage-backed securities ("MBS")	$	269,883	$	-	$	(30,155	)	$	239,728
Securities of U.S. Government sponsored entities		308,160		-		(28,796	)		279,364
Obligations of states and political subdivisions		73,614		4		(3,979	)		69,639
Corporate securities		2,134,535		625		(320,736	)		1,814,424
Collateralized loan obligations		1,525,669		702		(23,293	)		1,503,078
Total debt securities available for sale		4,311,861		1,331		(406,959	)		3,906,233
Debt securities held to maturity:
Agency residential MBS		84,347		9		(8,116	)		76,240
Obligations of states and political subdivisions		77,559		4		(1,957	)		75,606
Corporate securities		726,951		-		(60,402	)		666,549
Total debt securities held to maturity		888,857		13		(70,475	)		818,395
Total	$	5,200,718	$	1,344	$	(477,434	)	$	4,724,628

	At December 31, 2022
			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
	(In thousands)
Debt securities available for sale:
Agency residential MBS	$	311,089	$	4	$	(25,045	)	$	286,048
Securities of U.S. Government sponsored entities		306,336		3		(15,486	)		290,853
Obligations of states and political subdivisions		84,024		59		(2,079	)		82,004
Corporate securities		2,406,566		1,032		(307,643	)		2,099,955
Collateralized loan obligations		1,587,326		527		(14,970	)		1,572,883
Total debt securities available for sale		4,695,341		1,625		(365,223	)		4,331,743
Debt securities held to maturity:
Agency residential MBS		104,852		13		(7,503	)		97,362
Obligations of states and political subdivisions		89,208		73		(538	)		88,743
Corporate securities		721,854		-		(34,448	)		687,406
Total debt securities held to maturity		915,914		86		(42,489	)		873,511
Total	$	5,611,255	$	1,711	$	(407,712	)	$	5,205,254

Investments Classified by Contractual Maturity Date [Table Text Block]

	At September 30, 2023
	Debt Securities Available				Debt Securities Held
	for Sale				to Maturity
	Amortized		Fair		Amortized		Fair
	Cost		Value		Cost		Value
	(In thousands)
Maturity in years:
1 year or less	$	45,005	$	44,479	$	17,851	$	17,714
Over 1 to 5 years		773,732		715,554		273,548		259,494
Over 5 to 10 years		2,667,773		2,362,742		513,111		464,947
Over 10 years		555,468		543,730		-		-
Subtotal		4,041,978		3,666,505		804,510		742,155
MBS		269,883		239,728		84,347		76,240
Total	$	4,311,861	$	3,906,233	$	888,857	$	818,395

	At December 31, 2022
	Debt Securities Available				Debt Securities Held
	for Sale				to Maturity
	Amortized		Fair		Amortized		Fair
	Cost		Value		Cost		Value
	(In thousands)
Maturity in years:
1 year or less	$	251,578	$	250,317	$	12,676	$	12,659
Over 1 to 5 years		584,707		554,596		161,653		158,409
Over 5 to 10 years		2,869,559		2,570,159		636,733		605,081
Over 10 years		678,408		670,623		-		-
Subtotal		4,384,252		4,045,695		811,062		776,149
MBS		311,089		286,048		104,852		97,362
Total	$	4,695,341	$	4,331,743	$	915,914	$	873,511

Schedule of Unrealized Loss on Investments [Table Text Block]

	Debt Securities Available for Sale
	At September 30, 2023
	No. of		Less than 12 months					No. of		12 months or longer					No. of		Total
	Investment				Unrealized			Investment				Unrealized			Investment				Unrealized
	Positions		Fair Value		Losses			Positions		Fair Value		Losses			Positions		Fair Value		Losses
	($ in thousands)
Agency residential MBS		5	$	803	$	(26	)		108	$	238,914	$	(30,129	)		113	$	239,717	$	(30,155	)
Securities of U.S. Government sponsored entities		4		16,293		(365	)		19		263,071		(28,431	)		23		279,364		(28,796	)
Obligations of states and political subdivisions		8		8,887		(227	)		51		55,722		(3,752	)		59		64,609		(3,979	)
Corporate securities		-		-		-			152		1,799,419		(320,736	)		152		1,799,419		(320,736	)
Collateralized loan obligations		36		441,715		(12,234	)		67		594,769		(11,059	)		103		1,036,484		(23,293	)
Total		53	$	467,698	$	(12,852	)		397	$	2,951,895	$	(394,107	)		450	$	3,419,593	$	(406,959	)

	Debt Securities Held to Maturity
	At September 30, 2023
	No. of		Less than 12 months					No. of		12 months or longer					No. of		Total
	Investment				Unrecognized			Investment				Unrecognized			Investment				Unrecognized
	Positions		Fair Value		Losses			Positions		Fair Value		Losses			Positions		Fair Value		Losses
	($ in thousands)
Agency residential MBS		5	$	3	$	-			93	$	75,493	$	(8,116	)		98	$	75,496	$	(8,116	)
Obligations of states and political subdivisions		64		40,812		(1,109	)		28		27,638		(848	)		92		68,450		(1,957	)
Corporate securities		3		25,930		(1,792	)		48		640,619		(58,610	)		51		666,549		(60,402	)
Total		72	$	66,745	$	(2,901	)		169	$	743,750	$	(67,574	)		241	$	810,495	$	(70,475	)

	Debt Securities Available for Sale
	At December 31, 2022
	No. of		Less than 12 months					No. of		12 months or longer					No. of		Total
	Investment				Unrealized			Investment				Unrealized			Investment				Unrealized
	Positions		Fair Value		Losses			Positions		Fair Value		Losses			Positions		Fair Value		Losses
	($ in thousands)
Agency residential MBS		107	$	279,139	$	(24,222	)		9	$	6,110	$	(823	)		116	$	285,249	$	(25,045	)
Securities of U.S. Government sponsored entities		22		289,067		(15,486	)		-		-		-			22		289,067		(15,486	)
Obligations of states and political subdivisions		56		65,633		(1,902	)		8		3,265		(177	)		64		68,898		(2,079	)
Corporate securities		133		1,521,294		(170,453	)		56		555,727		(137,190	)		189		2,077,021		(307,643	)
Collateralized loan obligations		58		518,074		(13,772	)		20		192,692		(1,198	)		78		710,766		(14,970	)
Total		376	$	2,673,207	$	(225,835	)		93	$	757,794	$	(139,388	)		469	$	3,431,001	$	(365,223	)

	Debt Securities Held to Maturity
	At December 31, 2022
	No. of		Less than 12 months					No. of		12 months or longer					No. of		Total
	Investment				Unrecognized			Investment				Unrecognized			Investment				Unrecognized
	Positions		Fair Value		Losses			Positions		Fair Value		Losses			Positions		Fair Value		Losses
	($ in thousands)
Agency residential MBS		97	$	95,814	$	(7,404	)		2	$	682	$	(99	)		99	$	96,496	$	(7,503	)
Obligations of states and political subdivisions		54		53,536		(538	)		-		-		-			54		53,536		(538	)
Corporate securities		49		672,406		(34,448	)		-		-		-			49		672,406		(34,448	)
Total		200	$	821,756	$	(42,390	)		2	$	682	$	(99	)		202	$	822,438	$	(42,489	)

Debt Securities, Held-to-Maturity, Allowance for Credit Loss [Table Text Block]

	For the Nine Months Ended September 30,
	2023		2022
	(In thousands)
Allowance for credit losses:
Beginning balance	$	1	$	7
Provision		-		-
Chargeoffs		-		-
Recoveries		-		-
Total ending balance	$	1	$	7

Interest Income from Investments [Table Text Block]

	For the Three Months				For the Nine Months
	Ended September 30,
	2023		2022		2023		2022
	(In thousands)
Taxable	$	55,911	$	44,461	$	166,031	$	105,286
Tax-exempt from federal income tax		1,083		1,391		3,439		4,568
Total interest income from investment securities	$	56,994	$	45,852	$	169,470	$	109,854