Note 3 - Investment Securities (Tables)

6 Months Ended

Jun. 30, 2024

Notes Tables

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

	At June 30, 2024
			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
	(In thousands)
Debt securities available for sale:
Agency residential mortgage-backed securities ("MBS")	$	243,230	$	1	$	(20,425	)	$	222,806
Securities of U.S. Government sponsored entities		309,985		-		(18,779	)		291,206
U.S. Treasury Securities		4,820		-		-			4,820
Obligations of states and political subdivisions		72,192		4		(2,438	)		69,758
Corporate securities		2,084,391		356		(229,129	)		1,855,618
Collateralized loan obligations		1,264,811		468		(10,169	)		1,255,110
Total debt securities available for sale		3,979,429		829		(280,940	)		3,699,318
Debt securities held to maturity:
Agency residential MBS		67,777		17		(5,219	)		62,575
Obligations of states and political subdivisions		61,043		7		(802	)		60,248
Corporate securities		732,049		-		(37,801	)		694,248
Total debt securities held to maturity		860,869		24		(43,822	)		817,071
Total	$	4,840,298	$	853	$	(324,762	)	$	4,516,389

	At December 31, 2023
			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
	(In thousands)
Debt securities available for sale:
Agency residential MBS	$	258,150	$	6	$	(18,702	)	$	239,454
Securities of U.S. Government sponsored entities		308,768		2		(13,851	)		294,919
Obligations of states and political subdivisions		72,679		42		(1,438	)		71,283
Corporate securities		2,129,103		480		(220,035	)		1,909,548
Collateralized loan obligations		1,501,248		830		(17,481	)		1,484,597
Total debt securities available for sale		4,269,948		1,360		(271,507	)		3,999,801
Debt securities held to maturity:
Agency residential MBS		78,565		17		(5,270	)		73,312
Obligations of states and political subdivisions		71,182		47		(335	)		70,894
Corporate securities		728,650		84		(23,378	)		705,356
Total debt securities held to maturity		878,397		148		(28,983	)		849,562
Total	$	5,148,345	$	1,508	$	(300,490	)	$	4,849,363

Investments Classified by Contractual Maturity Date [Table Text Block]

	At June 30, 2024
	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	$	122,825	$	121,872	$	12,626	$	12,568
Over 1 to 5 years		869,312		817,287		356,026		346,397
Over 5 to 10 years		1,479,251		1,282,243		424,440		395,531
Subtotal		2,471,388		2,221,402		793,092		754,496
Collateralized loan obligations		1,264,811		1,255,110		-		-
Agency residential MBS		243,230		222,806		67,777		62,575
Total	$	3,979,429	$	3,699,318	$	860,869	$	817,071

	At December 31, 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	$	52,703	$	52,357	$	15,117	$	15,095
Over 1 to 5 years		756,658		721,179		312,847		307,557
Over 5 to 10 years		1,701,189		1,502,214		471,868		453,598
Subtotal		2,510,550		2,275,750		799,832		776,250
Collateralized loan obligations		1,501,248		1,484,597		-		-
Agency residential MBS		258,150		239,454		78,565		73,312
Total	$	4,269,948	$	3,999,801	$	878,397	$	849,562

Schedule of Unrealized Loss on Investments 1 [Table Text Block]

	Debt Securities Available for Sale
	At June 30, 2024
	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		1	$	498	$	(8	)		105	$	213,122	$	(20,417	)		106	$	213,620	$	(20,425	)
Securities of U.S. Government sponsored entities		2		6,842		(89	)		21		284,364		(18,690	)		23		291,206		(18,779	)
U.S. Treasury securities		1		4,820		-			-		-		-			1		4,820		-
Obligations of states and political subdivisions		4		4,698		(51	)		51		57,076		(2,387	)		55		61,774		(2,438	)
Corporate securities		-		-		-			144		1,843,918		(229,129	)		144		1,843,918		(229,129	)
Collateralized loan obligations		14		143,567		(1,214	)		49		506,511		(8,955	)		63		650,078		(10,169	)
Total		22	$	160,425	$	(1,362	)		370	$	2,904,991	$	(279,578	)		392	$	3,065,416	$	(280,940	)

	Debt Securities Held to Maturity
	At June 30, 2024
	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		-	$	-	$	-			80	$	61,517	$	(5,219	)		80	$	61,517	$	(5,219	)
Obligations of states and political subdivisions		31		17,928		(164	)		38		35,328		(638	)		69		53,256		(802	)
Corporate securities		4		36,339		(907	)		48		657,909		(36,894	)		52		694,248		(37,801	)
Total		35	$	54,267	$	(1,071	)		166	$	754,754	$	(42,751	)		201	$	809,021	$	(43,822	)

	Debt Securities Available for Sale
	At December 31, 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		1	$	115	$	(2	)		107	$	238,642	$	(18,700	)		108	$	238,757	$	(18,702	)
Securities of U.S. Government sponsored entities		2		9,746		(15	)		19		278,265		(13,836	)		21		288,011		(13,851	)
Obligations of states and political subdivisions		2		2,280		(15	)		50		57,614		(1,423	)		52		59,894		(1,438	)
Corporate securities		-		-		-			151		1,894,602		(220,035	)		151		1,894,602		(220,035	)
Collateralized loan obligations		34		428,363		(8,914	)		67		578,643		(8,567	)		101		1,007,006		(17,481	)
Total		39	$	440,504	$	(8,946	)		394	$	3,047,766	$	(262,561	)		433	$	3,488,270	$	(271,507	)

	Debt Securities Held to Maturity
	At December 31, 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		1	$	-	$	-			93	$	72,376	$	(5,270	)		94	$	72,376	$	(5,270	)
Obligations of states and political subdivisions		23		18,599		(90	)		26		25,466		(245	)		49		44,065		(335	)
Corporate securities		3		26,567		(1,184	)		46		641,598		(22,194	)		49		668,165		(23,378	)
Total		27	$	45,166	$	(1,274	)		165	$	739,440	$	(27,709	)		192	$	784,606	$	(28,983	)

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

	For the Six Months Ended June 30,
	2024		2023
	(In thousands)
Allowance for credit losses:
Beginning balance	$	1	$	1
Provision		-		-
Chargeoffs		-		-
Recoveries		-		-
Total ending balance	$	1	$	1

Debt Securities, Held-to-Maturity, Credit Quality Indicator [Table Text Block]

	Credit Risk Profile by Credit Rating
	At June 30, 2024
	AAA/AA/A		BBB+		Not Rated		Total
	(In thousands)
Agency residential MBS	$	67,271	$	-	$	506	$	67,777
Obligations of states and political subdivisions		60,318		-		725		61,043
Corporate securities		527,065		204,984		-		732,049
Total	$	654,654	$	204,984	$	1,231	$	860,869

Interest Income from Investments [Table Text Block]

	For the Three Months				For the Six Months
	Ended June 30,
	2024		2023		2024		2023
	(In thousands)
Taxable	$	51,804	$	55,371	$	105,949	$	110,120
Tax-exempt from regular federal income tax		953		1,163		1,947		2,356
Total interest income from investment securities	$	52,757	$	56,534	$	107,896	$	112,476