Note 3 - Investment Securities (Tables)

6 Months Ended

Jun. 30, 2020

Notes Tables

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

	At June 30, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
	(In thousands)
Debt securities available for sale
Agency residential mortgage-backed securities ("MBS")	$	811,331	$	28,755	$	(1	)	$	840,085
Agency commercial MBS		3,638		-		(9	)		3,629
Securities of U.S. Government entities		171		-		-			171
Obligations of states and political subdivisions		147,260		4,932		(38	)		152,154
Corporate securities		2,170,503		100,018		(1,110	)		2,269,411
Commercial paper		299,742		45		(205	)		299,582
Collateralized Loan Obligations		142,652		738		(52	)		143,338
Total debt securities available for sale		3,575,297		134,488		(1,415	)		3,708,370
Debt securities held to maturity
Agency residential MBS		304,439		9,364		(45	)		313,758
Non-agency residential MBS		2,112		14		-			2,126
Obligations of states and political subdivisions		331,746		8,760		-			340,506
Total debt securities held to maturity		638,297		18,138		(45	)		656,390
Total	$	4,213,594	$	152,626	$	(1,460	)	$	4,364,760

	At December 31, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
	(In thousands)
Debt securities available for sale
U.S. Treasury securities	$	19,999	$	1	$	-		$	20,000
Securities of U.S. Government sponsored entities		111,251		14		(98	)		111,167
Agency residential mortgage-backed securities (MBS)		934,592		10,996		(5,838	)		939,750
Agency commercial MBS		3,711		-		(3	)		3,708
Securities of U.S. Government entities		553		-		(9	)		544
Obligations of states and political subdivisions		159,527		3,656		(44	)		163,139
Corporate securities		1,805,479		29,183		(879	)		1,833,783
Collateralized Loan Obligations		6,748		7		-			6,755
Total debt securities available for sale		3,041,860		43,857		(6,871	)		3,078,846
Debt securities held to maturity
Agency residential MBS		353,937		766		(2,235	)		352,468
Non-agency residential MBS		2,354		22		-			2,376
Obligations of states and political subdivisions		381,781		7,672		(1	)		389,452
Total debt securities held to maturity		738,072		8,460		(2,236	)		744,296
Total	$	3,779,932	$	52,317	$	(9,107	)	$	3,823,142

Investments Classified by Contractual Maturity Date [Table Text Block]

	At June 30, 2020
	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	$	528,253	$	529,421	$	57,015	$	57,392
Over 1 to 5 years		1,062,469		1,116,754		146,003		149,824
Over 5 to 10 years		1,142,837		1,190,058		128,728		133,290
Over 10 years		26,769		28,423		-		-
Subtotal		2,760,328		2,864,656		331,746		340,506
MBS		814,969		843,714		306,551		315,884
Total	$	3,575,297	$	3,708,370	$	638,297	$	656,390

	At December 31, 2019
	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	$	294,698	$	295,255	$	70,378	$	70,602
Over 1 to 5 years		1,104,775		1,122,391		161,911		165,126
Over 5 to 10 years		670,595		683,277		149,492		153,724
Over 10 years		33,489		34,465		-		-
Subtotal		2,103,557		2,135,388		381,781		389,452
MBS		938,303		943,458		356,291		354,844
Total	$	3,041,860	$	3,078,846	$	738,072	$	744,296

Schedule of Unrealized Loss on Investments [Table Text Block]

	Debt Securities Available for Sale
	At June 30, 2020
	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		-	$	-	$	-			2	$	337	$	(1	)		2	$	337	$	(1	)
Agency commercial MBS		1		3,629		(9	)		-		-		-			1		3,629		(9	)
Securities of U.S. Government entities		1		171		-			-		-		-			1		171		-
Obligations of states and political subdivisions		-		-		-			2		2,169		(38	)		2		2,169		(38	)
Corporate securities		5		44,582		(749	)		4		20,409		(361	)		9		64,991		(1,110	)
Commercial paper		6		149,670		(205	)		-		-		-			6		149,670		(205	)
Collateralized Loan Obligations		3		28,812		(52	)		-		-		-			3		28,812		(52	)
Total		16	$	226,864	$	(1,015	)		8	$	22,915	$	(400	)		24	$	249,779	$	(1,415	)

	Debt Securities Held to Maturity
	At June 30, 2020
	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		3	$	179	$	-		4	$	1,883	$	(45	)		7	$	2,062	$	(45	)
Non-agency residential MBS		1		507		-		-		-		-			1		507		-
Total		4	$	686	$	-		4	$	1,883	$	(45	)		8	$	2,569	$	(45	)

	Debt Securities Available for Sale
	At December 31, 2019
	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)
Securities of U.S. Government sponsored entities		1	$	9,951	$	(49	)		3	$	45,877	$	(49	)		4	$	55,828	$	(98	)
Agency residential MBS		6		11,674		(100	)		47		347,384		(5,738	)		53		359,058		(5,838	)
Agency commercial MBS		1		3,708		(3	)		-		-		-			1		3,708		(3	)
Securities of U.S. Government entities		-		-		-			2		544		(9	)		2		544		(9	)
Obligations of states and political subdivisions		-		-		-			7		4,163		(44	)		7		4,163		(44	)
Corporate securities		8		71,577		(162	)		11		64,380		(717	)		19		135,957		(879	)
Total		16	$	96,910	$	(314	)		70	$	462,348	$	(6,557	)		86	$	559,258	$	(6,871	)

	Debt Securities Held to Maturity
	At December 31, 2019
	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		6	$	12,098	$	(87	)		54	$	277,203	$	(2,148	)		60	$	289,301	$	(2,235	)
Obligations of states and political subdivisions		-		-		-			1		251		(1	)		1		251		(1	)
Total		6	$	12,098	$	(87	)		55	$	277,454	$	(2,149	)		61	$	289,552	$	(2,236	)

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

	For
	the Six Months
	Ended June 30,
	2020
	(In thousands)
Allowance for credit losses:
Beginning balance, prior to adoption of ASU 2016-13	$	-
Impact of adopting ASU 2016-13		16
Provision		-
Chargeoffs		-
Recoveries		-
Total ending balance	$	16

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

	Credit Risk Profile by Credit Rating
	At June 30, 2020
	(In thousands)
	AAA/AA/A		BBB		BB/B		Total
Agency residential MBS	$	304,439	$	-	$	-	$	304,439
Non-agency residential MBS		1,082		-		1,030		2,112
Obligations of states and political subdivisions		331,645		101		-		331,746
Total	$	637,166	$	101	$	1,030	$	638,297

Interest Income from Investments [Table Text Block]

	For the Three Months				For the Six Months
	Ended June 30,
	2020		2019		2020		2019
	(In thousands)
Taxable	$	22,920	$	18,773	$	44,884	$	37,406
Tax-exempt from regular federal income tax		3,228		4,073		6,590		8,388
Total interest income from investment securities	$	26,148	$	22,846	$	51,474	$	45,794