Debt Securities Available for Sale (Tables)

9 Months Ended

Sep. 30, 2024

Investments, Debt and Equity Securities [Abstract]

Schedule of Debt Securities, Available-for-Sale

Debt securities available for sale at September 30, 2024 and December 31, 2023 are summarized as follows:

	September 30, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
	(In thousands)
U.S. government and agency obligations	$	272,913	$	3,690	$	(1,133)	$	275,470
Mortgage-backed securities and collateralized mortgage obligations	1,022,232		809		(113,471)		909,570
Municipal obligations	2,845		—		(27)		2,818
Corporate debt securities	97,512		27		(12,933)		84,606
	$	1,395,502	$	4,526	$	(127,564)	$	1,272,464

	December 31, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
			(In thousands)
U.S. government and agency obligations	$	146,387	$	924	$	(1,810)	$	145,501
Mortgage-backed securities and collateralized mortgage obligations	1,009,508		20		(141,943)		867,585
Municipal obligations	2,770		—		(68)		2,702
Corporate debt securities	92,565		2		(14,798)		77,769
	$	1,251,230	$	946	$	(158,619)	$	1,093,557

Schedule of Securities by Contractual Maturity

The amortized cost and fair value of debt securities available for sale at September 30, 2024, by contractual final maturity, is shown below. Expected maturities may differ from contractual maturities due to prepayment or early call options exercised by the issuer.

	September 30, 2024
	Amortized Cost		Fair Value
	(In thousands)
One year or less	$	99,641	$	99,662
More than one year to five years	195,370		196,775
More than five years to ten years	78,259		66,457
	$	373,270	$	362,894
Mortgage-backed securities and collateralized mortgage obligations	1,022,232		909,570
	$	1,395,502	$	1,272,464

The amortized cost and fair value of debt securities held to maturity at September 30, 2024, by contractual final maturity, is shown below. Expected maturities may differ from contractual maturities due to prepayment or early call options exercised by the issuer.

	September 30, 2024
	Amortized Cost		Fair Value
	(In thousands)
More than one year to five years	$	24,875	$	23,438
More than five years to ten years	9,997		8,975
More than ten years	10,000		8,080
	44,872		40,493
Mortgage-backed securities and collateralized mortgage obligations	356,459		327,066
	$	401,331	$	367,559

Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value

The following tables summarize the fair value and gross unrealized losses of those securities that reported an unrealized loss at September 30, 2024 and December 31, 2023 and if the unrealized loss position was continuous for the twelve months prior to those respective dates:

6.    Debt Securities Available for Sale (continued)

	September 30, 2024
	Less Than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized (Losses)		Fair Value		Gross Unrealized (Losses)		Fair Value		Gross Unrealized (Losses)
	(In thousands)
U.S. government and agency obligations	$	—	$	—	$	21,080	$	(1,133)	$	21,080	$	(1,133)
Mortgage-backed securities and collateralized mortgage obligations	9,993		(4)		813,803		(113,467)		823,796		(113,471)
Municipal obligations	1,010		(1)		1,809		(26)		2,819		(27)
Corporate debt securities	—		—		79,578		(12,933)		79,578		(12,933)
	$	11,003	$	(5)	$	916,270	$	(127,559)	$	927,273	$	(127,564)

	December 31, 2023
	Less Than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized (Losses)		Fair Value		Gross Unrealized (Losses)		Fair Value		Gross Unrealized (Losses)
	(In thousands)
U.S. government and agency obligations	$	—	$	—	$	21,344	$	(1,810)	$	21,344	$	(1,810)
Mortgage-backed securities and collateralized mortgage obligations	54		(4)		863,026		(141,939)		863,080		(141,943)
Municipal obligations	—		—		2,702		(68)		2,702		(68)
Corporate debt securities	—		—		75,765		(14,798)		75,765		(14,798)
	$	54	$	(4)	$	962,837	$	(158,615)	$	962,891	$	(158,619)