Debt Securities Available for Sale (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Debt securities, available-for-sale

Debt securities available for sale at December 31, 2023 and 2022 are summarized as follows:

	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

	December 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
			(In thousands)
U.S. government and agency obligations	$	67,771	$	—	$	(4,205)	$	63,566
Mortgage-backed securities and collateralized mortgage obligations	1,351,929		135		(170,337)		1,181,727
Municipal obligations	3,697		—		(122)		3,575
Corporate debt securities	92,544		6		(12,784)		79,766
	$	1,515,941	$	141	$	(187,448)	$	1,328,634

Investments classified by contractual maturity date

The amortized cost and fair value of debt securities available for sale at December 31, 2023, 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.

	December 31, 2023
	Amortized Cost		Fair Value
	(In thousands)
One year or less	$	50,854	$	50,924
More than one year to five years	122,038		119,556
More than five years to ten years	68,830		55,492
	$	241,722	$	225,972
Mortgage-backed securities and collateralized mortgage obligations	1,009,508		867,585
	$	1,251,230	$	1,093,557

Expected maturities may differ from contractual maturities due to prepayment or early call options exercised by the issuer.

	December 31, 2023
	Amortized Cost		Fair Value
	(In thousands)
More than one year to five years	$	29,875	$	27,723
More than five years to ten years	9,996		8,661
More than ten years	10,000		7,585
	49,871		43,969
Mortgage-backed securities and collateralized mortgage obligations	351,283		313,208
	$	401,154	$	357,177

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 December 31, 2023 and 2022 and if the unrealized loss position was continuous for the twelve months prior to those respective dates:

	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)

	December 31, 2022
	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	$	47,956	$	(2,359)	$	15,610	$	(1,846)	$	63,566	$	(4,205)
Mortgage-backed securities and collateralized mortgage obligations	424,328		(29,013)		741,515		(141,324)		1,165,843		(170,337)
Municipal obligations	3,574		(122)		—		—		3,574		(122)
Corporate debt securities	46,751		(5,792)		31,008		(6,992)		77,759		(12,784)
	$	522,609	$	(37,286)	$	788,133	$	(150,162)	$	1,310,742	$	(187,448)

Debt securities, available-for-sale, allowance for credit loss

The following table presents the activity in the allowance for credit losses on debt securities available for sale for the years ended December 31, 2023 and 2022:

	December 31,
	2023		2022
	(In thousands)
Allowance for Credit Losses:
Beginning balance	$	—	$	—
Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022	—		490
(Reversal of) credit losses	—		(490)
Ending balance	$	—	$	—