Debt Securities Available for Sale (Tables)

3 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of amortized cost, gross unrealized gains, gross unrealized losses and the fair value of securities available-for-sale

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

	March 31, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
	(In thousands)
U.S. government and agency obligations	$	23,432	$	—	$	(1,793)	$	21,639
Mortgage-backed securities and collateralized mortgage obligations	1,324,035		179		(153,341)		1,170,873
Municipal obligations	3,695		—		(147)		3,548
Corporate debt securities	92,539		—		(16,029)		76,510
	$	1,443,701	$	179	$	(171,310)	$	1,272,570

	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

Schedule of securities by contractual maturity

The amortized cost and fair value of debt securities available for sale at March 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.

	March 31, 2023
	Amortized Cost		Fair Value
	(In thousands)
One year or less	$	920	$	906
More than one year to five years	54,882		50,274
More than five years to ten years	63,864		50,517
	$	119,666	$	101,697
Mortgage-backed securities and collateralized mortgage obligations	1,324,035		1,170,873
	$	1,443,701	$	1,272,570

The amortized cost and fair value of debt securities held to maturity at March 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.

	March 31, 2023
	Amortized Cost		Fair Value
	(In thousands)
More than one year to five years	$	19,875	$	18,600
More than five years to ten years	19,996		17,018
More than ten years	10,000		7,654
	49,871		43,272
Mortgage-backed securities and collateralized mortgage obligations	367,356		328,915
	$	417,227	$	372,187

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

	March 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	$	1,408	$	(53)	$	20,231	$	(1,740)	$	21,639	$	(1,793)
Mortgage-backed securities and collateralized mortgage obligations	87,503		(3,544)		1,060,893		(149,797)		1,148,396		(153,341)
Municipal obligations	3,111		(136)		438		(11)		3,549		(147)
Corporate debt securities	17,309		(5,191)		57,201		(10,838)		74,510		(16,029)
	$	109,331	$	(8,924)	$	1,138,763	$	(162,386)	$	1,248,094	$	(171,310)

6.    Debt Securities Available for Sale (continued)

	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 three months ended March 31, 2023 and 2022:

	Three Months Ended March 31,
	2023		2022
	(In thousands)
Allowance for Credit Losses:
Beginning balance	$	—	$	—
Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022	—		490
Provision for credit losses	—		654
Ending balance	$	—	$	1,144