Debt Securities Available-for-Sale (Tables)

6 Months Ended

Jun. 30, 2021

Investments, Debt and Equity Securities [Abstract]

Comparative Summary of Mortgage-Backed Securities and Other Securities Available-for-Sale

The following is a comparative summary of mortgage-backed and other debt securities available-for-sale at June 30, 2021, and December 31, 2020 (in thousands):

	June 30, 2021
			Gross		Gross		Estimated
	Amortized		unrealized		unrealized		fair
	cost		gains		losses		value
U.S. Government agency securities	$	2,758	$	—	$	(4)	$	2,754
Mortgage-backed securities:
Pass-through certificates:
Government sponsored enterprises ("GSEs")	221,513		8,640		(386)		229,767
Real estate mortgage investment conduits ("REMICs"):
GSE	735,021		5,859		(502)		740,378
	956,534		14,499		(888)		970,145
Other debt securities:
Municipal bonds	77		1		—		78
Corporate bonds	123,678		815		(47)		124,446
	123,755		816		(47)		124,524
Total debt securities available-for-sale	$	1,083,047	$	15,315	$	(939)	$	1,097,423

	December 31, 2020
			Gross		Gross		Estimated
	Amortized		unrealized		unrealized		fair
	cost		gains		losses		value
U.S. Government agency securities	$	3,168	$	—	$	(10)	$	3,158
Mortgage-backed securities:
Pass-through certificates:
GSE	270,867		10,720		(244)		281,343
REMICs:
GSE	884,414		7,027		(476)		890,965
Non-GSE	4		—		—		4
	1,155,285		17,747		(720)		1,172,312
Other debt securities:
Municipal bonds	122		1		—		123
Corporate bonds	87,319		1,099		—		88,418
Asset-backed securities	779		15		—		794
	88,220		1,115		—		89,335
Total debt securities available-for-sale	$	1,246,673	$	18,862	$	(730)	$	1,264,805

Summary of Expected Maturity Distribution of Debt Securities Available-for-Sale, Other Than Mortgage-Backed Securities

The following is a summary of the expected maturity distribution of debt securities available-for-sale, other than mortgage-backed securities, at June 30, 2021 (in thousands):

Available-for-sale	Amortized cost		Estimated fair value
Due in one year or less	$	35,282	$	35,757
Due after one year through five years	73,463		73,804
Due after five years through ten years	17,768		17,717
	$	126,513	$	127,278

Gross Unrealized Losses on Mortgage-Backed Securities

Gross unrealized losses on mortgage-backed and other debt securities available-for-sale, and the estimated fair value of the related securities, aggregated by security category and length of time that individual securities have been in a continuous unrealized loss position, at June 30, 2021, and December 31, 2020, were as follows (in thousands):

	June 30, 2021
	Less than 12 months				12 months or more				Total
	Unrealized		Estimated		Unrealized		Estimated		Unrealized		Estimated
	losses		fair value		losses		fair value		losses		fair value
U.S. Government agency securities	$	(4)	$	2,754	$	—	$	—	$	(4)	$	2,754
Mortgage-backed securities:
Pass-through certificates:
GSE	(378)		31,540		(8)		383		(386)		31,923
REMICs:
GSE	(502)		124,255		—		—		(502)		124,255
Other debt securities:
Corporate bonds	(47)		14,964		—		—		(47)		14,964
Total	$	(931)	$	173,513	$	(8)	$	383	$	(939)	$	173,896

	December 31, 2020
	Less than 12 months				12 months or more				Total
	Unrealized		Estimated		Unrealized		Estimated		Unrealized		Estimated
	losses		fair value		losses		fair value		losses		fair value
U.S. Government agency securities	$	(10)	$	3,158	$	—	$	—	$	(10)	$	3,158
Mortgage-backed securities:
Pass-through certificates:
GSE	(233)		28,419		(11)		459		(244)		28,878
REMICs:
GSE	(476)		210,569		—		—		(476)		210,569
Total	$	(719)	$	242,146	$	(11)	$	459	$	(730)	$	242,605