Investment Securities Available for Sale (Tables)

12 Months Ended

Dec. 31, 2022

Summary of Available-for-Sale Investment Securities

The amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities available for sale at December 31, 2022 and 2021 are summarized below.


	December 31, 2022
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	515,953	$	—	$	(44,140)	$	471,813
U.S. Government agency securities	52,411		—		(3,613)		48,798
Mortgage-backed securities issued by U.S. Government agencies	904,593		1,624		(113,468)		792,749
Mortgage-backed securities issued by U.S. Government sponsored enterprises	8,144,374		936		(1,250,240)		6,895,070
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	769,498		—		(114,371)		655,127
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	877,590		—		(71,645)		805,945

Corporate debt securities and other debt securities	8,908		—		(307)		8,601
Total investment securities available for sale	$	11,273,327	$	2,560	$	(1,597,784)	$	9,678,103

	December 31, 2021
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	120,465	$	—	$	(2,627)	$	117,838
U.S. Government agency securities	53,214		1,374		(387)		54,201
Mortgage-backed securities issued by U.S. Government agencies	790,329		768		(11,464)		779,633
Mortgage-backed securities issued by U.S. Government sponsored enterprises	8,063,890		50,491		(102,080)		8,012,301
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	951,691		4,658		(16,726)		939,623
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	479,420		8,644		(6,320)		481,744
Asset-backed securities	514,188		—		—		514,188
Corporate debt securities and other debt securities	18,309		492		—		18,801
Total investment securities available for sale	$	10,991,506	$	66,427	$	(139,604)	$	10,918,329

Schedule of Unrealized Loss on Investments

Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2022 and December 31, 2021 are presented below.


	December 31, 2022
	Less than 12 Months				12 Months or Longer				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury securities	$	139,737	$	(6,789)	$	307,582	$	(37,351)	$	447,319	$	(44,140)
U.S. Government agency securities	28,938		(1,053)		19,603		(2,560)		48,541		(3,613)
Mortgage-backed securities issued by U.S. Government agencies	187,655		(5,952)		521,395		(107,516)		709,050		(113,468)
Mortgage-backed securities issued by U.S. Government sponsored enterprises	1,473,348		(120,135)		5,365,233		(1,130,105)		6,838,581		(1,250,240)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	119,649		(10,311)		535,478		(104,060)		655,127		(114,371)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	565,382		(29,383)		240,564		(42,262)		805,946		(71,645)
Corporate debt securities and other debt securities	8,601		(307)		—		—		8,601		(307)
Total	$	2,523,310	$	(173,930)	$	6,989,855	$	(1,423,854)	$	9,513,165	$	(1,597,784)

	December 31, 2021
	Less than 12 Months				12 Months or Longer				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury securities	$	49,648	$	(379)	$	47,590	$	(2,248)	$	97,238	$	(2,627)
U.S. Government agency securities	21,760		(387)		—		—		21,760		(387)
Mortgage-backed securities issued by U.S. Government agencies	461,078		(5,858)		244,264		(5,606)		705,342		(11,464)
Mortgage-backed securities issued by U.S. Government sponsored enterprises	5,729,476		(82,671)		643,758		(19,409)		6,373,234		(102,080)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	187,431		(3,981)		504,238		(12,745)		691,669		(16,726)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	146,672		(2,951)		83,533		(3,369)		230,205		(6,320)

Total	$	6,596,065	$	(96,227)	$	1,523,383	$	(43,377)	$	8,119,448	$	(139,604)

Amortized Cost and Estimated Fair Value by Contractual Maturity of Investment Securities Available-for-Sale

The amortized cost and fair value by contractual maturity of investment securities available for sale at December 31, 2022 are shown below. The expected life of MBSs or CMOs may differ from contractual maturities because issuers may have the

right to call or prepay obligations with or without call or prepayment penalties. For purposes of the maturity table, MBSs and CMOs, which are not due at a single maturity date, have been classified based on the final contractual maturity date.


	Distribution of Maturities at December 31, 2022
(in thousands)	Within One Year		1 to 5 Years		5 to 10 Years		More Than 10 Years		Total
Amortized Cost
U.S. Treasury securities	$	24,293	$	441,804	$	49,856	$	—	$	515,953
U.S. Government agency securities	273		22,148		29,990		—		52,411
Mortgage-backed securities issued by U.S. Government agencies	—		534		4		904,055		904,593
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		4,659		109,583		8,030,132		8,144,374
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		91		12,293		757,114		769,498
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	—		573,334		238,228		66,028		877,590

Corporate debt securities and other debt securities	—		8,908		—		—		8,908
Total amortized cost	$	24,566	$	1,051,478	$	439,954	$	9,757,329	$	11,273,327

Fair Value
U.S. Treasury securities	$	24,293	$	407,430	$	40,090	$	—	$	471,813
U.S. Government agency securities	273		19,588		28,937		—		48,798
Mortgage-backed securities issued by U.S. Government agencies	—		517		4		792,228		792,749
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		4,451		102,400		6,788,219		6,895,070
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		88		11,808		643,231		655,127
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	—		540,820		203,757		61,368		805,945

Corporate debt securities and other debt securities	—		8,601		—		—		8,601
Total fair value	$	24,566	$	981,495	$	386,996	$	8,285,046	$	9,678,103

Summary of Sales Transactions in the Investment Securities Available-for-Sale Portfolio

Gross gains and gross losses on sales of securities available for sale for the years ended December 31, 2022, 2021, and 2020 are presented below. The specific identification method is used to reclassify gains and losses out of other comprehensive income (loss) at the time of sale.


(in thousands)	2022		2021		2020
Gross realized gains on sales	$	—	$	1,191	$	85,375
Gross realized losses on sales	—		(1,990)		(6,444)
Investment securities gains (losses), net	$	—	$	(799)	$	78,931