Investment Securities Available for Sale (Tables)

3 Months Ended

Mar. 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 March 31, 2022 and December 31, 2021 are summarized below.


	March 31, 2022
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	414,397	$	—	$	(19,811)	$	394,586
U.S. Government agency securities	52,865		411		(1,471)		51,805
Mortgage-backed securities issued by U.S. Government agencies	733,289		60		(46,605)		686,744
Mortgage-backed securities issued by U.S. Government sponsored enterprises	8,169,609		4,937		(553,915)		7,620,631
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	877,362		326		(54,810)		822,878
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	554,868		1,020		(25,092)		530,796
Asset-backed securities	337,037		—		—		337,037
Corporate debt securities and other debt securities	18,333		291		—		18,624
Total investment securities available for sale	$	11,157,760	$	7,045	$	(701,704)	$	10,463,101

	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 Gross Unrealized Losses on Investment Securities and Fair Value

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 March 31, 2022 and December 31, 2021 are presented below.


	March 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	$	328,920	$	(14,282)	$	44,313	$	(5,529)	$	373,233	$	(19,811)
U.S. Government agency securities	20,691		(1,471)		—		—		20,691		(1,471)
Mortgage-backed securities issued by U.S. Government agencies	316,662		(19,328)		365,096		(27,277)		681,758		(46,605)
Mortgage-backed securities issued by U.S. Government sponsored enterprises	5,225,550		(365,535)		1,966,572		(188,380)		7,192,122		(553,915)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	366,174		(18,823)		441,167		(35,987)		807,341		(54,810)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	224,955		(8,847)		146,528		(16,245)		371,483		(25,092)
Total	$	6,482,952	$	(428,286)	$	2,963,676	$	(273,418)	$	9,446,628	$	(701,704)

	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

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 March 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	$	21,353	$	343,202	$	49,842	$	—	$	414,397
U.S. Government agency securities	455		273		52,137		—		52,865
Mortgage-backed securities issued by U.S. Government agencies	—		835		—		732,454		733,289
Mortgage-backed securities issued by U.S. Government sponsored enterprises	11		—		136,502		8,033,096		8,169,609
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		129		—		877,233		877,362
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	—		251,596		225,872		77,400		554,868
Asset-backed securities	337,037		—		—		—		337,037
Corporate debt securities and other debt securities	9,501		—		8,832		—		18,333
Total amortized cost	$	368,357	$	596,035	$	473,185	$	9,720,183	$	11,157,760

Fair Value
U.S. Treasury securities	$	21,353	$	328,920	$	44,313	$	—	$	394,586
U.S. Government agency securities	462		275		51,068		—		51,805
Mortgage-backed securities issued by U.S. Government agencies	—		845		—		685,899		686,744
Mortgage-backed securities issued by U.S. Government sponsored enterprises	11		—		134,665		7,485,955		7,620,631
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		130		—		822,748		822,878
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	—		244,983		209,622		76,191		530,796
Asset-backed securities	337,037		—		—		—		337,037
Corporate debt securities and other debt securities	9,506		—		9,118		—		18,624
Total fair value	$	368,369	$	575,153	$	448,786	$	9,070,793	$	10,463,101

Schedule of Sales Activities of Available-for-Sale Securities

Gross gains and gross losses on sales of securities available for sale for the three months ended March 31, 2022 and 2021 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.


	Three Months Ended March 31,
(in thousands)	2022		2021
Gross realized gains on sales	$	—	$	—
Gross realized losses on sales	—		(1,990)
Investment securities gains (losses), net	$	—	$	(1,990)