Investment Securities Available for Sale (Tables)

3 Months Ended

Mar. 31, 2023

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, 2023 and December 31, 2022 are summarized below.


	March 31, 2023
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	516,782	$	—	$	(36,502)	$	480,280
U.S. Government agency securities	52,397		1		(3,453)		48,945
Mortgage-backed securities issued by U.S. Government agencies	810,042		202		(101,699)		708,545
Mortgage-backed securities issued by U.S. Government sponsored enterprises	8,159,830		2,791		(1,137,121)		7,025,500
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	753,877		—		(105,318)		648,559
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	873,930		—		(61,907)		812,023

Corporate debt securities and other debt securities	8,933		—		(167)		8,766
Total investment securities available for sale	$	11,175,791	$	2,994	$	(1,446,167)	$	9,732,618

	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

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, 2023 and December 31, 2022 are presented below.


	March 31, 2023
	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	$	94,424	$	(2,869)	$	361,097	$	(33,633)	$	455,521	$	(36,502)
U.S. Government agency securities	28,845		(1,146)		19,841		(2,307)		48,686		(3,453)
Mortgage-backed securities issued by U.S. Government agencies	119,866		(1,730)		538,765		(99,969)		658,631		(101,699)
Mortgage-backed securities issued by U.S. Government sponsored enterprises	699,851		(31,589)		6,038,186		(1,105,532)		6,738,037		(1,137,121)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	11,850		(335)		636,709		(104,983)		648,559		(105,318)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	380,458		(12,586)		431,565		(49,321)		812,023		(61,907)
Corporate debt securities and other debt securities	8,766		(167)		—		—		8,766		(167)
Total	$	1,344,060	$	(50,422)	$	8,026,163	$	(1,395,745)	$	9,370,223	$	(1,446,167)

	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)

Schedule of 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, 2023
(in thousands)	Within One Year		1 to 5 Years		5 to 10 Years		More Than 10 Years		Total
Amortized Cost
U.S. Treasury securities	$	24,560	$	442,362	$	49,860	$	—	$	516,782
U.S. Government agency securities	258		22,148		29,991		—		52,397
Mortgage-backed securities issued by U.S. Government agencies	—		454		4		809,584		810,042
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		20,872		87,576		8,051,382		8,159,830
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		80		11,932		741,865		753,877
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	—		585,636		222,838		65,456		873,930

Corporate debt securities and other debt securities	—		8,933		—		—		8,933
Total amortized cost	$	24,818	$	1,080,485	$	402,201	$	9,668,287	$	11,175,791

Fair Value
U.S. Treasury securities	$	24,560	$	414,370	$	41,350	$	—	$	480,280
U.S. Government agency securities	259		19,841		28,845		—		48,945
Mortgage-backed securities issued by U.S. Government agencies	—		441		4		708,100		708,545
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		19,951		82,013		6,923,536		7,025,500
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		77		11,605		636,877		648,559
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises	—		558,026		192,614		61,383		812,023

Corporate debt securities and other debt securities	—		8,766		—		—		8,766
Total fair value	$	24,819	$	1,021,472	$	356,431	$	8,329,896	$	9,732,618

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, 2023 and 2022 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)	2023		2022
Gross realized gains on sales	$	1,030	$	—
Gross realized losses on sales	—		—
Investment securities gains (losses), net	$	1,030	$	—