Investment Securities (Tables)

6 Months Ended

Jun. 30, 2022

Investment Securities

Schedule of amortized cost and fair value of investment securities held to maturity

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
(Dollars in thousands)	Cost		Gains		Losses		Value
June 30, 2022:
U.S. Government agencies	$	197,260	$	—	$	(19,001)	$	178,259
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,685,694		—		(191,302)		1,494,392
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		494,330		—		(41,685)		452,645
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		369,975		—		(53,121)		316,854
Small Business Administration loan-backed securities		59,206		—		(8,670)		50,536
	$	2,806,465	$	—	$	(313,779)	$	2,492,686
December 31, 2021:
U.S. Government agencies	$	112,913	$	—	$	(2,627)	$	110,286
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,120,104		14		(24,278)		1,095,840
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		174,178		—		(4,937)		169,241
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		350,116		304		(8,021)		342,399
Small Business Administration loan-backed securities		62,590		—		(2,292)		60,298
	$	1,819,901	$	318	$	(42,155)	$	1,778,064

Schedule of amortized cost and fair value of investment securities available for sale

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
(Dollars in thousands)	Cost		Gains		Losses		Value
June 30, 2022:
U.S. Treasuries	$	320,391	$	357	$	(4,290)	$	316,458
U.S. Government agencies		220,916		—		(17,829)		203,087
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		2,080,637		2		(220,630)		1,860,009
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		732,616		2		(65,104)		667,514
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,207,129		2,586		(143,893)		1,065,822
State and municipal obligations		1,239,072		622		(171,136)		1,068,558
Small Business Administration loan-backed securities		485,755		813		(31,616)		454,952
Corporate securities		30,607		11		(1,010)		29,608
	$	6,317,123	$	4,393	$	(655,508)	$	5,666,008
December 31, 2021:
U.S. Government agencies	$	98,882	$	—	$	(1,765)	$	97,117
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,851,700		5,324		(25,985)		1,831,039
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		730,949		5,957		(10,911)		725,995
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,220,233		5,438		(18,430)		1,207,241
State and municipal obligations		798,211		16,697		(2,219)		812,689
Small Business Administration loan-backed securities		502,812		2,330		(4,479)		500,663
Corporate securities		18,509		234		(9)		18,734
	$	5,221,296	$	35,980	$	(63,798)	$	5,193,478

Schedule of amortized cost and carrying value of other investment securities

	Carrying
(Dollars in thousands)	Value
June 30, 2022:
Federal Home Loan Bank stock	$	15,095
Federal Reserve Bank stock		150,261
Investment in unconsolidated subsidiaries		3,563
Other nonmarketable investment securities		10,896
	$	179,815
December 31, 2021:
Federal Home Loan Bank stock	$	16,283
Federal Reserve Bank stock		129,716
Investment in unconsolidated subsidiaries		3,563
Other nonmarketable investment securities		11,006
	$	160,568

Schedule of amortized cost and fair value of debt and equity securities by contractual maturity

	Securities				Securities
	Held to Maturity				Available for Sale
	Amortized		Fair		Amortized		Fair
(Dollars in thousands)	Cost		Value		Cost		Value
Due in one year or less	$	—	$	—	$	58,779	$	58,123
Due after one year through five years		64,365		63,287		539,288		529,936
Due after five years through ten years		414,499		388,263		1,110,003		1,008,452
Due after ten years		2,327,601		2,041,136		4,609,053		4,069,497
	$	2,806,465	$	2,492,686	$	6,317,123	$	5,666,008

Schedule of securities with gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position

	Less Than				Twelve Months
	Twelve Months				or More
	Gross Unrealized		Fair		Gross Unrealized		Fair
(Dollars in thousands)	Losses		Value		Losses		Value
June 30, 2022:
Securities Held to Maturity
U.S. Government agencies	$	11,007	$	136,264	$	7,994	$	41,995
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		108,991		982,694		82,311		511,698
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		31,871		401,276		9,814		51,369
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		29,665		172,523		23,456		144,331
Small Business Administration loan-backed securities		—		—		8,670		50,536
	$	181,534	$	1,692,757	$	132,245	$	799,929
Securities Available for Sale
U.S. Treasuries	$	4,290	$	266,868	$	—	$	—
U.S. Government agencies		13,255		182,661		4,574		20,426
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		156,740		1,495,239		63,890		364,307
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		48,241		583,880		16,863		82,614
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		118,072		884,401		25,821		134,664
State and municipal obligations		162,460		978,854		8,676		31,063
Small Business Administration loan-backed securities		21,967		208,617		9,649		123,954
Corporate securities		1,010		24,099		—		—
	$	526,035	$	4,624,619	$	129,473	$	757,028
December 31, 2021:
Securities Held to Maturity
U.S. Government agencies	$	1,745	$	86,168	$	882	$	24,118
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		18,768		868,327		5,510		184,819
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		4,937		169,240		—		—
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		4,902		154,963		3,119		75,450
Small Business Administration loan-backed securities		1,281		37,408		1,011		22,890
	$	31,633	$	1,316,106	$	10,522	$	307,277
Securities Available for Sale
U.S. Government agencies	$	529	$	73,353	$	1,236	$	23,763
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		17,381		1,274,934		8,604		221,435
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		10,911		432,300		—		—
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		13,120		846,581		5,310		98,106
State and municipal obligations		1,867		123,987		352		8,579
Small Business Administration loan-backed securities		2,720		179,168		1,759		110,309
Corporate securities		9		4,991		—		—
	$	46,537	$	2,935,314	$	17,261	$	462,192

Schedule of trading securities

	June 30,		December 31,
(Dollars in thousands)	2022		2021
U.S. Government agencies	$	13,428	$	5,154
Residential mortgage pass-through securities issued or guaranteed by U.S.
government agencies or sponsored enterprises		28,079		6,853
Other residential mortgage issued or guaranteed by U.S. government
agencies or sponsored enterprises		2,236		12,315
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		18,570		29,667
State and municipal obligations		9,357		20,798
Other debt securities		16,418		2,902
	$	88,088	$	77,689

Summary of net (losses) gains on trading securities

	Three Months Ended June 30,				Six Months Ended June 30,
(Dollars in thousands)	2022		2021		2022		2021
Net (losses) gains on sales transaction	$	(380)	$	336	$	(1,620)	$	456
Net mark to mark (losses) gains		(458)		268		(2,434)		(189)
Net (losses) gains on trading securities	$	(838)	$	604	$	(4,054)	$	267