Securities (Tables)

3 Months Ended

Mar. 31, 2023

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
March 31, 2023:
U.S. Government agencies	$	197,264	$	—	$	(28,175)	$	169,089
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,553,373		—		(238,470)		1,314,903
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		468,794		—		(63,317)		405,477
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		360,962		—		(68,141)		292,821
Small Business Administration loan-backed securities		56,280		—		(10,958)		45,322
	$	2,636,673	$	—	$	(409,061)	$	2,227,612
December 31, 2022:
U.S. Government agencies	$	197,262	$	—	$	(29,787)	$	167,475
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,591,646		—		(255,093)		1,336,553
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		474,660		—		(69,664)		404,996
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		362,586		—		(66,304)		296,282
Small Business Administration loan-backed securities		57,087		—		(12,225)		44,862
	$	2,683,241	$	—	$	(433,073)	$	2,250,168

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
March 31, 2023:
U.S. Treasuries	$	273,035	$	—	$	(4,939)	$	268,096
U.S. Government agencies		246,001		—		(25,742)		220,259
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,951,725		—		(278,563)		1,673,162
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		689,575		—		(98,163)		591,412
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,180,323		8		(192,894)		987,437
State and municipal obligations		1,138,809		4		(171,856)		966,957
Small Business Administration loan-backed securities		466,462		194		(41,164)		425,492
Corporate securities		30,571		—		(3,387)		27,184
	$	5,976,501	$	206	$	(816,708)	$	5,159,999
December 31, 2022:
U.S. Treasuries	$	272,416	$	—	$	(6,778)	$	265,638
U.S. Government agencies		245,972		—		(26,884)		219,088
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,996,405		—		(298,052)		1,698,353
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		708,337		—		(107,292)		601,045
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,196,700		2,542		(198,844)		1,000,398
State and municipal obligations		1,269,525		1,210		(205,883)		1,064,852
Small Business Administration loan-backed securities		491,203		302		(46,695)		444,810
Corporate securities		35,583		—		(2,945)		32,638
	$	6,216,141	$	4,054	$	(893,373)	$	5,326,822

Schedule of amortized cost and carrying value of other investment securities

	Carrying
(Dollars in thousands)	Value
March 31, 2023:
Federal Home Loan Bank stock	$	53,335
Federal Reserve Bank stock		150,261
Investment in unconsolidated subsidiaries		3,563
Other nonmarketable investment securities		10,832
	$	217,991
December 31, 2022:
Federal Home Loan Bank stock	$	15,085
Federal Reserve Bank stock		150,261
Investment in unconsolidated subsidiaries		3,563
Other nonmarketable investment securities		10,808
	$	179,717

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	$	—	$	—	$	254,326	$	250,191
Due after one year through five years		101,073		94,058		309,053		295,225
Due after five years through ten years		382,261		337,412		1,148,155		1,001,653
Due after ten years		2,153,339		1,796,142		4,264,967		3,612,930
	$	2,636,673	$	2,227,612	$	5,976,501	$	5,159,999

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
March 31, 2023:
Securities Held to Maturity
U.S. Government agencies	$	—	$	—	$	28,175	$	169,089
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		—		—		238,470		1,314,903
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		1,187		45,925		62,130		359,552
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		13,414		57,771		54,727		235,050
Small Business Administration loan-backed securities		—		—		10,958		45,322
	$	14,601	$	103,696	$	394,460	$	2,123,916
Securities Available for Sale
U.S. Treasuries	$	—	$	—	$	4,939	$	268,096
U.S. Government agencies		1,065		53,935		24,677		166,324
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,027		32,334		277,536		1,640,828
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		2,650		73,464		95,513		517,948
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		10,606		107,009		182,288		874,332
State and municipal obligations		4,250		74,784		167,606		888,984
Small Business Administration loan-backed securities		428		80,092		40,736		278,346
Corporate securities		635		5,863		2,752		21,321
	$	20,661	$	427,481	$	796,047	$	4,656,179
December 31, 2022:
Securities Held to Maturity
U.S. Government agencies	$	5,514	$	78,833	$	24,273	$	88,642
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		65,181		513,086		189,912		823,467
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		30,284		277,868		39,380		127,128
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		14,318		82,895		51,986		213,387
Small Business Administration loan-backed securities		—		—		12,225		44,862
	$	115,297	$	952,682	$	317,776	$	1,297,486
Securities Available for Sale
U.S. Treasuries	$	6,778	$	265,638	$	—	$	—
U.S. Government agencies		8,193		138,807		18,691		80,281
Residential mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		42,767		459,773		255,285		1,238,580
Residential collateralized mortgage-obligations issued by U.S. government
agencies or sponsored enterprises		21,450		274,082		85,842		326,963
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		17,156		206,228		181,688		767,002
State and municipal obligations		97,084		616,631		108,799		391,848
Small Business Administration loan-backed securities		2,152		92,535		44,543		264,933
Corporate securities		2,209		28,374		736		4,264
	$	197,789	$	2,082,068	$	695,584	$	3,073,871

Schedule of trading securities

	March 31,		December 31,
(Dollars in thousands)	2023		2022
U.S. Government agencies	$	3,925	$	11,190
Residential mortgage pass-through securities issued or guaranteed by U.S.
government agencies or sponsored enterprises		3,439		—
Commercial mortgage-backed securities issued by U.S. government
agencies or sponsored enterprises		1,304		4,589
State and municipal obligations		7,122		13,993
Other debt securities		249		1,491
	$	16,039	$	31,263

Summary of net (losses) gains on trading securities

	Three Months Ended March 31,
(Dollars in thousands)	2023		2022
Net losses on sales transaction	$	(139)	$	(1,239)
Net mark to mark losses		(6)		(1,976)
Net losses on trading securities	$	(145)	$	(3,215)