INVESTMENTS (Tables)

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Summary of Held-To-Maturity and Available-For-Sale Investment Securities

The following is a summary of HTM and AFS investment securities as of December 31, 2022:

	Held-to-maturity								Available-for-sale
(Dollars in thousands)	Amortized cost		Unrecognized gain		Unrecognized loss		Fair value		Amortized cost		Unrealized gain		Unrealized loss		Fair value
U.S. Treasuries	$	0	$	0	$	0	$	0	$	37,312	$	0	$	(4,616)	$	32,696
Securities of U.S. government agencies and corporations	0		0		0		0		80,382		0		(13,914)		66,468
Mortgage-backed securities - residential	0		0		0		0		747,478		47		(97,462)		650,063
Mortgage-backed securities - commercial	35,363		0		(4,114)		31,249		676,934		2		(47,374)		629,562
Collateralized mortgage obligations	9,280		0		(827)		8,453		538,970		181		(61,439)		477,712
Obligations of state and other political subdivisions	8,128		105		(201)		8,032		832,066		565		(124,168)		708,463
Asset-backed securities	0		0		0		0		772,261		39		(60,975)		711,325
Other securities	31,250		0		(2,499)		28,751		142,015		0		(8,656)		133,359
Total	$	84,021	$	105	$	(7,641)	$	76,485	$	3,827,418	$	834	$	(418,604)	$	3,409,648

The following is a summary of HTM and AFS investment securities as of December 31, 2021:

	Held-to-maturity								Available-for-sale
(Dollars in thousands)	Amortized cost		Unrecognized gain		Unrecognized loss		Fair value		Amortized cost		Unrealized gain		Unrealized loss		Fair value
U.S. Treasuries	$	0	$	0	$	0	$	0	$	34,961	$	4	$	(189)	$	34,776
Securities of U.S. government agencies and corporations	0		0		0		0		78,998		248		(129)		79,117
Mortgage-backed securities - residential	0		0		0		0		728,050		6,635		(10,548)		724,137
Mortgage-backed securities - commercial	46,362		651		0		47,013		729,948		4,294		(2,352)		731,890
Collateralized mortgage obligations	11,882		221		0		12,103		696,258		7,979		(6,497)		697,740
Obligations of state and other political subdivisions	8,926		915		0		9,841		1,058,735		35,591		(8,594)		1,085,732
Asset-backed securities	0		0		0		0		720,638		1,521		(2,578)		719,581
Other securities	31,250		176		(485)		30,941		133,001		2,114		(242)		134,873
Total	$	98,420	$	1,963	$	(485)	$	99,898	$	4,180,589	$	58,386	$	(31,129)	$	4,207,846

Summary of Investment Securities by Estimated Maturity

The following table provides a summary of investment securities by contractual maturity as of December 31, 2022, except for residential and commercial mortgage-backed securities, collateralized mortgage obligations and asset-backed securities, which are shown as single totals, due to the unpredictability of the timing in principal repayments:

	Held-to-maturity				Available-for-sale
(Dollars in thousands)	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	0	$	0	$	8,230	$	8,125
Due after one year through five years	2,584		2,662		93,629		89,551
Due after five years through ten years	34,920		32,410		292,581		255,143
Due after ten years	1,874		1,711		697,335		588,167
Mortgage-backed securities - residential	0		0		747,478		650,063
Mortgage-backed securities - commercial	35,363		31,249		676,934		629,562
Collateralized mortgage obligations	9,280		8,453		538,970		477,712
Asset-backed securities	0		0		772,261		711,325
Total	$	84,021	$	76,485	$	3,827,418	$	3,409,648

Age of Gross Unrealized Losses and Associated Fair Value by Investment Category

The following tables provide the fair value and gross unrealized losses on investment securities in an unrealized loss position for which an allowance for credit losses was not recorded, aggregated by investment category and the length of time the individual securities have been in a continuous loss position:

	December 31, 2022
	Less than 12 months				12 months or more				Total
(Dollars in thousands)	Fair value		Unrealized loss		Fair value		Unrealized loss		Fair value		Unrealized loss
U.S. Treasuries	$	2,383	$	(46)	$	30,313	$	(4,570)	$	32,696	$	(4,616)
Securities of U.S. government agencies and corporations	0		0		66,468		(13,914)		66,468		(13,914)
Mortgage-backed securities - residential	195,972		(10,413)		443,415		(87,049)		639,387		(97,462)
Mortgage-backed securities - commercial	457,863		(21,020)		189,123		(30,468)		646,986		(51,488)
Collateralized mortgage obligations	205,456		(13,059)		271,377		(49,207)		476,833		(62,266)
Obligations of state and other political subdivisions	301,073		(31,397)		368,673		(92,972)		669,746		(124,369)
Asset-backed securities	250,946		(9,410)		422,090		(51,565)		673,036		(60,975)
Other securities	125,344		(7,283)		31,629		(3,872)		156,973		(11,155)
Total	$	1,539,037	$	(92,628)	$	1,823,088	$	(333,617)	$	3,362,125	$	(426,245)

	December 31, 2021
	Less than 12 months				12 months or more				Total
(Dollars in thousands)	Fair value		Unrealized loss		Fair value		Unrealized loss		Fair value		Unrealized loss
U.S. Treasuries	$	24,755	$	(190)	$	0	$	0	$	24,755	$	(190)
Securities of U.S. Government agencies and corporations	17,382		(128)		0		0		17,382		(128)
Mortgage-backed securities - residential	459,098		(8,375)		78,090		(2,173)		537,188		(10,548)
Mortgage-backed securities - commercial	205,520		(2,149)		13,818		(203)		219,338		(2,352)
Collateralized mortgage obligations	369,318		(6,110)		12,485		(387)		381,803		(6,497)
Obligations of state and other political subdivisions	380,735		(7,543)		55,568		(1,051)		436,303		(8,594)
Asset-backed securities	482,118		(2,578)		0		0		482,118		(2,578)
Other securities	31,896		(354)		11,877		(373)		43,773		(727)
Total	$	1,970,822	$	(27,427)	$	171,838	$	(4,187)	$	2,142,660	$	(31,614)