INVESTMENTS (Tables)

6 Months Ended

Jun. 30, 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 June 30, 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	$	36,723	$	0	$	(3,343)	$	33,380
Securities of U.S. government agencies and corporations	0		0		0		0		79,684		0		(9,576)		70,108
Mortgage-backed securities - residential	0		0		0		0		697,784		5		(70,037)		627,752
Mortgage-backed securities - commercial	38,327		0		(2,541)		35,786		762,091		3		(31,727)		730,367
Collateralized mortgage obligations	10,178		0		(460)		9,718		556,531		384		(40,072)		516,843
Obligations of state and other political subdivisions	8,302		133		(123)		8,312		1,070,377		2,710		(88,243)		984,844
Asset-backed securities	0		0		0		0		798,356		128		(42,052)		756,432
Other securities	31,250		0		(1,076)		30,174		127,000		168		(3,314)		123,854
Total	$	88,057	$	133	$	(4,200)	$	83,990	$	4,128,546	$	3,398	$	(288,364)	$	3,843,580

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 June 30, 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
By Contractual Maturity:
Due in one year or less	$	0	$	0	$	6,850	$	6,839
Due after one year through five years	1,080		1,082		105,078		103,623
Due after five years through ten years	36,316		35,350		359,473		336,171
Due after ten years	2,156		2,054		842,383		765,553
Mortgage-backed securities - residential	0		0		697,784		627,752
Mortgage-backed securities - commercial	38,327		35,786		762,091		730,367
Collateralized mortgage obligations	10,178		9,718		556,531		516,843
Asset-backed securities	0		0		798,356		756,432
Total	$	88,057	$	83,990	$	4,128,546	$	3,843,580

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 ACL has not been recorded, aggregated by investment category and the length of time the individual securities have been in a continuous loss position:

	June 30, 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	$	33,380	$	(3,343)	$	0	$	0	$	33,380	$	(3,343)
Securities of U.S. Government agencies and corporations	70,108		(9,576)		0		0		70,108		(9,576)
Mortgage-backed securities - residential	400,570		(37,708)		224,382		(32,329)		624,952		(70,037)
Mortgage-backed securities - commercial	737,115		(30,907)		27,765		(3,361)		764,880		(34,268)
Collateralized mortgage obligations	429,951		(29,304)		73,602		(11,228)		503,553		(40,532)
Obligations of state and other political subdivisions	626,316		(67,853)		126,912		(20,513)		753,228		(88,366)
Asset-backed securities	714,112		(39,664)		25,917		(2,388)		740,029		(42,052)
Other securities	116,117		(3,883)		11,744		(507)		127,861		(4,390)
Total	$	3,127,669	$	(222,238)	$	490,322	$	(70,326)	$	3,617,991	$	(292,564)

	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)