
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
AFS investment securities:
December 31, 2022
U.S. Treasury	$	49,156	$	—	$	(2,139)	$	47,017
Agency	485,331		—		(53,893)		431,438
Corporate	586,652		—		(44,104)		542,548

Collateralized mortgage obligations	829,928		—		(65,699)		764,229
Mortgage-backed securities	953,678		—		(137,897)		815,781
Total AFS investment securities	$	2,904,745	$	—	$	(303,732)	$	2,601,013

December 31, 2021
U.S. Treasury	$	57,708	$	614	$	(456)	$	57,866
Agency	440,183		2,081		(10,129)		432,135
Corporate	451,621		6,096		(3,856)		453,861
Municipal bonds	1,061,985		32,209		(4,281)		1,089,913
Collateralized mortgage obligations	680,686		2,012		(6,055)		676,643
Mortgage-backed securities	1,586,406		3,220		(26,180)		1,563,446
Total AFS investment securities	$	4,278,589	$	46,232	$	(50,957)	$	4,273,864


(Dollars in thousands)	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrecognized Gain		Gross Unrecognized Loss		Estimated Fair Value
HTM investment securities:
December 31, 2022
Municipal bonds	$	1,148,055	$	(43)	$	1,148,012	$	44	$	(257,430)	$	890,626
Mortgage-backed securities	231,692		—		231,692		—		(33,621)		198,071
Other	8,399		—		8,399		—		—		8,399
Total HTM investment securities	$	1,388,146	$	(43)	$	1,388,103	$	44	$	(291,051)	$	1,097,096

December 31, 2021
Municipal bonds	$	368,344	$	(22)	$	368,322	$	3,834	$	(1,649)	$	370,507
Mortgage-backed securities	11,843		—		11,843		564		—		12,407
Other	1,509		—		1,509		—		—		1,509
Total HTM investment securities	$	381,696	$	(22)	$	381,674	$	4,398	$	(1,649)	$	384,423

The Company reassesses classification of certain investments as part of the ongoing review of the investment securities portfolio. During 2022, the Company transferred all of the AFS municipal bond portfolio of $831.4 million as well as mortgage-backed securities of $255.0 million to HTM securities. The Company intends and has the ability to hold the securities transferred to maturity. The transfer of these securities was accounted for at fair value on the transfer date. In total, the municipal bonds had a net carrying amount of $780.7 million with a pre-tax unrealized loss of $50.8 million, and the mortgage-backed securities had a net carrying amount of $238.8 million with a pre-tax unrealized loss of $16.2 million, and both realized losses were reflected as discounts on the date of transfer. These discounts are accreted into interest income as yield adjustments over the remaining term of the securities. The amortization of the unrealized losses reported in accumulated other comprehensive income (loss) largely offsets the effect on interest income of the accretion of the discounts. No gains or losses were recorded at the time of transfer.

Unrealized gains and losses on AFS investment securities are recognized in stockholders’ equity as accumulated other comprehensive income or loss. At December 31, 2022, the Company had a net unrealized loss on AFS investment securities of $303.7 million, or $217.4 million net of tax in accumulated other comprehensive loss, compared to a net unrealized loss of $4.7 million, or $3.3 million net of tax in accumulated other comprehensive loss, at December 31, 2021.

For investment securities transferred from AFS to HTM, the unrealized gains and losses at the date of transfer continue to be reported in stockholders’ equity as accumulated other comprehensive income or loss and are amortized over the remaining lives of the securities with an offsetting entry to interest income as an adjustment of yield. At December 31, 2022, the unrealized loss on investment securities transferred from AFS to HTM was $66.9 million, or $47.9 million net of tax.

The table below summarizes the number, fair value, and gross unrealized holding losses of the Company’s AFS investment securities in an unrealized loss position for which an allowance for credit losses has not been recorded as of the dates indicated, aggregated by investment category and length of time in a continuous loss position.


	December 31, 2022
	Less than 12 months					12 months or Longer					Total
(Dollars in thousands)	Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses
AFS investment securities:
U.S. Treasury	5	$	33,982	$	(237)	1	$	13,036	$	(1,902)	6	$	47,018	$	(2,139)
Agency	8	79,895		(1,265)		35	351,543		(52,628)		43	431,438		(53,893)
Corporate	35	327,984		(20,840)		21	214,565		(23,264)		56	542,549		(44,104)

Collateralized mortgage obligations	41	522,955		(33,318)		40	241,229		(32,381)		81	764,184		(65,699)
Mortgage-backed securities	13	91,762		(6,987)		68	724,019		(130,910)		81	815,781		(137,897)
Total AFS investment securities	102	$	1,056,578	$	(62,647)	165	$	1,544,392	$	(241,085)	267	$	2,600,970	$	(303,732)


	December 31, 2021
	Less than 12 months					12 months or Longer					Total
(Dollars in thousands)	Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses
AFS investment securities:
U.S. Treasury	3	$	47,235	$	(456)	—	$	—	$	—	3	$	47,235	$	(456)
Agency	19	278,078		(5,634)		16	119,750		(4,495)		35	397,828		(10,129)
Corporate	17	166,563		(849)		3	57,274		(3,007)		20	223,837		(3,856)
Municipal bonds	36	277,564		(4,079)		2	6,596		(202)		38	284,160		(4,281)
Collateralized mortgage obligations	26	226,763		(3,738)		15	121,185		(2,317)		41	347,948		(6,055)
Mortgage-backed securities	103	1,306,455		(20,417)		15	173,121		(5,763)		118	1,479,576		(26,180)
Total AFS investment securities	204	$	2,302,658	$	(35,173)	51	$	477,926	$	(15,784)	255	$	2,780,584	$	(50,957)

The Company reviews individual securities classified as AFS to determine whether a decline in fair value below the amortized cost basis is deemed credit related or due to other factors such as changes in interest rates and general market conditions. An ACL on AFS investment securities is recorded when the fair value of the investment is below its amortized cost and the decline in fair value has been deemed, through the Company’s qualitative assessment, to be credit related. Non-credit related declines in fair value of AFS investment securities, which may be attributed to changes in interest rates and other market related factors, are not recorded through an ACL. Such declines are recorded as an adjustment to accumulated other comprehensive income (loss), net of tax. In the event the Company is required to sell or has the intent to sell an AFS security that has experienced a decline in fair value below its amortized cost, the Company writes the amortized cost of the security down to fair value in the current period.

The Company determines credit losses on both AFS and HTM investment securities through the use of a discounted cash flow approach using the security’s effective interest rate. The ACL is measured as the amount by which an investment security’s amortized cost exceeds the net present value of expected future cash flows. However, the amount of credit losses for AFS investment securities is limited to the amount of a security’s unrealized loss. The ACL is established through a charge to provision for credit losses in current period earnings.

At December 31, 2022 and December 31, 2021, the Company had an ACL of $43,000 and $22,000, respectively, for HTM investment securities classified as municipal bonds. The following table presents a rollforward by major security type of the ACL on the Company's HTM debt securities as of, and for the periods indicated:

The Company had no ACL for AFS investment securities at December 31, 2022 and 2021. The Company performed a qualitative assessment of these investments as of December 31, 2022 and determined that the increase in unrealized losses during 2022 was the result of general market conditions, including changes in interest rates driven by the Federal Reserve’s policy to fight against inflation, and not related to a deterioration in credit quality. As of December 31, 2022, the Company has not recorded credit losses on certain AFS securities that were in an unrealized loss position due to the high quality of the investments, with investment grade ratings, and many of them are issued by U.S. government agencies. Additionally, the Company continues to receive contractual principal and interest payments in a timely manner. The Company does not intend to sell these securities, and it is more likely than not that the Company will not be required to sell the securities prior to their anticipated recoveries. There was no provision for credit losses recognized for AFS investment securities during the years ended December 31, 2022 and 2021.

At December 31, 2022 and 2021, there were no AFS or HTM securities in nonaccrual status. All securities in the portfolio were current with their contractual principal and interest payments. At December 31, 2022 and 2021, there were no securities purchased with deterioration in credit quality since their origination. At December 31, 2022 and 2021, there were no collateral dependent AFS or HTM securities.


	For the Year Ended December 31,
(Dollars in thousands)	2022		2021		2020
Amortized cost of AFS investment securities sold	$	934,703	$	884,231	$	752,630

Gross realized gains	$	13,645	$	23,185	$	15,682
Gross realized losses	(11,935)		(6,279)		(1,800)
Net realized gains on sales of AFS investment securities	$	1,710	$	16,906	$	13,882


	Due in One Year or Less				Due after One Year through Five Years				Due after Five Years through Ten Years				Due after Ten Years				Total
(Dollars in thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
AFS investment securities:
Treasury	$	9,743	$	9,701	$	24,475	$	24,280	$	14,938	$	13,036	$	—	$	—	$	49,156	$	47,017
Agency	25,575		25,281		326,466		299,758		96,148		78,702		37,142		27,697		485,331		431,438
Corporate	—		—		283,332		273,415		303,320		269,133		—		—		586,652		542,548

Collateralized mortgage obligations	34,473		34,192		66,535		64,986		202,571		180,391		526,349		484,660		829,928		764,229
Mortgage-backed securities	—		—		34,922		34,258		519,895		454,049		398,861		327,474		953,678		815,781
Total AFS investment securities	69,791		69,174		735,730		696,697		1,136,872		995,311		962,352		839,831		2,904,745		2,601,013
HTM investment securities:
Municipal bonds	—		—		10,537		9,893		50,674		43,861		1,086,844		836,872		1,148,055		890,626
Mortgage-backed securities	—		—		—		—		—		—		231,692		198,071		231,692		198,071
Other	—		—		—		—		—		—		8,399		8,399		8,399		8,399
Total HTM investment securities	—		—		10,537		9,893		50,674		43,861		1,326,935		1,043,342		1,388,146		1,097,096
Total investment securities	$	69,791	$	69,174	$	746,267	$	706,590	$	1,187,546	$	1,039,172	$	2,289,287	$	1,883,173	$	4,292,891	$	3,698,109

The Company’s equity securities primarily consist of FHLB and FRB stock, which are considered restricted securities and held as a condition of membership of the FHLB and the Board of Governors of the Federal Reserve System. These equity securities without readily determinable fair values are carried at cost less impairment. At December 31, 2022, the Company had $27.7 million in FHLB stock, $74.8 million in FRB stock, and $17.4 million in other stock. At December 31, 2021, the Company had $17.3 million in FHLB stock, $74.5 million in FRB stock, and $25.7 million in other stock.