The following tables set forth the amortized cost, gross unrealized gains and losses, and estimated fair value of debt securities classified as available for sale and held to maturity at December 31, 2023 and 2022. Amortized cost of securities does not include accrued interest which is reflected in the accrued interest line item on the consolidated balance sheets totaling $27.4 million and $29.1 million at December 31, 2023 and December 31, 2022, respectively. During the twelve months ended December 31, 2022, the Company transferred securities with an aggregate fair value of $561.8 million, inclusive of an unrealized loss of $15.4 million, from the available for sale portfolio to the held to maturity portfolio; as such, the securities were recorded with an amortized cost of $561.8 million within the held to maturity portfolio. The unrealized loss is reflected in accumulated other comprehensive income and is being amortized to interest income over the remaining lives of the securities.


Securities Available for Sale
	December 31, 2023								December 31, 2022
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
($ in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	97,741	$	1,581	$	1,514	$	97,808	$	113,211	$	—	$	2,346	$	110,865
Municipal obligations		203,533		79		2,200		201,412		207,014		59		3,981		203,092
Residential mortgage-backed securities		2,440,411		2,734		329,279		2,113,866		2,655,381		224		398,619		2,256,986
Commercial mortgage-backed securities		2,683,872		7,176		253,576		2,437,472		3,234,278		2,032		342,880		2,893,430
Collateralized mortgage obligations		47,661		—		3,376		44,285		76,830		—		6,242		70,588
Corporate debt securities		23,500		—		3,148		20,352		23,500		—		2,420		21,080
Total	$	5,496,718	$	11,570	$	593,093	$	4,915,195	$	6,310,214	$	2,315	$	756,488	$	5,556,041


Securities Held to Maturity
	December 31, 2023								December 31, 2022
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
($ in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	413,490	$	179	$	43,971	$	369,698	$	426,454	$	21	$	49,044	$	377,431
Municipal obligations		664,488		1,252		19,593		646,147		698,908		753		26,558		673,103
Residential mortgage-backed securities		654,262		—		59,223		595,039		734,478		—		72,532		661,946
Commercial mortgage-backed securities		920,048		—		75,803		844,245		948,691		—		87,211		861,480
Collateralized mortgage obligations		32,491		—		1,702		30,789		43,964		—		2,526		41,438
Total	$	2,684,779	$	1,431	$	200,292	$	2,485,918	$	2,852,495	$	774	$	237,871	$	2,615,398

The Company held no securities classified as trading at December 31, 2023 or 2022.

The following tables present the amortized cost and fair value of debt securities at December 31, 2023 by contractual maturity. Actual maturities will differ from contractual maturities because of rights to call or repay obligations with or without penalties and scheduled and unscheduled principal payments on mortgage-backed securities and collateral mortgage obligations.

Securities with carrying values totaling approximately $4.7 billion at December 31, 2023 and $4.9 billion at December 31, 2022 were pledged as collateral, primarily to secure public deposits or securities sold under agreements to repurchase.

The Company’s policy is to invest only in securities of investment grade quality. These investments are largely limited to U.S. agency securities and municipal securities. Management has concluded, based on the long history of no credit losses, that the expectation of nonpayment of the held to maturity securities carried at amortized cost is zero for securities that are backed by the full faith and credit of and/or guaranteed by the U.S. government. As such, no allowance for credit losses has been recorded for these securities. The municipal portfolio is analyzed separately for allowance for credit loss in accordance with the applicable guidance for each portfolio as noted below.

The Company evaluates credit impairment for individual securities available for sale whose fair value was below amortized cost with a more than inconsequential risk of default and where the Company had assessed whether the decline in fair value was significant enough to suggest a credit event occurred. There were no securities with a material credit loss event and therefore, no allowance for credit loss was recorded in any period presented.

The fair value and gross unrealized losses for securities classified as available for sale with unrealized losses at December 31, 2023 are presented in the table below.


Available for sale
	December 31, 2023
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	7,790	$	1,514	$	7,790	$	1,514
Municipal obligations		49,832		374		128,965		1,826		178,797		2,200
Residential mortgage-backed securities		3,062		25		1,795,154		329,254		1,798,216		329,279
Commercial mortgage-backed securities		—		—		2,227,703		253,576		2,227,703		253,576
Collateralized mortgage obligations		—		—		44,285		3,376		44,285		3,376
Corporate debt securities		—		—		19,852		3,148		19,852		3,148
Total	$	52,894	$	399	$	4,223,749	$	592,694	$	4,276,643	$	593,093

The fair value and gross unrealized losses for securities classified as available for sale with unrealized losses at December 31, 2022 are presented in the table below.


Available for sale
	December 31, 2022
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	102,607	$	754	$	8,258	$	1,592	$	110,865	$	2,346
Municipal obligations		192,334		3,981		—		—		192,334		3,981
Residential mortgage-backed securities		636,060		49,790		1,611,832		348,829		2,247,892		398,619
Commercial mortgage-backed securities		1,489,974		114,195		1,351,530		228,685		2,841,504		342,880
Collateralized mortgage obligations		41,703		3,275		28,884		2,967		70,587		6,242
Corporate debt securities		13,194		1,306		7,386		1,114		20,580		2,420
Total	$	2,475,872	$	173,301	$	3,007,890	$	583,187	$	5,483,762	$	756,488

At the end of each reporting period, the Company evaluated its held to maturity municipal obligation portfolio for credit loss using probability of default and loss given default models. The models were run using a long-term average probability of default migration and with a probability weighting of Moody’s economic forecasts. The resulting credit loss, if any, were negligible and no allowance for credit losses was recorded.

The fair value and gross unrealized losses for securities classified as held to maturity with unrealized losses at December 31, 2023 are presented in the table below.


Held to maturity
	December 31, 2023
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	9,530	$	63	$	339,533	$	43,908	$	349,063	$	43,971
Municipal obligations		343,401		1,801		226,165		17,792		569,566		19,593
Residential mortgage-backed securities		—		—		595,039		59,223		595,039		59,223
Commercial mortgage-backed securities		—		—		844,245		75,803		844,245		75,803
Collateralized mortgage obligations		—		—		30,789		1,702		30,789		1,702
Total	$	352,931	$	1,864	$	2,035,771	$	198,428	$	2,388,702	$	200,292

The fair value and gross unrealized losses for securities classified as held to maturity with unrealized losses at December 31, 2022 are presented in the table below.


Held to maturity	December 31, 2022
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	145,893	$	13,245	$	226,499	$	35,799	$	372,392	$	49,044
Municipal obligations		560,288		8,878		64,346		17,680		624,634		26,558
Residential mortgage-backed securities		391,146		30,515		270,800		42,017		661,946		72,532
Commercial mortgage-backed securities		697,827		56,899		163,653		30,312		861,480		87,211
Collateralized mortgage obligations		41,438		2,526		—		—		41,438		2,526
Total	$	1,836,592	$	112,063	$	725,298	$	125,808	$	2,561,890	$	237,871

At December 31, 2023 and 2022, the Company had 698 and 757 securities, respectively, with market values below their cost basis. There were no material unrealized losses related to the marketability of the securities or the issuers’ abilities to meet contractual obligations. In all cases, the indicated impairment on these debt securities would be recovered no later than the security’s maturity date or possibly earlier if the market price for the security increases with a reduction in the yield required by the market. The unrealized losses were deemed to be materially non-credit related at December 31, 2023 and 2022. As noted above, no allowance for credit loss was recorded as of December 31, 2023 or 2022. The Company had adequate liquidity and, therefore, neither planned to nor expected to be required to liquidate these securities before recovery of the amortized cost basis.