
	September 30, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale
U.S. Treasury and federal agencies	$	293,785	$	—	$	(27,935)	$	265,850
State and municipal	425,096		—		(84,784)		340,312
Federal agency collateralized mortgage obligations	23,210		—		(1,897)		21,313
Federal agency mortgage-backed pools	200,728		—		(34,839)		165,889

Corporate notes	81,803		338		(10,337)		71,804
Total available for sale investment securities	$	1,024,622	$	338	$	(159,792)	$	865,168
Held to maturity
U.S. Treasury and federal agencies	$	287,561	$	—	$	(53,553)	$	234,008
State and municipal	1,101,933		15		(243,639)		858,309
Federal agency collateralized mortgage obligations	52,573		—		(9,896)		42,677
Federal agency mortgage-backed pools	328,410		—		(64,353)		264,057
Private labeled mortgage-backed pools	32,992		—		(5,694)		27,298
Corporate notes	163,014		—		(32,518)		130,496
Total held to maturity investment securities	$	1,966,483	$	15	$	(409,653)	$	1,556,845


	December 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale
U.S. Treasury and federal agencies	$	294,329	$	—	$	(27,150)	$	267,179
State and municipal	505,006		140		(71,602)		433,544
Federal agency collateralized mortgage obligations	33,011		—		(1,796)		31,215
Federal agency mortgage-backed pools	220,963		—		(30,307)		190,656

Corporate notes	84,393		195		(9,624)		74,964
Total available for sale investment securities	$	1,137,702	$	335	$	(140,479)	$	997,558
Held to maturity
U.S. Treasury and federal agencies	$	295,250	$	—	$	(49,237)	$	246,013
State and municipal	1,127,669		374		(192,458)		935,585
Federal agency collateralized mortgage obligations	56,564		—		(8,865)		47,699
Federal agency mortgage-backed pools	343,953		—		(56,714)		287,239
Private labeled mortgage-backed pools	35,466		—		(5,493)		29,973
Corporate notes	163,846		—		(29,046)		134,800
Total held to maturity investment securities	$	2,022,748	$	374	$	(341,813)	$	1,681,309

The Company elected to transfer 793 AFS securities with an aggregate fair value of $120.9 million to a classification of HTM on March 31, 2022. In accordance with FASB ASC 320–10–55–24, the transfer from AFS to HTM must be recorded at the fair value of the AFS securities at the time of transfer. The net unrealized holding loss of $814,000, net of tax, at the date of transfer was retained in accumulated other comprehensive income (loss), with the associated pre–tax amount retained in the carrying value of the HTM securities. Such amounts will be accreted to comprehensive income over the remaining life of the securities. The fair value of the transferred AFS securities became the book value of the HTM securities at March 31, 2022.

The amortized cost and fair value of securities available for sale and held to maturity at September 30, 2023 and December 31, 2022, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.


	September 30, 2023
	Amortized Cost		Fair Value
Available for sale
Within one year	$	5,449	$	5,329
One to five years	364,641		330,882
Five to ten years	192,161		153,784
After ten years	238,433		187,971
	800,684		677,966
Federal agency collateralized mortgage obligations	23,210		21,313
Federal agency mortgage–backed pools	200,728		165,889

Total available for sale investment securities	$	1,024,622	$	865,168
Held to maturity
Within one year	$	35,434	$	35,149
One to five years	228,119		212,226
Five to ten years	340,018		278,547
After ten years	948,937		696,891
	1,552,508		1,222,813
Federal agency collateralized mortgage obligations	52,573		42,677
Federal agency mortgage–backed pools	328,410		264,057
Private labeled mortgage–backed pools	32,992		27,298
Total held to maturity investment securities	$	1,966,483	$	1,556,845

The following table shows the gross unrealized losses and the fair value of the Company’s investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position.


	September 30, 2023
	Less than 12 Months				12 Months or More				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment Securities
U.S. Treasury and federal agencies	$	1,322	$	(12)	$	498,536	$	(81,476)	$	499,858	$	(81,488)
State and municipal	123,235		(7,558)		1,066,492		(320,865)		1,189,727		(328,423)
Federal agency collateralized mortgage obligations	—		—		63,990		(11,793)		63,990		(11,793)
Federal agency mortgage–backed pools	13		(1)		429,933		(99,191)		429,946		(99,192)
Private labeled mortgage–backed pools	—		—		27,298		(5,694)		27,298		(5,694)
Corporate notes	—		—		200,899		(42,855)		200,899		(42,855)
Total temporarily impaired securities	$	124,570	$	(7,571)	$	2,287,148	$	(561,874)	$	2,411,718	$	(569,445)


	December 31, 2022
	Less than 12 Months				12 Months or More				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment Securities
U.S. Treasury and federal agencies	$	217,357	$	(16,692)	$	295,585	$	(59,695)	$	512,942	$	(76,387)
State and municipal	533,871		(45,881)		757,061		(218,179)		1,290,932		(264,060)
Federal agency collateralized mortgage obligations	40,301		(2,881)		38,613		(7,780)		78,914		(10,661)
Federal agency mortgage–backed pools	49,633		(3,211)		428,243		(83,810)		477,876		(87,021)
Private labeled mortgage–backed pools	—		—		29,973		(5,493)		29,973		(5,493)
Corporate notes	38,906		(6,787)		169,921		(31,883)		208,827		(38,670)
Total temporarily impaired securities	$	880,068	$	(75,452)	$	1,719,396	$	(406,840)	$	2,599,464	$	(482,292)

Certain investments in debt securities are reported in the consolidated financial statements at an amount less than their historical cost. As of September 30, 2023 and December 31, 2022, the Company had 2,651 and 2,828 securities, respectively, with market values below their cost basis. The total fair value of these investments at September 30, 2023 and December 31, 2022 was $2.4 billion and $2.6 billion, which is approximately 99.6% and 97.0%, respectively, of the Company's available for sale and held to maturity securities portfolio. These declines resulted primarily from fluctuations in market interest rates after purchase. Management believes the declines in fair value for these securities are temporary.

No allowance for credit losses for available for sale debt securities or held to maturity securities was recorded at September 30, 2023 or December 31, 2022. Accrued interest receivable on available for sale debt securities and held to maturity securities totaled $16.7 million at September 30, 2023 and $17.8 million at December 31, 2022 and is excluded from the estimate of credit losses.

The U.S. government sponsored entities and agencies and mortgage–backed securities are either explicitly or implicitly guaranteed by the U.S. government, are highly rated by major credit rating agencies, and have a long history of no credit losses. Therefore, for those securities, we do not record expected credit losses.

Based on an evaluation of available evidence, management believes the unrealized losses on state and municipal securities, private labeled mortgage–backed pools and corporate notes were due to changes in interest rates. Due to the contractual terms, the issuers of state and municipal securities are not allowed to settle for less than the amortized cost of the security. In addition, the Company does not intend to sell these securities prior to the recovery of the amortized cost, which may not occur until maturity.


	Three Months Ended				Nine Months Ended
	September 30				September 30
	2023		2022		2023		2022
Sales of securities available for sale
Proceeds	$	—	$	—	$	88,194	$	—
Gross gains	—		—		215		—
Gross losses	—		—		(695)		—