
	September 30, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Allowance for Credit Losses		Estimated Fair Value
U.S. Treasury notes and bonds	$	61,033	$	—	$	6,033	$	—	$	55,000
Mortgage-backed securities, residential	486,189		—		97,158		—		389,031
Obligations of states and political subdivisions	39,535		—		3,382		—		36,153
Corporate bonds and notes	25,750		—		5,405		—		20,345
SBA loan pools	71,330		96		2,951		—		68,475

Total	$	683,837	$	96	$	114,929	$	—	$	569,004


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury notes and bonds	$	61,800	$	—	$	6,225	$	55,574
Mortgage-backed securities, residential	518,838		—		83,707		435,131

Obligations of states and political subdivisions	39,828		2		938		38,892
Corporate bonds and notes	25,750		—		3,780		21,970
SBA loan pools	82,982		155		2,116		81,022


Total	$	729,198	$	157	$	96,766	$	632,589


	September 30, 2023
	Amortized Cost		Unrecognized Gains		Unrecognized Losses		Allowance for Credit Losses		Estimated Fair Value
Obligations of states and political subdivisions	$	824	$	—	$	—	$	—	$	824
Time deposits with other financial institutions	980		—		25		—		955
Total	$	1,804	$	—	$	25	$	—	$	1,779


	December 31, 2022
	Amortized Cost		Unrecognized Gains		Unrecognized Losses		Estimated Fair Value
Obligations of states and political subdivisions	$	952	$	—	$	—	$	952
Time deposits with other financial institutions	1,472		—		22		1,450
Total	$	2,424	$	—	$	22	$	2,402

The amortized cost and estimated fair value of debt securities are shown below by expected maturity. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately (in thousands):


	September 30, 2023
	Available for Sale				Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Within one year	$	5,480	$	5,243	$	529	$	523
After one, but within five years	101,840		91,028		635		616
After five, but within ten years	18,528		14,821		640		640
After ten years	470		406		—		—
	126,318		111,498		1,804		1,779
Mortgage-backed securities, residential	486,189		389,031		—		—

SBA loan pools	71,330		68,475		—		—
Total	$	683,837	$	569,004	$	1,804	$	1,779

There were no proceeds from sales and calls of securities resulting in gains or losses for the nine month periods ended September 30, 2023 and 2022.

The following tables summarize the investment securities available for sale with unrealized losses at September 30, 2023 and December 31, 2022 by aggregated major security type and length of time in a continuous unrealized loss position (in thousands):


	Less than 12 months				12 months or longer				Total
September 30, 2023	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. Treasury notes and bonds	$	981	$	14	$	54,019	$	6,019	$	55,000	$	6,033
Mortgage-backed securities, residential	—		—		389,031		97,158		389,031		97,158
Obligations of states and political subdivisions	16,794		1,460		19,359		1,922		36,153		3,382
Corporate bonds and notes	7,269		2,732		13,076		2,673		20,345		5,405
SBA loan pools	6,474		15		54,094		2,936		60,568		2,951

Total temporarily impaired securities	$	31,518	$	4,221	$	529,579	$	110,708	$	561,097	$	114,929


	Less than 12 months				12 months or longer				Total
December 31, 2022	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. Treasury notes and bonds	$	1,011	$	30	$	54,563	$	6,195	$	55,574	$	6,225
Mortgage-backed securities, residential	79,891		7,621		355,240		76,086		435,131		83,707
Obligations of states and political subdivisions	37,847		938		—		—		37,847		938
Corporate bonds and notes	4,515		485		7,455		3,295		11,970		3,780
SBA loan pools	14,333		925		51,123		1,191		65,456		2,116
Total temporarily impaired securities	$	137,597	$	9,999	$	468,381	$	86,767	$	605,978	$	96,766

Management assesses the decline in fair value of investment securities on a regular basis. Unrealized losses on debt securities may occur from current market conditions, increases in interest rates since the time of purchase, a structural change in an investment, volatility of earnings of a specific issuer, or deterioration in credit quality of the issuer. Management evaluates both qualitative and quantitative factors to assess whether an impairment exists. The following is a discussion of the credit quality characteristics of portfolio segments carrying material unrealized losses as of September 30, 2023.

At September 30, 2023, the majority of the Corporation’s unrealized losses in available for sale investment securities related to mortgage-backed securities, issued by government-sponsored entities and agencies. Declines in fair value are attributable to changes in interest rates and illiquidity, not credit quality. The Corporation does not have the intent, and it is not likely to be required to, sell these securities prior to their anticipated recovery. Because the Corporation considers these obligations to carry zero loss estimates, no ACL has been recorded as of September 30, 2023.