Securities (Tables)

3 Months Ended

Mar. 31, 2024

Securities

Schedule of amortized cost and estimated fair value of securities

			Gross		Gross		Allowance		Estimated
	Amortized		Unrealized		Unrealized		for Credit		Fair
March 31, 2024	Cost		Gains		(Losses)		Losses		Value
	(Dollars in thousands)
Securities available-for-sale:
U.S. Treasury	$	352,237	$	—	$	(4,784)	$	—	$	347,453
Agency mortgage-backed securities		61,916		—		(4,895)		—		57,021
Total	$	414,153	$	—	$	(9,679)	$	—	$	404,474
			Gross		Gross		Estimated		Allowance
	Amortized		Unrecognized		Unrecognized		Fair		for Credit
March 31, 2024	Cost		Gains		(Losses)		Value		Losses
	(Dollars in thousands)
Securities held-to-maturity:
Agency mortgage-backed securities	$	604,458	$	83	$	(92,415)	$	512,126	$	—
Municipals - exempt from Federal tax		31,803		1		(1,072)		30,732		(12)
Total	$	636,261	$	84	$	(93,487)	$	542,858	$	(12)

			Gross		Gross		Allowance		Estimated
	Amortized		Unrealized		Unrealized		for Credit		Fair
December 31, 2023	Cost		Gains		(Losses)		Losses		Value
	(Dollars in thousands)
Securities available-for-sale:
U.S. Treasury	$	387,990	$	—	$	(5,621)	$	—	$	382,369
Agency mortgage-backed securities		64,580		—		(4,313)		—		60,267
Total	$	452,570	$	—	$	(9,934)	$	—	$	442,636
			Gross		Gross		Estimated		Allowance
	Amortized		Unrecognized		Unrecognized		Fair		for Credit
December 31, 2023	Cost		Gains		(Losses)		Value		Losses
	(Dollars in thousands)
Securities held-to-maturity:
Agency mortgage-backed securities	$	618,374	$	282	$	(86,011)	$	532,645	$	—
Municipals - exempt from Federal tax		32,203		3		(724)		31,482		(12)
Total	$	650,577	$	285	$	(86,735)	$	564,127	$	(12)

Schedule of securities with unrealized losses

	Less Than 12 Months				12 Months or More				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
March 31, 2024	Value		(Losses)		Value		(Losses)		Value		(Losses)
	(Dollars in thousands)
Securities available-for-sale:
U.S. Treasury	$	4,907	$	(65)	$	342,546	$	(4,719)	$	347,453	$	(4,784)
Agency mortgage-backed securities		—		—		57,021		(4,895)		57,021		(4,895)
Total	$	4,907	$	(65)	$	399,567	$	(9,614)	$	404,474	$	(9,679)
Securities held-to-maturity:
Agency mortgage-backed securities	$	—	$	—	$	500,329	$	(92,415)	$	500,329	$	(92,415)
Municipals — exempt from Federal tax		9,246		(147)		20,226		(925)		29,472		(1,072)
Total	$	9,246	$	(147)	$	520,555	$	(93,340)	$	529,801	$	(93,487)

	Less Than 12 Months				12 Months or More				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
December 31, 2023	Value		(Losses)		Value		(Losses)		Value		(Losses)
	(Dollars in thousands)
Securities available-for-sale:
U.S. Treasury	$	4,926	$	(40)	$	377,443	$	(5,581)	$	382,369	$	(5,621)
Agency mortgage-backed securities		—		—		60,267		(4,313)		60,267		(4,313)
Total	$	4,926	$	(40)	$	437,710	$	(9,894)	$	442,636	$	(9,934)
Securities held-to-maturity:
Agency mortgage-backed securities	$	—	$	—	$	520,615	$	(86,011)	$	520,615	$	(86,011)
Municipals — exempt from Federal tax		9,790		(176)		13,151		(548)		22,941		(724)
Total	$	9,790	$	(176)	$	533,766	$	(86,559)	$	543,556	$	(86,735)

Schedule of amortized cost and estimated fair values of securities, by contractual maturity

	Available-for-sale
	Amortized		Estimated
	Cost		Fair Value
	(Dollars in thousands)
Due three months or less	$	110,872	$	110,511
Due after three months through one year		100,763		99,531
Due after one through five years		140,602		137,411
Agency mortgage-backed securities		61,916		57,021
Total	$	414,153	$	404,474
	Held-to-maturity
	Amortized		Estimated
	Cost (1)		Fair Value
	(Dollars in thousands)
Due after three months through one year	$	665	$	661
Due after one through five years		8,362		8,140
Due after five through ten years		22,776		21,931
Agency mortgage-backed securities		604,458		512,126
Total	$	636,261	$	542,858

(1) Gross of the allowance for credit losses of ($12,000) at March 31, 2024.

Schedule of roll-forward by major security type of the allowance for credit losses on debt securities held-to-maturity

		Municipals
		(Dollars in thousands)
Beginning balance January 1, 2024	$	12
Provision for credit losses		—
Ending balance March 31, 2024	$	12