INVESTMENTS (Tables)

3 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost and Estimated Fair Values of Investments

The amortized cost and estimated fair values of investments available-for-sale and held-to-maturity at the dates indicated are presented in the following table:

	March 31, 2024								December 31, 2023
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale debt securities:
U.S. treasuries and government agencies	$	96,866	$	—	$	(4,630)	$	92,236	$	101,678	$	—	$	(4,751)	$	96,927
State and municipal	310,502		—		(46,516)		263,986		311,505		1		(43,292)		268,214
Mortgage-backed and asset-backed	819,214		83		(74,778)		744,519		807,636		181		(70,277)		737,540
Total available-for-sale debt securities	$	1,226,582	$	83	$	(125,924)	$	1,100,741	$	1,220,819	$	182	$	(118,320)	$	1,102,681
Held-to-maturity debt securities:
Mortgage-backed and asset-backed	231,354		—		(38,556)		192,798		236,165		—		(35,754)		200,411
Total held-to-maturity debt securities	$	231,354	$	—	$	(38,556)	$	192,798	$	236,165	$	—	$	(35,754)	$	200,411
Total debt securities	$	1,457,936	$	83	$	(164,480)	$	1,293,539	$	1,456,984	$	182	$	(154,074)	$	1,303,092

Schedule of Gross Unrealized Losses and Fair Value by Length of Time in Unrealized Loss Position

Gross unrealized losses and fair value by length of time that the individual available-for-sale debt securities have been in an unrealized loss position at the dates indicated are presented in the following table:

	March 31, 2024
	Number of Securities	Less Than 12 Months				12 Months or More				Total
(Dollars in thousands)		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. treasuries and government agencies	9	$	—	$	—	$	92,236	$	4,630	$	92,236	$	4,630
State and municipal	123	3,789		48		258,977		46,468		262,766		46,516
Mortgage-backed and asset-backed	332	55,845		436		664,980		74,342		720,825		74,778
Total	464	$	59,634	$	484	$	1,016,193	$	125,440	$	1,075,827	$	125,924

	December 31, 2023
	Number of Securities	Less Than 12 Months				12 Months or More				Total
(Dollars in thousands)		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. treasuries and government agencies	10	$	—	$	—	$	96,927	$	4,751	$	96,927	$	4,751
State and municipal	123	4,162		84		262,081		43,208		266,243		43,292
Mortgage-backed and asset-backed	321	22,731		106		691,281		70,171		714,012		70,277
Total	454	$	26,893	$	190	$	1,050,289	$	118,130	$	1,077,182	$	118,320

Estimated Fair Values of Debt Securities by Contractual Maturity

The estimated fair values and amortized costs of available-for-sale and held-to-maturity debt securities by contractual maturity are provided in the following tables:

	March 31, 2024				December 31, 2023
(In thousands)	Fair Value		Amortized Cost		Fair Value		Amortized Cost
Available-for-sale debt securities
U.S. treasuries and government agencies:
One year or less	$	12,922	$	12,988	$	17,798	$	17,979
One to five years	79,314		83,878		79,129		83,699
Five to ten years	—		—		—		—
After ten years	—		—		—		—
State and municipal:
One year or less	28,318		28,739		22,345		22,793
One to five years	28,586		29,770		33,282		34,288
Five to ten years	48,992		57,965		46,355		54,487
After ten years	158,090		194,028		166,232		199,937
Mortgage-backed and asset-backed:
One year or less	26,396		26,704		20,814		21,111
One to five years	27,290		28,067		29,823		30,666
Five to ten years	267,178		292,078		256,924		280,209
After ten years	423,655		472,365		429,979		475,650
Total available-for-sale debt securities	$	1,100,741	$	1,226,582	$	1,102,681	$	1,220,819

	March 31, 2024				December 31, 2023
(In thousands)	Fair Value		Amortized Cost		Fair Value		Amortized Cost
Held-to-maturity debt securities
Mortgage-backed and asset-backed:
One year or less	$	—	$	—	$	—	$	—
One to five years	—		—		—		—
Five to ten years	30,070		33,326		31,434		34,458
After ten years	162,728		198,028		168,977		201,707
Total held-to-maturity debt securities	$	192,798	$	231,354	$	200,411	$	236,165

Summary of Other Investments

Other investments are presented in the following table:

(In thousands)	March 31, 2024		December 31, 2023
Federal Reserve Bank stock, at cost	$	39,152	$	39,125
Federal Home Loan Bank of Atlanta stock, at cost	33,566		35,805
Other	677		677
Total other investments, at cost	$	73,395	$	75,607