INVESTMENTS (Tables)

6 Months Ended

Jun. 30, 2023

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:

	June 30, 2023								December 31, 2022
(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	$	101,299	$	—	$	(6,954)	$	94,345	$	100,926	$	—	$	(7,304)	$	93,622
State and municipal	318,815		1		(50,565)		268,251		322,519		4		(56,526)		265,997
Mortgage-backed and asset-backed	868,704		40		(87,652)		781,092		943,398		73		(88,552)		854,919
Total available-for-sale debt securities	$	1,288,818	$	41	$	(145,171)	$	1,143,688	$	1,366,843	$	77	$	(152,382)	$	1,214,538
Held-to-maturity debt securities:
Mortgage-backed and asset-backed	247,814		—		(39,152)		208,662		259,452		—		(39,329)		220,123
Total held-to-maturity debt securities	$	247,814	$	—	$	(39,152)	$	208,662	$	259,452	$	—	$	(39,329)	$	220,123
Total debt securities	$	1,536,632	$	41	$	(184,323)	$	1,352,350	$	1,626,295	$	77	$	(191,711)	$	1,434,661

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 tables:

	June 30, 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	$	—	$	—	$	94,345	$	6,954	$	94,345	$	6,954
State and municipal	127	17,222		488		249,495		50,077		266,717		50,565
Mortgage-backed and asset-backed	327	158,418		6,042		613,216		81,610		771,634		87,652
Total	464	$	175,640	$	6,530	$	957,056	$	138,641	$	1,132,696	$	145,171

	December 31, 2022
	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	$	53,139	$	3,653	$	40,483	$	3,651	$	93,622	$	7,304
State and municipal	130	200,439		30,803		62,482		25,723		262,921		56,526
Mortgage-backed and asset-backed	324	526,387		44,952		297,216		43,600		823,603		88,552
Total	464	$	779,965	$	79,408	$	400,181	$	72,974	$	1,180,146	$	152,382

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.

	June 30, 2023				December 31, 2022
(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	$	14,580	$	14,984	$	—	$	—
One to five years	79,765		86,315		93,622		100,926
Five to ten years	—		—		—		—
After ten years	—		—		—		—
State and municipal:
One year or less	6,799		6,842		8,694		8,783
One to five years	53,557		55,926		51,576		53,948
Five to ten years	36,343		43,156		28,806		34,042
After ten years	171,552		212,891		176,921		225,746
Mortgage-backed and asset-backed:
One year or less	4,692		4,744		7,622		7,704
One to five years	47,004		48,742		45,366		46,802
Five to ten years	274,805		305,295		303,697		335,285
After ten years	454,591		509,923		498,234		553,607
Total available-for-sale debt securities	$	1,143,688	$	1,288,818	$	1,214,538	$	1,366,843

	June 30, 2023				December 31, 2022
(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	32,997		36,828		35,304		39,213
After ten years	175,665		210,986		184,819		220,239
Total held-to-maturity debt securities	$	208,662	$	247,814	$	220,123	$	259,452

Summary of Other Investments

Other investments are presented in the following table:

(In thousands)	June 30, 2023		December 31, 2022
Federal Reserve Bank stock, at cost	$	38,961	$	38,873
Federal Home Loan Bank of Atlanta stock, at cost	32,414		29,668
Other	677		677
Total other investments, at cost	$	72,052	$	69,218