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INVESTMENT SECURITIES - Unrealized Gain/Loss on Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
AFS
Amortized cost	$ 1,282,197	$ 1,366,629
Gross unrealized gains	366	834
Gross unrealized losses	(121,555)	(116,264)
Fair value	1,161,008	1,251,199
Residential mortgage-backed securities
AFS
Amortized cost	189,366	194,141
Gross unrealized gains	106	117
Gross unrealized losses	(10,881)	(10,460)
Fair value	178,591	183,798
Commercial mortgage-backed securities
AFS
Amortized cost	55,083	55,235
Gross unrealized gains	0	0
Gross unrealized losses	(7,613)	(7,479)
Fair value	47,470	47,756
Residential collateralized mortgage obligations
AFS
Amortized cost	407,152	473,269
Gross unrealized gains	24	8
Gross unrealized losses	(35,516)	(33,539)
Fair value	371,660	439,738
Commercial collateralized mortgage obligations
AFS
Amortized cost	62,702	63,456
Gross unrealized gains	0	0
Gross unrealized losses	(6,000)	(6,059)
Fair value	56,702	57,397
Municipal bonds
AFS
Amortized cost	449,327	452,057
Gross unrealized gains	231	670
Gross unrealized losses	(51,458)	(47,853)
Fair value	398,100	404,874
HTM
Amortized cost	2,354	2,371
Gross unrealized gains	0	0
Gross unrealized losses	(49)	(40)
Fair value	2,305	2,331
Corporate debt securities
AFS
Amortized cost	41,159	45,611
Gross unrealized gains	5	34
Gross unrealized losses	(6,012)	(7,098)
Fair value	35,152	38,547
U.S. Treasury securities
AFS
Amortized cost	22,571	22,658
Gross unrealized gains	0	0
Gross unrealized losses	(2,675)	(2,474)
Fair value	19,896	20,184
Agency debentures
AFS
Amortized cost	54,837	60,202
Gross unrealized gains	0	5
Gross unrealized losses	(1,400)	(1,302)
Fair value	$ 53,437	$ 58,905

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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