INVESTMENT SECURITIES - Securities With Unrealized Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Available-for-sale
Available-for-sale, less than 12 months, estimated fair value	$ 23,309	$ 37,952
Available-for-sale, less than 12 months, gross unrealized losses	(1,060)	(411)
Available-for-sale, 12 months or more, estimated fair value	2,636,931	2,429,271
Available-for-sale, 12 months or more, gross unrealized losses	(381,857)	(323,244)
Available-for-sale, total, estimated fair value	2,660,240	2,467,223
Available-for-sale, total, gross unrealized losses	(382,917)	(323,655)
U.S. Treasury
Available-for-sale
Available-for-sale, less than 12 months, estimated fair value		0
Available-for-sale, less than 12 months, gross unrealized losses		0
Available-for-sale, 12 months or more, estimated fair value		996
Available-for-sale, 12 months or more, gross unrealized losses		(3)
Available-for-sale, total, estimated fair value		996
Available-for-sale, total, gross unrealized losses		(3)
U.S. Government agencies
Available-for-sale
Available-for-sale, less than 12 months, estimated fair value	2,247	717
Available-for-sale, less than 12 months, gross unrealized losses	(17)	(7)
Available-for-sale, 12 months or more, estimated fair value	43,767	51,186
Available-for-sale, 12 months or more, gross unrealized losses	(603)	(1,040)
Available-for-sale, total, estimated fair value	46,014	51,903
Available-for-sale, total, gross unrealized losses	(620)	(1,047)
Mortgage-backed securities
Available-for-sale
Available-for-sale, less than 12 months, estimated fair value	15,305	7,480
Available-for-sale, less than 12 months, gross unrealized losses	(74)	(189)
Available-for-sale, 12 months or more, estimated fair value	1,672,723	1,384,532
Available-for-sale, 12 months or more, gross unrealized losses	(189,686)	(152,595)
Available-for-sale, total, estimated fair value	1,688,028	1,392,012
Available-for-sale, total, gross unrealized losses	(189,760)	(152,784)
State and political subdivisions
Available-for-sale
Available-for-sale, less than 12 months, estimated fair value	5,757	16,843
Available-for-sale, less than 12 months, gross unrealized losses	(969)	(195)
Available-for-sale, 12 months or more, estimated fair value	824,265	829,754
Available-for-sale, 12 months or more, gross unrealized losses	(186,123)	(157,374)
Available-for-sale, total, estimated fair value	830,022	846,597
Available-for-sale, total, gross unrealized losses	(187,092)	(157,569)
Other securities
Available-for-sale
Available-for-sale, less than 12 months, estimated fair value	0	12,912
Available-for-sale, less than 12 months, gross unrealized losses	0	(20)
Available-for-sale, 12 months or more, estimated fair value	96,176	162,803
Available-for-sale, 12 months or more, gross unrealized losses	(5,445)	(12,232)
Available-for-sale, total, estimated fair value	96,176	175,715
Available-for-sale, total, gross unrealized losses	$ (5,445)	$ (12,252)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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