INVESTMENT SECURITIES - Summary of Investment Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands	Sep. 30, 2025 USD ($) security	Dec. 31, 2024 USD ($) security
Fair Value
Less than 12 Months	$ 13,985	$ 123,122
12 Months or Longer	1,262,927	1,230,622
Total	1,276,912	1,353,744
Gross Unrealized Losses
Less than 12 Months	342	3,775
12 Months or Longer	197,972	235,078
Total	$ 198,314	$ 238,853
Number of Securities | security	716	760
U.S. Government-sponsored agency securities
Fair Value
Less than 12 Months	$ 0	$ 0
12 Months or Longer	77,897	79,381
Total	77,897	79,381
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	12,407	16,081
Total	$ 12,407	$ 16,081
Number of Securities | security	12	12
State and municipal
Fair Value
Less than 12 Months	$ 8,549	$ 40,398
12 Months or Longer	854,844	820,663
Total	863,393	861,061
Gross Unrealized Losses
Less than 12 Months	118	2,115
12 Months or Longer	116,265	131,271
Total	$ 116,383	$ 133,386
Number of Securities | security	602	611
U.S. Government-sponsored mortgage-backed securities
Fair Value
Less than 12 Months	$ 5,436	$ 82,724
12 Months or Longer	321,624	318,310
Total	327,060	401,034
Gross Unrealized Losses
Less than 12 Months	224	1,660
12 Months or Longer	68,922	87,064
Total	$ 69,146	$ 88,724
Number of Securities | security	95	127
Corporate obligations
Fair Value
Less than 12 Months	$ 0	$ 0
12 Months or Longer	8,562	12,268
Total	8,562	12,268
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	378	662
Total	$ 378	$ 662
Number of Securities | security	7	10