INVESTMENT SECURITIES - Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2025 USD ($) security	Dec. 31, 2024 USD ($) security
Fair Value
Less than 12 Months	$ 70,221	$ 123,122
12 Months or Longer	1,242,023	1,230,622
Total	1,312,244	1,353,744
Gross Unrealized Losses
Less than 12 Months	1,566	3,775
12 Months or Longer	239,980	235,078
Total	$ 241,546	$ 238,853
Number of Securities | security	747	760
U.S. Government-sponsored agency securities
Fair Value
Less than 12 Months	$ 0	$ 0
12 Months or Longer	79,926	79,381
Total	79,926	79,381
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	13,832	16,081
Total	$ 13,832	$ 16,081
Number of Securities | security	12	12
State and municipal
Fair Value
Less than 12 Months	$ 14,702	$ 40,398
12 Months or Longer	828,805	820,663
Total	843,507	861,061
Gross Unrealized Losses
Less than 12 Months	921	2,115
12 Months or Longer	148,649	131,271
Total	$ 149,570	$ 133,386
Number of Securities | security	611	611
U.S. Government-sponsored mortgage-backed securities
Fair Value
Less than 12 Months	$ 55,519	$ 82,724
12 Months or Longer	320,890	318,310
Total	376,409	401,034
Gross Unrealized Losses
Less than 12 Months	645	1,660
12 Months or Longer	76,969	87,064
Total	$ 77,614	$ 88,724
Number of Securities | security	114	127
Corporate obligations
Fair Value
Less than 12 Months	$ 0	$ 0
12 Months or Longer	12,402	12,268
Total	12,402	12,268
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	530	662
Total	$ 530	$ 662
Number of Securities | security	10	10