COMMITMENTS AND CONTINGENCIES - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Jun. 30, 2024	Jan. 01, 2024	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Line Items]
Reserves for unfunded commitments	$ 17,100	$ 18,400
Loans and Leases Receivable, Commitments, Fixed Rates	100,100	108,200
Loans and Leases Receivable, Commitments, Variable Rates	$ 4,000,000	$ 4,400,000
Loan Commitments, Fixed Interest Rate Range, Minimum	0.00%	0.00%
Loan Commitments, Fixed Interest Rate Range, Maximum	21.00%	21.00%
Loan Commitments, Fixed Rate, Maturities, Minimum	1 year	1 year
Loan Commitments, Fixed Rate, Maturities, Maximum	31 years	31 years 7 months 6 days
Letters of credit issued to guarantee performance of a client to a third party	$ 60,900	$ 34,900
Derivative, Notional Amount	20,062,151	19,339,867
Stockholders' Equity Attributable to Parent	2,450,438	2,267,974	$ 2,326,439		$ 2,129,509	$ 2,143,419	$ 2,041,373
Estimated Litigation Liability	0	0
Retained earnings
Commitments and Contingencies Disclosure [Line Items]
Stockholders' Equity Attributable to Parent	1,234,375	1,136,718	$ 1,204,844		$ 1,101,905	$ 1,060,715	$ 968,237
Cumulative Effect, Period of Adoption, Adjustment [Member]
Commitments and Contingencies Disclosure [Line Items]
Stockholders' Equity Attributable to Parent		599
Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained earnings
Commitments and Contingencies Disclosure [Line Items]
Stockholders' Equity Attributable to Parent		599		$ 600
Credit Default Swap
Commitments and Contingencies Disclosure [Line Items]
Derivative, Notional Amount	323,800	341,700
Commitments to Extend Credit
Commitments and Contingencies Disclosure [Line Items]
Commitments outstanding to extend credit	$ 4,100,000	$ 4,500,000