COMMITMENTS AND CONTINGENCIES - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Commitments and Contingencies Disclosure [Line Items]
Reserves for unfunded commitments	$ 17,000		$ 17,000		$ 18,400
Loans and Leases Receivable, Commitments, Fixed Rates			111,500		126,300
Loans and Leases Receivable, Commitments, Variable Rates			$ 4,400,000		$ 4,200,000
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 1 month 6 days		31 years 7 months 6 days
Letters of credit issued to guarantee performance of a client to a third party	32,400		$ 32,400		$ 31,500
Derivative, Notional Amount	20,027,711		20,027,711		19,828,103
Litigation Settlement, Expense	0	$ 0	0	$ 3,300
Estimated Litigation Liability	0		0		0
Credit Default Swap
Commitments and Contingencies Disclosure [Line Items]
Derivative, Notional Amount	318,100		318,100		379,300
Commitments to Extend Credit
Commitments and Contingencies Disclosure [Line Items]
Commitments outstanding to extend credit	$ 4,500,000		$ 4,500,000		$ 4,400,000