DEPOSITS - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deposits [Line Items]
Weighted-average interest rate on total interest-bearing	2.18%	2.24%
Unplanned overdrafts of demand deposits that were reclassified as loans	$ 2,000	$ 1,400
Pre-arranged overdrafts lines of credit	25,600	23,800
Time deposits in denominations of $250,000 or more	1,500,000	1,400,000
Unamortized broker placement fees	1,100	1,000
Deposit accounts issued to government agencies with a carrying value	16,871,298	16,555,985
Amortized cost of uninsured portions collateralized by securities and loans	3,700,000	3,500,000
Market value of uninsured portions collateralized by securities and loans	3,300,000	3,100,000
Amortization of broker placement fees	757	309	$ 106
Federal Home Loan Bank [Member] | Standby Letters Of Credit [Member] | Asset Pledged as Collateral [Member]
Deposits [Line Items]
Letters of credit outstanding amount	175,000	175,000
Government [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	3,500,000	3,200,000
Puerto Rico [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	13,562,227	13,429,303	12,933,570
Puerto Rico [Member] | Government [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	3,100,000	2,700,000
United States [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	1,864,772	1,631,402	1,623,725
United States [Member] | Government [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	21,300	10,200
Virgin Islands [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	1,444,299	1,495,280	$ 1,586,172
Virgin Islands [Member] | Government [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	$ 424,200	$ 449,400