DEPOSITS - Narratives (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deposits [Line Items]
Weighted-average interest rate on total interest-bearing	2.24%	1.03%
Unplanned overdrafts of demand deposits that were reclassified as loans	$ 1,400	$ 1,700
Pre-arranged overdrafts lines of credit	23,800	24,500
Unamortized broker placement fees	1,000	300
Market value of uninsured portions collateralized by securities and loans	3,100,000	2,700,000
Amortized cost of uninsured portions collateralized by securities and loans	3,500,000	3,100,000
Accretion Of Premium From Acquisition	200	500	$ 1,300
Time deposits in denominations of $250,000 or more	1,400,000	1,000,000
Deposits	16,555,985	16,143,467
Amortization of broker placement fees	309	106	218
Federal Home Loan Bank [Member] | Standby letters of credit [Member] [Member] | Asset Pledged as Collateral [Member]
Deposits [Line Items]
Letters of credit outstanding amount	175,000	200,000
Government [Member]
Deposits [Line Items]
Deposits	3,200,000	2,800,000
Puerto Rico [Member]
Deposits [Line Items]
Deposits	13,429,303	12,933,570	14,113,874
Puerto Rico [Member] | Government [Member]
Deposits [Line Items]
Deposits	2,700,000	2,300,000
United States [Member]
Deposits [Line Items]
Deposits	1,631,402	1,623,725	1,928,749
United States [Member] | Government [Member]
Deposits [Line Items]
Deposits	10,200	11,600
Virgin Islands [Member]
Deposits [Line Items]
Deposits	1,495,280	1,586,172	$ 1,742,271
Virgin Islands [Member] | Government [Member]
Deposits [Line Items]
Deposits	$ 449,400	$ 442,800