DEPOSITS AND RELATED INTEREST - Narratives (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deposits [Line Items]
Weighted-average interest rate on total interest-bearing	1.03%	0.31%
Unplanned overdrafts of demand deposits that were reclassified as loans	$ 1,700	$ 1,600
Pre-arranged overdrafts lines of credit	24,500	24,200
Unamortized broker placement fees	300	200
Market value of uninsured portions collateralized by securities and loans	2,700,000	3,300,000
Amortized cost of uninsured portions collateralized by securities and loans	3,100,000	3,400,000
Accretion Of Premium From Acquisition	500	1,300	$ 1,000
Time deposits in denomnations of $250,000 or more	1,000,000	1,000,000
Deposits	16,143,467	17,784,894
Amortization of broker placement fees	106	218	537
Federal Home Loan Bank [Member] | Standby letters of credit [Member] [Member] | Asset Pledged as Collateral [Member]
Deposits [Line Items]
Credit facility amount	200,000
Government [Member]
Deposits [Line Items]
Deposits	2,800,000	3,300,000
Puerto Rico [Member]
Deposits [Line Items]
Deposits	12,933,570	14,113,874	12,338,934
Puerto Rico [Member] | Government [Member]
Deposits [Line Items]
Deposits	2,300,000	2,700,000
United States [Member]
Deposits [Line Items]
Deposits	1,623,725	1,928,749	1,622,481
United States [Member] | Government [Member]
Deposits [Line Items]
Deposits	11,600	9,600
Virgin Islands [Member]
Deposits [Line Items]
Deposits	1,586,172	1,742,271	$ 1,355,968
Virgin Islands [Member] | Government [Member]
Deposits [Line Items]
Deposits	$ 442,800	$ 568,400