DEPOSITS - Narratives (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deposits [Line Items]
Weighted-average interest rate on total interest-bearing	0.31%	0.55%
Unplanned overdrafts of demand deposits that were reclassified as loans	$ 1,600	$ 800
Pre-arranged overdrafts lines of credit	24,200	26,000
Brokered CDs	100,417	216,172
Unamortized broker placement fees	200	400
Deposits	17,784,894	15,317,383
Market value of uninsured portions collateralized by securities and loans	3,300,000	2,100,000
Amortized cost of uninsured portions collateralized by securities and loans	3,400,000	2,000,000
Accretion Of Premium From Acquisition	1,300	1,000
Letters of credit issued by the FHLB as pledges for public deposits in the Virgin Islands	2,100,000	2,500,000
Amortization Of Broker Placement Fees	218	537	$ 732
Time deposits in denomnations of $250,000 or more	1,000,000	1,000,000
Federal Home Loan Bank [Member]
Deposits [Line Items]
Letters of credit issued by the FHLB as pledges for public deposits in the Virgin Islands	1,800,000	2,200,000
Government [Member]
Deposits [Line Items]
Deposits	3,300,000	2,100,000
Puerto Rico [Member]
Deposits [Line Items]
Brokered CDs	34,200	109,000	243,400
Deposits	14,113,874	12,338,934	6,422,864
Puerto Rico [Member] | Government [Member]
Deposits [Line Items]
Deposits	2,700,000	1,800,000
United States [Member]
Deposits [Line Items]
Brokered CDs	66,200	107,100	191,700
Deposits	1,928,749	1,622,481	1,661,657
United States [Member] | Government [Member]
Deposits [Line Items]
Deposits	9,600	9,700
Virgin Islands [Member]
Deposits [Line Items]
Deposits	1,742,271	1,355,968	$ 1,263,908
Virgin Islands [Member] | Government [Member]
Deposits [Line Items]
Deposits	$ 568,400	$ 280,200