DEBT SECURITIES - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Investments [Line Items]
Fair value	$ 5,229,984,000	$ 5,599,520,000
Gross Unrealized Losses	633,049,000	798,466,000
Available-for-sale, allowance for credit losses	511,000	458,000
Allowance for credit losses, Held-to-Maturity securities	2,197,000	8,286,000
Provision for credit loss expense	(6,069,000)	(719,000)	$ (410,000)
Debt Securities, Held-to-maturity	354,178,000	437,537,000
Accrued interest receivable	77,716,000	69,730,000
Securities Held To Maturity, Purchased	0	289,900,000
Interest income on available for sale debt securities	78,300,000	86,100,000	62,700,000
Interest income, held to maturity securities	20,900,000	15,500,000	8,800,000
Held to maturity securities classified as cash and cash equivalents	0	0
Past Due [Member]
Schedule Of Investments [Line Items]
Debt Securities, Held-to-maturity	$ 0	0
FICO Score, Greater than 700 [Member] | LTV Less than 80 Percent [Member] | Private label [Member]
Schedule Of Investments [Line Items]
Loan To Value Coverage Percentage	80.00%
Municipal Bonds [Member]
Schedule Of Investments [Line Items]
Debt Securities, Held-to-maturity, Reduction, Amount Refinanced	$ 46,500,000
Puerto Rico government obligations [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses	400,000	400,000
Residential MBS [Member]
Schedule Of Investments [Line Items]
Fair value	2,633,161,000	2,941,458,000
Gross Unrealized Losses	436,055,000	514,499,000
Available-for-sale, allowance for credit losses	116,000	83,000
Allowance for credit losses, Held-to-Maturity securities	0	0
Debt Securities, Held-to-maturity	146,468,000	166,739,000
Residential MBS [Member] | Private label [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses	$ 100,000	100,000
Residential MBS [Member] | SOFR [Member] | Private label [Member]
Schedule Of Investments [Line Items]
Spread on variable rate	0.26161%
Debt Instrument Description Of Variable Rate Basis	3-month CME Term SOFR
MBS And Government Obligations Held By International Banking Entities [Member]
Schedule Of Investments [Line Items]
Interest income on available for sale debt securities	$ 39,100,000	40,700,000	25,700,000
Interest income, held to maturity securities	20,500,000	15,400,000	8,800,000
Available-for-sale Securities [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses	511,000	458,000	1,105,000	$ 1,310,000
Provision For Other Credit Losses Previous Expected Credit Losses	(20,000)	434,000	136,000
Charge-offs	(33,000)	213,000	69,000
Accrued interest receivable	10,600,000	11,100,000
Available-for-sale Securities [Member] | Puerto Rico government obligations [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses	395,000	375,000	308,000	308,000
Provision For Other Credit Losses Previous Expected Credit Losses	(20,000)	(67,000)	0
Charge-offs	0	0	0
Available-for-sale Securities [Member] | Residential MBS [Member] | Private label [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses	116,000	83,000	797,000	$ 1,002,000
Provision For Other Credit Losses Previous Expected Credit Losses	0	501,000	136,000
Charge-offs	(33,000)	213,000	$ 69,000
Held-to-maturity Securities [Member]
Schedule Of Investments [Line Items]
Accrued interest receivable	$ 4,800,000	$ 5,500,000