INVESTMENT SECURITIES - Additional Information (Detail) - USD ($)		12 Months Ended
	Sep. 01, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Investments [Line Items]
Proceeds from sales of available-for-sale securities		$ 0	$ 1,195,250,000	$ 0
Available-for-sale realized gains			13,300,000
Available-for-sale gross realized losses			100,000
Available-for-sale net gain			13,200,000
Fair value		6,453,761,000	4,647,019,000
Gross unrealized loss		108,537,000	5,517,000
Available-for-sale, allowance for credit losses		1,105,000	1,310,000
Provision For Other Credit Losses Previous Expected Credit Losses		(136,000)
Charge-offs		69,000
Allowance for credit losses, Held-to-Maturity securities		$ 8,571,000	8,845,000
Purchase price of debt securities at acquisition (initial fair value)	$ 55,500,000
Debt Securities, Held-to-maturity, Threshold Period Past Due		30 days
Interest Receivable		$ 61,507,000	69,505,000
Past Due [Member]
Schedule Of Investments [Line Items]
Debt Securities, Held-to-maturity		0	0
Private label [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses			1,002,000	0
Provision For Other Credit Losses Previous Expected Credit Losses			1,641,000
Charge-offs			331,000
Municipal Bonds [Member] | Puerto Rico [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses		8,600,000	8,800,000
Allowance for credit losses, Held-to-Maturity securities		8,571,000	8,845,000	0
Initial allowance on PCD debt securities	$ 1,300,000	0	1,269,000
Provision for credit loss expense		(274,000)	(558,000)
Debt Securities, Held-to-maturity		178,133,000	189,488,000
Debt Securities Available For Sale Allowance For Credit Loss Period Increase Decrease		(200,000)
Municipal Bonds [Member] | Puerto Rico [Member] | ASC 326 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Schedule Of Investments [Line Items]
Impact of adopting ASC 326 on Held-to-maturity securities			0	8,134,000
Puerto Rico government obligations [Member]
Schedule Of Investments [Line Items]
Available-for-sale, allowance for credit losses		308,000	308,000	0
Provision For Other Credit Losses Previous Expected Credit Losses		0	308,000
Charge-offs		0	0
Puerto Rico government obligations [Member] | Residential Mortgage Backed Securities [Member]
Schedule Of Investments [Line Items]
Fair value		2,900,000
Gross unrealized loss		700,000
Provision For Other Credit Losses No Previous Expected Credit Losses		300,000
MBS [Member]
Schedule Of Investments [Line Items]
Fair value		4,044,443,000	3,455,796,000
Gross unrealized loss		66,477,000	3,951,000
Available-for-sale, allowance for credit losses		797,000	1,002,000
MBS [Member] | Private label [Member]
Schedule Of Investments [Line Items]
Fair value		7,200,000
Gross unrealized loss		2,800,000
Available-for-sale, allowance for credit losses		797,000	1,000,000.0	$ 0
Provision For Other Credit Losses Previous Expected Credit Losses		(136,000)	1,333,000
Charge-offs		$ 69,000	$ 331,000
Available-for-sale Securities [Member]
Schedule Of Investments [Line Items]
Percentage Of Debt Securities Government And Government Sponsored Agencies		99.00%	99.00%
Interest Receivable		$ 10,100,000	$ 8,500,000
Available-for-sale Securities [Member] | MBS [Member] | Private label [Member] | FICO Score, Greater than 700 [Member] | LTV Less than 80 Percent [Member]
Schedule Of Investments [Line Items]
Financing Receivable, Credit Quality, Additional Information		The underlying collateral are fixed-rate, single-family residential mortgage loans in the United States with original FICO scores over 700 and moderate loan-to-value ratios (under 80%), as well as moderate delinquency levels.
Available-for-sale Securities [Member] | MBS [Member] | Private label [Member] | London Interbank Offered Rate (LIBOR) [Member]
Schedule Of Investments [Line Items]
Loans Receivable, Description of Variable Rate Basis		The interest rate on these private-label MBS is variable, tied to 3-month LIBOR, and limited to the weighted-average coupon on the underlying collateral.
Held-to-maturity Securities [Member]
Schedule Of Investments [Line Items]
Interest Receivable		$ 3,400,000	3,600,000
Held-to-maturity Securities [Member] | Municipal Bonds [Member] | Puerto Rico [Member]
Schedule Of Investments [Line Items]
Provision for credit loss expense			$ (600,000)