INVESTMENT SECURITIES - Aggregate amortized cost and approximate market value of investment securities available for sale by contractual maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Total Amortized cost	$ 6,534,503	$ 4,584,851
Total investment securities available for sale, at fair value	6,453,761	4,647,019
United States And Puerto Rico Government Obligations And Other Debt Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	500
Amortized cost After 1 to 5 years	2,027,341
Amortized cost After 5 to 10 years	403,785
Amortized cost After 10 years	19,362
Total Amortized cost	2,450,988
Fair value Due within one year	500
Fair value After 1 to 5 years	1,996,852
Fair value After 5 to 10 years	393,104
Fair value After 10 years	18,862
Total investment securities available for sale, at fair value	2,409,318
Mortgage Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Total Amortized cost	4,083,515	3,393,768
Total investment securities available for sale, at fair value	$ 4,044,443	$ 3,455,796

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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