FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale	$ 6,453,761	$ 4,647,019
Fair Value, Measurements, Recurring [Member] | Private label [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale	7,234	8,428
Fair Value, Measurements, Recurring [Member] | Puerto Rico government obligations [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale	2,850	2,899
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Private label [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale	7,234	8,428
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Private label [Member] | Valuation Technique, Discounted Cash Flow [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale	7,234	8,428
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Puerto Rico government obligations [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale	2,850	2,899
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Puerto Rico government obligations [Member] | Valuation Technique, Discounted Cash Flow [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale	$ 2,850	$ 2,899
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Private label [Member] | Measurement Input, Discount Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.129	0.122
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Private label [Member] | Measurement Input, Constant Prepayment Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.076	0.012
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Private label [Member] | Measurement Input, Loss Severity [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.002	0.026
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Puerto Rico government obligations [Member] | Measurement Input, Discount Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.079	0.079
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Puerto Rico government obligations [Member] | Measurement Input, Loss Severity [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.086	0.124
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Private label [Member] | Measurement Input, Discount Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.129	0.122
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Private label [Member] | Measurement Input, Constant Prepayment Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.249	0.188
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Private label [Member] | Measurement Input, Loss Severity [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.157	0.223
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Puerto Rico government obligations [Member] | Measurement Input, Discount Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.079	0.079
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Puerto Rico government obligations [Member] | Measurement Input, Loss Severity [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.086	0.124
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Private label [Member] | Measurement Input, Discount Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.129	0.122
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Private label [Member] | Measurement Input, Constant Prepayment Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.152	0.121
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Private label [Member] | Measurement Input, Loss Severity [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.076	0.102
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Puerto Rico government obligations [Member] | Measurement Input, Discount Rate [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.079	0.079
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Puerto Rico government obligations [Member] | Measurement Input, Loss Severity [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.086	0.124