FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) $ in Thousands	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Available For Sale Securities [Abstract]
Available-For-Sale Securities, Debt Securities	$ 5,047,179	$ 5,229,984
Fair Value, Measurements, Recurring [Member] | Puerto Rico government obligations [Member]
Available For Sale Securities [Abstract]
Available-For-Sale Securities, Debt Securities	1,551	1,415
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Private label [Member] | Valuation Technique, Discounted Cash Flow [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Available-For-Sale Securities, Debt Securities	4,724	4,785
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Puerto Rico government obligations [Member]
Available For Sale Securities [Abstract]
Available-For-Sale Securities, Debt Securities	1,551	1,415
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]
Available-For-Sale Securities, Debt Securities	$ 1,551	$ 1,415
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Private label [Member] | Measurement Input, Discount Rate [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.164	0.161
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Private label [Member] | Measurement Input, Constant Prepayment Rate [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.000	0.000
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Minimum [Member] | Private label [Member] | Measurement Input, Loss Severity [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.002	0.001
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	0.130	0.141
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	0.213	0.258
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Private label [Member] | Measurement Input, Discount Rate [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.164	0.161
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Private label [Member] | Measurement Input, Constant Prepayment Rate [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.069	0.069
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Maximum [Member] | Private label [Member] | Measurement Input, Loss Severity [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.105	0.109
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	0.130	0.141
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	0.213	0.258
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Private label [Member] | Measurement Input, Discount Rate [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.164	0.161
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Private label [Member] | Measurement Input, Constant Prepayment Rate [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.037	0.037
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Weighted Average [Member] | Private label [Member] | Measurement Input, Loss Severity [Member] | Residential Portfolio Segment [Member]
Available For Sale Securities [Abstract]
Debt Securities, Available-for-sale, Measurement Input	0.038	0.042
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	0.130	0.141
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	0.213	0.258