FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets:
Investment securities available for sale	$ 3,294,649	$ 2,123,525
Fair Value, Measurements, Recurring [Member]
Assets:
Equity Securities	1,475	1,428
Fair Value, Measurements, Recurring [Member] | Other Available For Sale Securities [Member]
Assets:
Investment securities available for sale	650	500
Fair Value, Measurements, Recurring [Member] | U S Treasury Securities [Member]
Assets:
Investment securities available for sale	7,531	7,479
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Noncallable
Assets:
Investment securities available for sale	74,837	146,777
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Callable
Assets:
Investment securities available for sale	3,195,869	1,950,331
Fair Value, Measurements, Recurring [Member] | Puerto Rico Government obligations [Member]
Assets:
Investment securities available for sale	6,923	7,322
Fair Value, Measurements, Recurring [Member] | Private label [Member]
Assets:
Investment securities available for sale	8,839	11,116
Fair Value, Measurements, Recurring [Member] | Interest Rate Swap [Member]
Assets:
Asset Derivative	1,762	0
Derivatives, included in liabilities:
Liability Derivatives	1,789	0
Fair Value, Measurements, Recurring [Member] | Interest Rate Cap [Member] | Purchase
Assets:
Asset Derivative	1	11
Fair Value, Measurements, Recurring [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Liability Derivatives	1	11
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
Assets:
Asset Derivative	951	341
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member]
Assets:
Asset Derivative	20	20
Fair Value, Measurements, Recurring [Member] | Forward Contracts [Member]
Assets:
Asset Derivative	364	0
Derivatives, included in liabilities:
Liability Derivatives	31	138
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member]
Assets:
Equity Securities	1,475	1,428
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Other Available For Sale Securities [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | U S Treasury Securities [Member]
Assets:
Investment securities available for sale	7,531	7,479
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | US Government Agencies Debt Securities [Member] | Noncallable
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | US Government Agencies Debt Securities [Member] | Callable
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Puerto Rico Government obligations [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Private label [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Interest Rate Swap [Member]
Assets:
Asset Derivative	0	0
Derivatives, included in liabilities:
Liability Derivatives	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Interest Rate Cap [Member] | Purchase
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Liability Derivatives	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Interest Rate Lock Commitments [Member]
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Loan Origination Commitments [Member]
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Forward Contracts [Member]
Assets:
Asset Derivative	0	0
Derivatives, included in liabilities:
Liability Derivatives	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member]
Assets:
Equity Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Other Available For Sale Securities [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | U S Treasury Securities [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | US Government Agencies Debt Securities [Member] | Noncallable
Assets:
Investment securities available for sale	74,837	146,777
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | US Government Agencies Debt Securities [Member] | Callable
Assets:
Investment securities available for sale	3,195,869	1,950,331
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Puerto Rico Government obligations [Member]
Assets:
Investment securities available for sale	4,016	4,348
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Private label [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Swap [Member]
Assets:
Asset Derivative	1,762	0
Derivatives, included in liabilities:
Liability Derivatives	1,789	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Purchase
Assets:
Asset Derivative	1	11
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Liability Derivatives	1	11
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Lock Commitments [Member]
Assets:
Asset Derivative	951	341
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Loan Origination Commitments [Member]
Assets:
Asset Derivative	20	20
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Forward Contracts [Member]
Assets:
Asset Derivative	364	0
Derivatives, included in liabilities:
Liability Derivatives	31	138
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member]
Assets:
Equity Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Other Available For Sale Securities [Member]
Assets:
Investment securities available for sale	650	500
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | U S Treasury Securities [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | US Government Agencies Debt Securities [Member] | Noncallable
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | US Government Agencies Debt Securities [Member] | Callable
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Puerto Rico Government obligations [Member]
Assets:
Investment securities available for sale	2,907	2,974
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Private label [Member]
Assets:
Investment securities available for sale	8,839	11,116
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Interest Rate Swap [Member]
Assets:
Asset Derivative	0	0
Derivatives, included in liabilities:
Liability Derivatives	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Interest Rate Cap [Member] | Purchase
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Liability Derivatives	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Interest Rate Lock Commitments [Member]
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Loan Origination Commitments [Member]
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Forward Contracts [Member]
Assets:
Asset Derivative	0	0
Derivatives, included in liabilities:
Liability Derivatives	$ 0	$ 0