FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Investment securities available for sale	$ 1,905,230	$ 1,942,568
Fair Value, Measurements, Recurring [Member]
Assets:
Equity Securities	425	418
Fair Value, Measurements, Recurring [Member] | Other Available For Sale Securities [Member]
Assets:
Investment securities available for sale	500	500
Fair Value, Measurements, Recurring [Member] | U S Treasury Securities [Member]
Assets:
Investment securities available for sale	7,485	7,456
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Noncallable
Assets:
Investment securities available for sale	325,949	319,124
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Callable
Assets:
Investment securities available for sale	1,550,965	1,594,622
Fair Value, Measurements, Recurring [Member] | Puerto Rico Government obligations [Member]
Assets:
Investment securities available for sale	6,980	6,952
Fair Value, Measurements, Recurring [Member] | Private label MBS [Member]
Assets:
Investment securities available for sale	13,351	13,914
Fair Value, Measurements, Recurring [Member] | Interest Rate Cap [Member] | Purchase
Assets:
Asset Derivative	334	623
Fair Value, Measurements, Recurring [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Liability Derivatives	332	617
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
Assets:
Asset Derivative	247	383
Fair Value, Measurements, Recurring [Member] | Forward loan sales commitments [Member]
Assets:
Asset Derivative	17	12
Fair Value, Measurements, Recurring [Member] | Forward Contracts [Member]
Derivatives, included in liabilities:
Liability Derivatives	256	383
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member]
Assets:
Equity Securities	425	418
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	7,485	7,456
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 MBS [Member]
Assets:
Investment securities available for sale	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] | Forward loan sales commitments [Member]
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Forward Contracts [Member]
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	325,949	319,124
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | US Government Agencies Debt Securities [Member] | Callable
Assets:
Investment securities available for sale	1,550,965	1,594,622
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Puerto Rico Government obligations [Member]
Assets:
Investment securities available for sale	4,125	4,128
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Private label MBS [Member]
Assets:
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Purchase
Assets:
Asset Derivative	334	623
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Liability Derivatives	332	617
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Lock Commitments [Member]
Assets:
Asset Derivative	247	383
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Forward loan sales commitments [Member]
Assets:
Asset Derivative	17	12
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Forward Contracts [Member]
Derivatives, included in liabilities:
Liability Derivatives	256	383
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	500	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	2,855	2,824
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Private label MBS [Member]
Assets:
Investment securities available for sale	13,351	13,914
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] | Forward loan sales commitments [Member]
Assets:
Asset Derivative	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Forward Contracts [Member]
Derivatives, included in liabilities:
Liability Derivatives	$ 0	$ 0