FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	$ 1,942,568	$ 1,891,016
Fair Value, Measurements, Recurring [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	418	0
Fair Value, Measurements, Recurring [Member] | Other Available For Sale Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	500	100
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	418
Fair Value, Measurements, Recurring [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	7,456	7,401
Fair Value, Measurements, Recurring [Member] | Government Agencies Debt Securities [Member] | Noncallable [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	319,124	361,971
Fair Value, Measurements, Recurring [Member] | Government Agencies Debt Securities [Member] | Call Option [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	1,594,622	1,497,253
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	6,952	6,813
Fair Value, Measurements, Recurring [Member] | Private label MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	13,914	17,060
Fair Value, Measurements, Recurring [Member] | Interest Rate Cap [Member] | Purchase [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	623	305
Fair Value, Measurements, Recurring [Member] | Interest Rate Cap [Member] | Written [Member]
Derivative Liabilities [Abstract]
Derivative Liabilities	617	305
Fair Value, Measurements, Recurring [Member] | Forward Contracts [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	7
Derivative Liabilities [Abstract]
Derivative Liabilities	383	19
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	383	0
Fair Value, Measurements, Recurring [Member] | Forward loan sales commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	12	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	418	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Other Available For Sale Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	418
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	7,456	7,401
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Government Agencies Debt Securities [Member] | Noncallable [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Government Agencies Debt Securities [Member] | Call Option [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Private label MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Interest Rate Cap [Member] | Purchase [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Interest Rate Cap [Member] | Written [Member]
Derivative Liabilities [Abstract]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Forward Contracts [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	0
Derivative Liabilities [Abstract]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Interest Rate Lock Commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Forward loan sales commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Other Available For Sale Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Government Agencies Debt Securities [Member] | Noncallable [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	319,124	361,971
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Government Agencies Debt Securities [Member] | Call Option [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	1,594,622	1,497,253
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	4,128	4,118
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Private label MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Purchase [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	623	305
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Written [Member]
Derivative Liabilities [Abstract]
Derivative Liabilities	617	305
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Forward Contracts [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	7
Derivative Liabilities [Abstract]
Derivative Liabilities	383	19
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Lock Commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	383	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Forward loan sales commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	12	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Other Available For Sale Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	500	100
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Government Agencies Debt Securities [Member] | Noncallable [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Government Agencies Debt Securities [Member] | Call Option [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	2,824	2,695
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Private label MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available For Sale Securities	13,914	17,060
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Interest Rate Cap [Member] | Purchase [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Interest Rate Cap [Member] | Written [Member]
Derivative Liabilities [Abstract]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Forward Contracts [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	0
Derivative Liabilities [Abstract]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Interest Rate Lock Commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Forward loan sales commitments [Member]
Assets Fair Value Disclosure [Abstract]
Derivative Assets	$ 0	$ 0