FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	$ 5,589,256	$ 5,599,520
Residential Mortgage Backed Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	2,896,655	2,941,458
MBS [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	3,055,421	3,104,591
Fair Value, Measurements, Recurring [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	4,926	4,861
Derivative Assets	628	633
Derivative Liabilities [Abstract]
Derivative Liabilities	645	476
Fair Value, Measurements, Recurring [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	140,422	138,875
Fair Value, Measurements, Recurring [Member] | Government Agencies Debt Securities [Member] | Noncallable [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	428,675	389,787
Fair Value, Measurements, Recurring [Member] | Government Agencies Debt Securities [Member] | Call Option [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	1,962,535	1,963,566
Fair Value, Measurements, Recurring [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	3,055,421	3,104,591
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	2,203	2,201
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	0	500
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	4,926	4,861
Derivative Assets	0	0
Derivative Liabilities [Abstract]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	140,422	138,875
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Government Agencies Debt Securities [Member] | Noncallable [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	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]
Debt Securities, Available-for-sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	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]
Debt Securities, Available-for-sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	0	0
Derivative Assets	628	633
Derivative Liabilities [Abstract]
Derivative Liabilities	645	476
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	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]
Debt Securities, Available-for-sale	428,675	389,787
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Government Agencies Debt Securities [Member] | Call Option [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	1,962,535	1,963,566
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	3,050,019	3,098,797
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member]
Assets Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	0	0
Derivative Assets	0	0
Derivative Liabilities [Abstract]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	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]
Debt Securities, Available-for-sale	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]
Debt Securities, Available-for-sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	5,402	5,794
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	2,203	2,201
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	$ 0	$ 500