FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	$ 5,175,803	$ 5,599,520
Residential Mortgage Backed Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	2,580,395	2,941,458
MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	2,726,042	3,104,591
Fair Value, Measurements, Recurring [Member]
Assets Fair Value Disclosure [Abstract]
Equity securities	4,775	4,861
Derivative Assets	360	633
Derivative Liabilities [Abstract]
Derivative Liabilities	170	476
Fair Value, Measurements, Recurring [Member] | U S Treasury Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	140,723	138,875
Fair Value, Measurements, Recurring [Member] | Government Agencies Debt Securities [Member] | Noncallable [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	430,515	389,787
Fair Value, Measurements, Recurring [Member] | Government Agencies Debt Securities [Member] | Call Option [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	1,877,075	1,963,566
Fair Value, Measurements, Recurring [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	2,726,042	3,104,591
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	1,448	2,201
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	0	500
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member]
Assets Fair Value Disclosure [Abstract]
Equity securities	4,775	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]
Available-For-Sale Securities, Debt Securities	140,723	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]
Available-For-Sale Securities, Debt 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, Debt Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt 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, Debt Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 1 [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member]
Assets Fair Value Disclosure [Abstract]
Equity securities	0	0
Derivative Assets	360	633
Derivative Liabilities [Abstract]
Derivative Liabilities	170	476
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, Debt 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, Debt Securities	430,515	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]
Available-For-Sale Securities, Debt Securities	1,877,075	1,963,566
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	2,721,124	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]
Available-For-Sale Securities, Debt Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 2 [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member]
Assets Fair Value Disclosure [Abstract]
Equity securities	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]
Available-For-Sale Securities, Debt 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, Debt 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, Debt Securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | MBS [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	4,918	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]
Available-For-Sale Securities, Debt Securities	1,448	2,201
Fair Value, Measurements, Recurring [Member] | Fair Value Inputs Level 3 [Member] | Other Debt Obligations [Member]
Assets Fair Value Disclosure [Abstract]
Available-For-Sale Securities, Debt Securities	$ 0	$ 500