FAIR VALUE DISCLOSURES OF FINANCIAL ASSETS AND LIABILITIES - Schedule of Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	$ 4,496,087	$ 5,205,311
Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets	102,196	5,153
Liabilities measured at fair value on a recurring basis:
Other liabilities	118,139	23,291
Assets measured at fair value on a nonrecurring basis:
Total assets	4,598,283	5,210,464
Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	358	2,320
Total assets	82,197	126,187
CMO
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	557,655	575,766
CMO | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	557,655	575,766
FNMA MBS
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	3,592,458	4,245,684
FNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	3,592,458	4,245,684
FHLMC MBS
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	116,396	145,528
FHLMC MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	116,396	145,528
GNMA MBS
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	39,161	17,936
GNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	39,161	17,936
GSE agency notes
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	190,417	220,397
GSE agency notes | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	190,417	220,397
Other investments | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	21,064	10,518
Loans held for sale | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans, held for sale	60,775	113,349
Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets	0	0
Liabilities measured at fair value on a recurring basis:
Other liabilities	0	0
Assets measured at fair value on a nonrecurring basis:
Total assets	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	0	0
Total assets	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | CMO | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | FNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | FHLMC MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | GNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | GSE agency notes | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | Other investments | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	0	0
Quoted Prices in Active Markets for Identical Asset (Level 1) | Loans held for sale | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans, held for sale	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets	102,109	5,153
Liabilities measured at fair value on a recurring basis:
Other liabilities	100,579	3,039
Assets measured at fair value on a nonrecurring basis:
Total assets	4,598,196	5,210,464
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	0	0
Total assets	60,775	113,349
Significant Other Observable Inputs (Level 2) | CMO | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	557,655	575,766
Significant Other Observable Inputs (Level 2) | FNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	3,592,458	4,245,684
Significant Other Observable Inputs (Level 2) | FHLMC MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	116,396	145,528
Significant Other Observable Inputs (Level 2) | GNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	39,161	17,936
Significant Other Observable Inputs (Level 2) | GSE agency notes | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	190,417	220,397
Significant Other Observable Inputs (Level 2) | Other investments | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	0	0
Significant Other Observable Inputs (Level 2) | Loans held for sale | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans, held for sale	60,775	113,349
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets	87	0
Liabilities measured at fair value on a recurring basis:
Other liabilities	17,560	20,252
Assets measured at fair value on a nonrecurring basis:
Total assets	87	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	358	2,320
Total assets	21,422	12,838
Significant Unobservable Inputs (Level 3) | CMO | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Significant Unobservable Inputs (Level 3) | FNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Significant Unobservable Inputs (Level 3) | FHLMC MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Significant Unobservable Inputs (Level 3) | GNMA MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Significant Unobservable Inputs (Level 3) | GSE agency notes | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Significant Unobservable Inputs (Level 3) | Other investments | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	21,064	10,518
Significant Unobservable Inputs (Level 3) | Loans held for sale | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans, held for sale	$ 0	$ 0