FAIR VALUE DISCLOSURES OF FINANCIAL ASSETS AND LIABILITIES - Schedule of Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	$ 4,086,459	$ 4,093,060
Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets, fair value	122,163	156,993
Liabilities measured at fair value on a recurring basis:
Other liabilities	135,917	173,622
Assets measured at fair value on a nonrecurring basis:
Total assets measured at fair value	4,208,622	4,250,053
Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	1,131	833
Total assets measured at fair value	65,662	69,938
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, fair value	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 measured at fair value	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 measured at fair value	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets, fair value	122,085	156,912
Liabilities measured at fair value on a recurring basis:
Other liabilities	119,622	156,520
Assets measured at fair value on a nonrecurring basis:
Total assets measured at fair value	4,208,544	4,249,972
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 measured at fair value	39,734	42,985
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets, fair value	78	81
Liabilities measured at fair value on a recurring basis:
Other liabilities	16,295	17,102
Assets measured at fair value on a nonrecurring basis:
Total assets measured at fair value	78	81
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	1,131	833
Total assets measured at fair value	25,928	26,953
Other investments | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	24,797	26,120
Other investments | Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	0	0
Other investments | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	0	0
Other investments | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	24,797	26,120
Loans held for sale | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans held for sale	39,734	42,985
Loans held for sale | Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans held for sale	0	0
Loans held for sale | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans held for sale	39,734	42,985
Loans held for sale | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans held for sale	0	0
Collateralized mortgage obligation (CMO)
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	506,136	506,380
Collateralized mortgage obligation (CMO) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	506,136	506,380
Collateralized mortgage obligation (CMO) | Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Collateralized mortgage obligation (CMO) | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	506,136	506,380
Collateralized mortgage obligation (CMO) | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Fannie Mae (FNMA) mortgage-backed securities (MBS)
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	3,235,823	3,250,258
Fannie Mae (FNMA) mortgage-backed securities (MBS) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	3,235,823	3,250,258
Fannie Mae (FNMA) mortgage-backed securities (MBS) | Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Fannie Mae (FNMA) mortgage-backed securities (MBS) | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	3,235,823	3,250,258
Fannie Mae (FNMA) mortgage-backed securities (MBS) | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Freddie Mac (FHLMC) MBS
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	122,089	121,999
Freddie Mac (FHLMC) MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	122,089	121,999
Freddie Mac (FHLMC) MBS | Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Freddie Mac (FHLMC) MBS | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	122,089	121,999
Freddie Mac (FHLMC) MBS | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Ginnie Mae (GNMA) MBS
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	40,242	36,138
Ginnie Mae (GNMA) MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	40,242	36,138
Ginnie Mae (GNMA) MBS | Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Ginnie Mae (GNMA) MBS | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	40,242	36,138
Ginnie Mae (GNMA) MBS | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Government-sponsored enterprises (GSE) agency notes
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	182,169	178,285
Government-sponsored enterprises (GSE) agency notes | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	182,169	178,285
Government-sponsored enterprises (GSE) agency notes | Quoted Prices in Active Markets for Identical Asset (Level 1) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	0	0
Government-sponsored enterprises (GSE) agency notes | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	182,169	178,285
Government-sponsored enterprises (GSE) agency notes | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	$ 0	$ 0