FAIR VALUE DISCLOSURES OF FINANCIAL ASSETS AND LIABILITIES - Schedule of Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	$ 3,691,541	$ 4,093,060
Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets, fair value	203,106	156,993
Liabilities measured at fair value on a recurring basis:
Other liabilities	211,303	173,622
Assets measured at fair value on a nonrecurring basis:
Total assets measured at fair value	3,894,647	4,250,053
Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	298	833
Total assets measured at fair value	58,697	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	203,083	156,912
Liabilities measured at fair value on a recurring basis:
Other liabilities	196,821	156,520
Assets measured at fair value on a nonrecurring basis:
Total assets measured at fair value	3,894,624	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	36,658	42,985
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Other assets, fair value	23	81
Liabilities measured at fair value on a recurring basis:
Other liabilities	14,482	17,102
Assets measured at fair value on a nonrecurring basis:
Total assets measured at fair value	23	81
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other real estate owned	298	833
Total assets measured at fair value	22,039	26,953
Other investments | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Other investments	21,741	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	21,741	26,120
Loans held for sale | Fair Value, Measurements, Nonrecurring
Assets measured at fair value on a nonrecurring basis:
Loans held for sale	36,658	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	36,658	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	454,664	506,380
Collateralized mortgage obligation (CMO) | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	454,664	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	454,664	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	2,913,412	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	2,913,412	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	2,913,412	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	110,719	121,999
Freddie Mac (FHLMC) MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	110,719	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	110,719	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	42,751	36,138
Ginnie Mae (GNMA) MBS | Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Investment securities available-for-sale	42,751	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	42,751	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	169,995	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	169,995	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	169,995	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