FAIR VALUE DISCLOSURES AND REPORTING, THE FAIR VALUE OPTION AND FAIR VALUE MEASUREMENTS - Fair Values of Off-Balance Sheet Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets:
Cash and cash equivalents	$ 197,632	$ 145,315
Securities available-for-sale	1,141,971	1,257,101
Loans held for sale	5,960	4,443
Securities held-to-maturity	582,592	642,097
Net loans held for investment	5,036,235	3,735,240
Accrued interest receivable	30,542	27,723
Liabilities:
Noninterest-bearing	1,967,661	1,630,203
Interest-bearing deposits	4,512,364	3,864,201
Subordinated debentures	128,300	145,027
Accrued interest payable	13,800	3,324
Quoted Prices (Level 1)
Assets:
Cash and cash equivalents	197,632	145,315
Securities available-for-sale	124,694	123,854
Loans held for sale	0	0
Securities held-to-maturity	0	0
Net loans held for investment	0	0
Accrued interest receivable	0	0
Liabilities:
Noninterest-bearing	0	0
Interest-bearing deposits	0	0
Subordinated debentures	0	0
FHLB and other borrowings	0	0
Accrued interest payable	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Securities available-for-sale	997,753	1,118,099
Loans held for sale	5,960	4,443
Securities held-to-maturity	582,592	642,097
Net loans held for investment	0	0
Accrued interest receivable	8,112	9,757
Liabilities:
Noninterest-bearing	1,967,661	1,630,203
Interest-bearing deposits	4,225,829	3,505,990
Subordinated debentures	0	0
FHLB and other borrowings	302,000	130,100
Accrued interest payable	13,800	3,324
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Securities available-for-sale	19,524	15,148
Loans held for sale	0	0
Securities held-to-maturity	0	0
Net loans held for investment	4,851,597	3,681,313
Accrued interest receivable	22,430	17,966
Liabilities:
Noninterest-bearing	0	0
Interest-bearing deposits	0	0
Subordinated debentures	106,391	133,816
FHLB and other borrowings	0	0
Accrued interest payable	0	0
Carrying Amount
Assets:
Cash and cash equivalents	197,632	145,315
Securities available-for-sale	1,141,971	1,257,101
Loans held for sale	5,960	4,443
Securities held-to-maturity	658,524	691,484
Net loans held for investment	5,036,235	3,735,240
Accrued interest receivable	30,542	27,723
Liabilities:
Noninterest-bearing	1,967,661	1,630,203
Interest-bearing deposits	4,512,364	3,864,201
Subordinated debentures	128,300	145,027
FHLB and other borrowings	302,000	130,100
Accrued interest payable	13,800	3,324
Estimated Fair Value
Assets:
Cash and cash equivalents	197,632	145,315
Securities available-for-sale	1,141,971	1,257,101
Loans held for sale	5,960	4,443
Securities held-to-maturity	582,592	642,097
Net loans held for investment	4,851,597	3,681,313
Accrued interest receivable	30,542	27,723
Liabilities:
Noninterest-bearing	1,967,661	1,630,203
Interest-bearing deposits	4,225,829	3,505,990
Subordinated debentures	106,391	133,816
FHLB and other borrowings	302,000	130,100
Accrued interest payable	13,800	3,324
Interest rate swap contracts
Assets:
Interest rate swaps	14,869	12,825
Liabilities:
Interest rate swaps	14,880	12,825
Interest rate swap contracts | Quoted Prices (Level 1)
Assets:
Interest rate swaps	0	0
Liabilities:
Interest rate swaps	0	0
Interest rate swap contracts | Significant Other Observable Inputs (Level 2)
Assets:
Interest rate swaps	14,869	12,825
Liabilities:
Interest rate swaps	14,869	12,825
Interest rate swap contracts | Significant Unobservable Inputs (Level 3)
Assets:
Interest rate swaps	0	0
Liabilities:
Interest rate swaps	11	0
Interest rate swap contracts | Carrying Amount
Assets:
Interest rate swaps	14,869	12,825
Liabilities:
Interest rate swaps	14,880	12,825
Interest rate swap contracts | Estimated Fair Value
Assets:
Interest rate swaps	14,869	12,825
Liabilities:
Interest rate swaps	$ 14,880	$ 12,825