FAIR VALUE MEASURES - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financial assets:
Cash and due from banks	$ 235,931	$ 230,470
Debt securities held-to-maturity	126,581	122,731
Financial liabilities:
Other borrowings	631,380	509,586
Subordinated deferrable interest debentures	130,814	130,315
Carrying Amount
Financial assets:
Cash and due from banks	235,931	230,470
Federal funds sold and interest-bearing accounts	975,321	936,834
Debt securities held-to-maturity	147,022	141,512
Loans, net	20,233,090	19,925,225
Financial liabilities:
Deposits	20,997,390	20,708,509
Other borrowings	631,380	509,586
Subordinated deferrable interest debentures	130,814	130,315
Fair Value
Financial assets:
Cash and due from banks	235,931	230,470
Federal funds sold and interest-bearing accounts	975,321	936,834
Debt securities held-to-maturity	126,581	122,731
Loans, net	19,662,474	19,332,899
Financial liabilities:
Deposits	20,945,083	20,707,463
Other borrowings	617,432	501,723
Subordinated deferrable interest debentures	141,659	141,407
Fair Value | Level 1
Financial assets:
Cash and due from banks	235,931	230,470
Federal funds sold and interest-bearing accounts	975,321	936,834
Debt securities held-to-maturity	0	0
Loans, net	0	0
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
Subordinated deferrable interest debentures	0	0
Fair Value | Level 2
Financial assets:
Cash and due from banks	0	0
Federal funds sold and interest-bearing accounts	0	0
Debt securities held-to-maturity	126,581	122,731
Loans, net	0	0
Financial liabilities:
Deposits	20,945,083	20,707,463
Other borrowings	617,432	501,723
Subordinated deferrable interest debentures	141,659	141,407
Fair Value | Level 3
Financial assets:
Cash and due from banks	0	0
Federal funds sold and interest-bearing accounts	0	0
Debt securities held-to-maturity	0	0
Loans, net	19,662,474	19,332,899
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
Subordinated deferrable interest debentures	$ 0	$ 0