FAIR VALUE - Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Carrying Value
Financial assets:
Net loans	$ 7,323,770	$ 7,355,083
Financial liabilities:
Deposits	12,911,168	11,224,974
Securities sold under agreement to repurchase, short-term	324,720	284,008
Other Federal Home Loan Bank borrowings	1,888	6,658
Subordinated notes payable	3,277	3,303
Subordinated debt held by unconsolidated subsidiary trusts	0	77,320
Fair Value
Financial assets:
Net loans	7,523,024	7,655,044
Financial liabilities:
Deposits	12,911,197	11,239,628
Securities sold under agreement to repurchase, short-term	324,720	284,008
Other Federal Home Loan Bank borrowings	1,907	6,758
Subordinated notes payable	3,277	3,303
Subordinated debt held by unconsolidated subsidiary trusts	$ 0	$ 77,320