FAIR VALUE - Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Carrying Value
Financial assets:
Net loans	$ 7,372,106	$ 7,323,770
Financial liabilities:
Deposits	13,317,667	12,911,168
Securities sold under agreement to repurchase, short-term	300,531	324,720
Other Federal Home Loan Bank borrowings	1,864	1,888
Subordinated notes payable	3,270	3,277
Fair Value
Financial assets:
Net loans	7,321,891	7,523,024
Financial liabilities:
Deposits	13,304,381	12,911,197
Securities sold under agreement to repurchase, short-term	300,531	324,720
Other Federal Home Loan Bank borrowings	1,846	1,907
Subordinated notes payable	$ 3,270	$ 3,277