LOANS AND ALLOWANCE FOR LOAN LOSSES - Summary of Information Pertaining to Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impaired Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 29,291	$ 17,952	$ 14,202
Troubled debt restructurings not included above	11,646	9,323	13,599
Total impaired loans	40,937	27,275	27,801
Interest income recognized on impaired loans	1,023	827	1,867
Foregone interest income on impaired loans	882	853	950
Purchased Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	45,023	24,107	15,428
Troubled debt restructurings not included above	17,963	18,740	20,472
Total impaired loans	62,986	42,847	35,900
Interest income recognized on impaired loans	3,108	2,203	1,625
Foregone interest income on impaired loans	$ 3,218	$ 1,483	$ 1,239