LOANS AND ALLOWANCE FOR LOAN LOSSES - Loans Receivable, Purchased Loans (Details) - Purchased Loans - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 2,588,832	$ 861,595
Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	372,686	74,378
Real estate – construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	227,900	65,513
Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,337,859	468,246
Real estate – residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	623,199	250,539
Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 27,188	$ 2,919