LOANS - Purchased Loans (Details) - Purchased Loans - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 5,388,336	$ 2,588,832
Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	385,355	372,686
Real estate – construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	521,324	227,900
Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,057,384	1,337,859
Real estate – residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,285,096	623,199
Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 1,139,177	$ 27,188