LOANS - Loans Receivable, Excluding Purchased Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 6,190,171	$ 6,046,355
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	5,051,986	4,856,514
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,387,437	1,362,508
Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	631,504	624,595
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,636,654	1,535,439
Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,080,028	1,009,461
Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 316,363	$ 324,511