LOANS - Purchased Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans	$ 917,126	$ 1,069,191
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans	917,126	1,069,191
Purchased Loans | Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans	80,895	96,537
Purchased Loans | Real estate – construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans	68,583	81,368
Purchased Loans | Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans	500,169	576,355
Purchased Loans | Real estate – residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans	264,312	310,277
Purchased Loans | Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans	$ 3,167	$ 4,654