LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loans Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 20,201,079	$ 19,855,253
Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,632,836	2,679,403
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	259,797	384,037
Indirect automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	47,108	108,648
Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	852,823	1,038,924
Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	497,093	509,151
Premium finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,007,334	1,023,479
Real estate – construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,236,686	2,086,438
Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,865,389	7,604,867
Real estate – residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 4,802,013	$ 4,420,306