LOANS AND ALLOWANCE FOR LOAN LOSSES - Deferrals Related to the COVID-19 (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
COVID-19 Deferrals	$ 332,779
Deferrals as a % of total loans	2.30%
Commercial, financial and agricultural
Financing Receivable, Allowance for Credit Losses [Line Items]
COVID-19 Deferrals	$ 12,471
Deferrals as a % of total loans	0.80%
Consumer installment
Financing Receivable, Allowance for Credit Losses [Line Items]
COVID-19 Deferrals	$ 1,418
Deferrals as a % of total loans	0.50%
Indirect automobile
Financing Receivable, Allowance for Credit Losses [Line Items]
COVID-19 Deferrals	$ 8,936
Deferrals as a % of total loans	1.50%
Real estate – construction and development
Financing Receivable, Allowance for Credit Losses [Line Items]
COVID-19 Deferrals	$ 11,049
Deferrals as a % of total loans	0.70%
Real estate – commercial and farmland
Financing Receivable, Allowance for Credit Losses [Line Items]
COVID-19 Deferrals	$ 179,183
Deferrals as a % of total loans	3.40%
Real estate – residential
Financing Receivable, Allowance for Credit Losses [Line Items]
COVID-19 Deferrals	$ 119,722
Deferrals as a % of total loans	4.30%