LOANS AND ALLOWANCE FOR LOAN LOSSES - Loans by Class Modified as Troubled Debt Restructurings (Details) - Loans Excluding Purchased Loan $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) branch	Dec. 31, 2019 USD ($) branch
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	570	65
Troubled debt restructurings not included above | $	$ 49,381	$ 8,504
Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	34	40
Troubled debt restructurings not included above | $	$ 4,378	$ 4,193
Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	752	234
Troubled debt restructurings not included above | $	$ 78,843	$ 29,609
Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	128	95
Troubled debt restructurings not included above | $	$ 6,145	$ 5,623
Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	7	4
Troubled debt restructurings not included above | $	$ 855	$ 627
Commercial, financial and agricultural | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	1	6
Troubled debt restructurings not included above | $	$ 2	$ 87
Commercial, financial and agricultural | Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	9	5
Troubled debt restructurings not included above | $	$ 521	$ 516
Commercial, financial and agricultural | Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	11	17
Troubled debt restructurings not included above | $	$ 849	$ 335
Consumer installment
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	5	10
Troubled debt restructurings not included above | $	$ 15	$ 58
Consumer installment | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	4	5
Troubled debt restructurings not included above | $	$ 2	$ 32
Consumer installment | Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	10	4
Troubled debt restructurings not included above | $	$ 32	$ 8
Consumer installment | Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	20	27
Troubled debt restructurings not included above | $	$ 56	$ 107
Indirect automobile
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	488	0
Troubled debt restructurings not included above | $	$ 2,738	$ 0
Indirect automobile | Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	437
Troubled debt restructurings not included above | $	$ 2,277
Indirect automobile | Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	51
Troubled debt restructurings not included above | $	$ 461
Premium finance
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	0	1
Troubled debt restructurings not included above | $	$ 0	$ 157
Premium finance | Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch		1
Troubled debt restructurings not included above | $		$ 156
Premium finance | Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch		0
Troubled debt restructurings not included above | $		$ 0
Real estate – construction and development
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	1	0
Troubled debt restructurings not included above | $	$ 17	$ 0
Real estate – construction and development | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	3	1
Troubled debt restructurings not included above | $	$ 689	$ 2
Real estate – construction and development | Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	4	6
Troubled debt restructurings not included above | $	$ 506	$ 936
Real estate – construction and development | Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	5	3
Troubled debt restructurings not included above | $	$ 707	$ 253
Real estate – commercial and farmland
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	14	2
Troubled debt restructurings not included above | $	$ 31,630	$ 220
Real estate – commercial and farmland | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	4	5
Troubled debt restructurings not included above | $	$ 929	$ 1,942
Real estate – commercial and farmland | Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	28	21
Troubled debt restructurings not included above | $	$ 36,707	$ 6,732
Real estate – commercial and farmland | Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	7	8
Troubled debt restructurings not included above | $	$ 1,401	$ 2,071
Real estate – residential
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	55	48
Troubled debt restructurings not included above | $	$ 14,126	$ 7,442
Real estate – residential | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	22	23
Troubled debt restructurings not included above | $	$ 2,756	$ 2,130
Real estate – residential | Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	264	197
Troubled debt restructurings not included above | $	$ 38,800	$ 21,261
Real estate – residential | Non-Accruing Loans | Financing Receivables, 1 to 29 Days Past Due
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | branch	34	40
Troubled debt restructurings not included above | $	$ 2,671	$ 2,857