LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loans by Class Modified as Troubled Debt Restructurings (Details) - Loans Excluding Purchased Loan $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) contract branch	Mar. 31, 2021 USD ($) contract branch	Dec. 31, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	8	11
Troubled debt restructurings principal balances	$ 1,139	$ 8,693
Financing Receivables, 30 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	35	38
Troubled debt restructurings principal balances	$ 4,414	$ 6,159
Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	466		494
Troubled debt restructurings principal balances	$ 44,486		$ 65,582
Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	109		120
Troubled debt restructurings principal balances	$ 5,464		$ 11,006
Commercial, financial and agricultural
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	0	4
Troubled debt restructurings principal balances	$ 0	$ 463
Commercial, financial and agricultural | Financing Receivables, 30 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	0	3
Troubled debt restructurings principal balances	$ 0	$ 56
Commercial, financial and agricultural | Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	9		12
Troubled debt restructurings principal balances	$ 868		$ 1,286
Commercial, financial and agricultural | Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	4		6
Troubled debt restructurings principal balances	$ 72		$ 83
Premium finance
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	5	0
Troubled debt restructurings principal balances	$ 162	$ 0
Premium finance | Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	5
Troubled debt restructurings principal balances	$ 162
Premium finance | Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	0
Troubled debt restructurings principal balances	$ 0
Consumer installment | Financing Receivables, 30 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	1	5
Troubled debt restructurings principal balances	$ 3	$ 6
Consumer installment | Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	6		7
Troubled debt restructurings principal balances	$ 13		$ 16
Consumer installment | Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	16		17
Troubled debt restructurings principal balances	$ 31		$ 35
Indirect automobile | Financing Receivables, 30 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | branch	14	16
Troubled debt restructurings principal balances	$ 49	$ 94
Indirect automobile | Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	215		233
Troubled debt restructurings principal balances	$ 893		$ 1,037
Indirect automobile | Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	46		52
Troubled debt restructurings principal balances	$ 221		$ 273
Real estate – construction and development | Financing Receivables, 30 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	0	1
Troubled debt restructurings principal balances	$ 0	$ 1
Real estate – construction and development | Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	3		4
Troubled debt restructurings principal balances	$ 725		$ 789
Real estate – construction and development | Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	1		1
Troubled debt restructurings principal balances	$ 11		$ 13
Real estate – commercial and farmland
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	0	2
Troubled debt restructurings principal balances	$ 0	$ 7,658
Real estate – commercial and farmland | Financing Receivables, 30 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	2	2
Troubled debt restructurings principal balances	$ 1,569	$ 5,193
Real estate – commercial and farmland | Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	21		25
Troubled debt restructurings principal balances	$ 17,161		$ 35,575
Real estate – commercial and farmland | Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	4		5
Troubled debt restructurings principal balances	$ 788		$ 5,924
Real estate – residential
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	3	5
Troubled debt restructurings principal balances	$ 977	$ 572
Real estate – residential | Financing Receivables, 30 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	18	11
Troubled debt restructurings principal balances	$ 2,793	$ 809
Real estate – residential | Financing Receivables, 30 Days Past Due | Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	207		213
Troubled debt restructurings principal balances	$ 24,664		$ 26,879
Real estate – residential | Financing Receivables, 30 Days Past Due | Non-Accruing Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	38		39
Troubled debt restructurings principal balances	$ 4,341		$ 4,678