LOANS AND ALLOWANCE FOR CREDIT LOSSES - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Total Loans	$ 20,600,260	$ 20,269,303
Loans 90 Days or More Past Due and Still Accruing	15,811	16,988
Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	270,156	272,839
Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	80,636	82,850
Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	31,013	34,281
Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	158,507	155,708
Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	20,330,104	19,996,464
Commercial, financial and agricultural
Financing Receivable, Past Due [Line Items]
Total Loans	2,758,716	2,688,929
Loans 90 Days or More Past Due and Still Accruing	3,925	5,310
Commercial, financial and agricultural | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	30,656	26,195
Commercial, financial and agricultural | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	15,809	11,023
Commercial, financial and agricultural | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	8,410	5,439
Commercial, financial and agricultural | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	6,437	9,733
Commercial, financial and agricultural | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	2,728,060	2,662,734
Consumer
Financing Receivable, Past Due [Line Items]
Total Loans	232,993	241,552
Loans 90 Days or More Past Due and Still Accruing	0	0
Consumer | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	4,251	3,690
Consumer | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	2,341	2,155
Consumer | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	1,548	1,037
Consumer | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	362	498
Consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	228,742	237,862
Indirect automobile
Financing Receivable, Past Due [Line Items]
Total Loans	24,022	34,257
Loans 90 Days or More Past Due and Still Accruing	0	0
Indirect automobile | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	260	248
Indirect automobile | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	82	153
Indirect automobile | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	60	17
Indirect automobile | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	118	78
Indirect automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	23,762	34,009
Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Total Loans	891,336	818,728
Loans 90 Days or More Past Due and Still Accruing	0	0
Mortgage warehouse | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Mortgage warehouse | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Mortgage warehouse | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Mortgage warehouse | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Mortgage warehouse | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	891,336	818,728
Municipal
Financing Receivable, Past Due [Line Items]
Total Loans	477,567	492,668
Loans 90 Days or More Past Due and Still Accruing	0	0
Municipal | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Municipal | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Municipal | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Municipal | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Municipal | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	477,567	492,668
Premium finance
Financing Receivable, Past Due [Line Items]
Total Loans	998,726	946,562
Loans 90 Days or More Past Due and Still Accruing	11,886	11,678
Premium finance | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	32,191	30,889
Premium finance | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	14,166	12,379
Premium finance | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	6,139	6,832
Premium finance | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	11,886	11,678
Premium finance | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	966,535	915,673
Real estate – construction and development
Financing Receivable, Past Due [Line Items]
Total Loans	2,264,346	2,129,187
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – construction and development | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	1,014	2,376
Real estate – construction and development | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	732	2,094
Real estate – construction and development | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	0
Real estate – construction and development | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	282	282
Real estate – construction and development | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	2,263,332	2,126,811
Real estate – commercial and farmland
Financing Receivable, Past Due [Line Items]
Total Loans	8,131,248	8,059,754
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – commercial and farmland | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	9,425	13,078
Real estate – commercial and farmland | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	1,858	5,070
Real estate – commercial and farmland | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	429	1,656
Real estate – commercial and farmland | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	7,138	6,352
Real estate – commercial and farmland | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	8,121,823	8,046,676
Real estate – residential
Financing Receivable, Past Due [Line Items]
Total Loans	4,821,306	4,857,666
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – residential | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	192,359	196,363
Real estate – residential | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	45,648	49,976
Real estate – residential | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	14,427	19,300
Real estate – residential | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	132,284	127,087
Real estate – residential | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	$ 4,628,947	$ 4,661,303