LOANS AND ALLOWANCE FOR CREDIT LOSSES - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Total Loans	$ 16,143,801	$ 15,874,258
Loans 90 Days or More Past Due and Still Accruing	6,583	12,648
Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	179,613	148,707
Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	72,455	54,024
Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	18,613	14,215
Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	88,545	80,468
Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	15,964,188	15,725,551
Commercial, financial and agricultural
Financing Receivable, Past Due [Line Items]
Total Loans	1,836,663	1,875,993
Loans 90 Days or More Past Due and Still Accruing	1,153	1,165
Commercial, financial and agricultural | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	18,630	17,453
Commercial, financial and agricultural | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,422	3,431
Commercial, financial and agricultural | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	1,708	2,005
Commercial, financial and agricultural | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	11,500	12,017
Commercial, financial and agricultural | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	1,818,033	1,858,540
Consumer installment
Financing Receivable, Past Due [Line Items]
Total Loans	173,642	191,298
Loans 90 Days or More Past Due and Still Accruing	412	584
Consumer installment | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	2,901	3,548
Consumer installment | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	1,555	1,786
Consumer installment | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	555	871
Consumer installment | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	791	891
Consumer installment | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	170,741	187,750
Indirect automobile
Financing Receivable, Past Due [Line Items]
Total Loans	214,120	265,779
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	1,101	1,430
Indirect automobile | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	502	772
Indirect automobile | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	137	185
Indirect automobile | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	462	473
Indirect automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	213,019	264,349
Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Total Loans	732,375	787,837
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	732,375	787,837
Municipal
Financing Receivable, Past Due [Line Items]
Total Loans	547,926	572,701
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	547,926	572,701
Premium finance
Financing Receivable, Past Due [Line Items]
Total Loans	819,163	798,409
Loans 90 Days or More Past Due and Still Accruing	4,727	9,134
Premium finance | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	15,220	20,466
Premium finance | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,872	6,992
Premium finance | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	4,620	4,340
Premium finance | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	4,728	9,134
Premium finance | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	803,943	777,943
Real estate – construction and development
Financing Receivable, Past Due [Line Items]
Total Loans	1,577,215	1,452,339
Loans 90 Days or More Past Due and Still Accruing	287	1,758
Real estate – construction and development | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	28,169	20,189
Real estate – construction and development | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	26,729	16,601
Real estate – construction and development | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	468	1,398
Real estate – construction and development | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	972	2,190
Real estate – construction and development | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	1,549,046	1,432,150
Real estate – commercial and farmland
Financing Receivable, Past Due [Line Items]
Total Loans	6,924,475	6,834,917
Loans 90 Days or More Past Due and Still Accruing	4	7
Real estate – commercial and farmland | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	12,235	13,787
Real estate – commercial and farmland | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,772	6,713
Real estate – commercial and farmland | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	3,080	1,150
Real estate – commercial and farmland | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	3,383	5,924
Real estate – commercial and farmland | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	6,912,240	6,821,130
Real estate – residential
Financing Receivable, Past Due [Line Items]
Total Loans	3,318,222	3,094,985
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	101,357	71,834
Real estate – residential | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	26,603	17,729
Real estate – residential | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	8,045	4,266
Real estate – residential | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	66,709	49,839
Real estate – residential | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	$ 3,216,865	$ 3,023,151