LOANS AND ALLOWANCE FOR CREDIT LOSSES - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Total Loans	$ 20,201,079	$ 19,855,253
Loans 90 Days or More Past Due and Still Accruing	11,891	17,865
Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	236,635	273,465
Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	70,506	95,203
Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	35,967	34,637
Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	130,162	143,625
Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	19,964,444	19,581,788
Commercial, financial and agricultural
Financing Receivable, Past Due [Line Items]
Total Loans	2,632,836	2,679,403
Loans 90 Days or More Past Due and Still Accruing	4,765	3,267
Commercial, financial and agricultural | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	25,276	33,302
Commercial, financial and agricultural | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	12,774	16,219
Commercial, financial and agricultural | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,438	5,451
Commercial, financial and agricultural | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	7,064	11,632
Commercial, financial and agricultural | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	2,607,560	2,646,101
Consumer
Financing Receivable, Past Due [Line Items]
Total Loans	259,797	384,037
Loans 90 Days or More Past Due and Still Accruing	0	472
Consumer | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	3,719	6,443
Consumer | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	2,290	2,539
Consumer | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	804	3,163
Consumer | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	625	741
Consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	256,078	377,594
Indirect automobile
Financing Receivable, Past Due [Line Items]
Total Loans	47,108	108,648
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	269	810
Indirect automobile | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	131	466
Indirect automobile | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	41	77
Indirect automobile | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	97	267
Indirect automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	46,839	107,838
Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Total Loans	852,823	1,038,924
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	852,823	1,038,924
Municipal
Financing Receivable, Past Due [Line Items]
Total Loans	497,093	509,151
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	497,093	509,151
Premium finance
Financing Receivable, Past Due [Line Items]
Total Loans	1,007,334	1,023,479
Loans 90 Days or More Past Due and Still Accruing	7,126	13,626
Premium finance | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	22,034	38,105
Premium finance | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	9,648	13,859
Premium finance | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,260	10,620
Premium finance | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	7,126	13,626
Premium finance | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	985,300	985,374
Real estate – construction and development
Financing Receivable, Past Due [Line Items]
Total Loans	2,236,686	2,086,438
Loans 90 Days or More Past Due and Still Accruing	0	500
Real estate – construction and development | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	1,542	30,162
Real estate – construction and development | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	892	25,367
Real estate – construction and development | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	370	3,829
Real estate – construction and development | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	280	966
Real estate – construction and development | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	2,235,144	2,056,276
Real estate – commercial and farmland
Financing Receivable, Past Due [Line Items]
Total Loans	7,865,389	7,604,867
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	13,417	12,129
Real estate – commercial and farmland | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,358	1,738
Real estate – commercial and farmland | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	7,128	168
Real estate – commercial and farmland | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	931	10,223
Real estate – commercial and farmland | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	7,851,972	7,592,738
Real estate – residential
Financing Receivable, Past Due [Line Items]
Total Loans	4,802,013	4,420,306
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	170,378	152,514
Real estate – residential | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	39,413	35,015
Real estate – residential | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	16,926	11,329
Real estate – residential | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	114,039	106,170
Real estate – residential | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	$ 4,631,635	$ 4,267,792