LOANS AND ALLOWANCE FOR CREDIT LOSSES - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Total Loans	$ 19,997,871	$ 19,855,253
Loans 90 Days or More Past Due and Still Accruing	15,792	17,865
Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	247,959	273,465
Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	69,953	95,203
Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	29,366	34,637
Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	148,640	143,625
Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	19,749,912	19,581,788
Commercial, financial and agricultural
Financing Receivable, Past Due [Line Items]
Total Loans	2,722,180	2,679,403
Loans 90 Days or More Past Due and Still Accruing	3,969	3,267
Commercial, financial and agricultural | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	30,990	33,302
Commercial, financial and agricultural | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	12,302	16,219
Commercial, financial and agricultural | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,307	5,451
Commercial, financial and agricultural | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	13,381	11,632
Commercial, financial and agricultural | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	2,691,190	2,646,101
Consumer
Financing Receivable, Past Due [Line Items]
Total Loans	349,775	384,037
Loans 90 Days or More Past Due and Still Accruing	409	472
Consumer | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	8,781	6,443
Consumer | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,314	2,539
Consumer | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	2,835	3,163
Consumer | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	632	741
Consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	340,994	377,594
Indirect automobile
Financing Receivable, Past Due [Line Items]
Total Loans	83,466	108,648
Loans 90 Days or More Past Due and Still Accruing		0
Indirect automobile | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	469	810
Indirect automobile | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	190	466
Indirect automobile | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	122	77
Indirect automobile | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	157	267
Indirect automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	82,997	107,838
Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Total Loans	958,418	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	958,418	1,038,924
Municipal
Financing Receivable, Past Due [Line Items]
Total Loans	505,515	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	505,515	509,151
Premium finance
Financing Receivable, Past Due [Line Items]
Total Loans	947,257	1,023,479
Loans 90 Days or More Past Due and Still Accruing	11,414	13,626
Premium finance | Total Loans Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	27,438	38,105
Premium finance | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	9,922	13,859
Premium finance | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	6,102	10,620
Premium finance | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	11,414	13,626
Premium finance | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	919,819	985,374
Real estate – construction and development
Financing Receivable, Past Due [Line Items]
Total Loans	2,144,605	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	2,190	30,162
Real estate – construction and development | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	1,727	25,367
Real estate – construction and development | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	0	3,829
Real estate – construction and development | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	463	966
Real estate – construction and development | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	2,142,415	2,056,276
Real estate – commercial and farmland
Financing Receivable, Past Due [Line Items]
Total Loans	7,721,732	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	23,411	12,129
Real estate – commercial and farmland | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	6,723	1,738
Real estate – commercial and farmland | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	5,801	168
Real estate – commercial and farmland | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	10,887	10,223
Real estate – commercial and farmland | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	7,698,321	7,592,738
Real estate – residential
Financing Receivable, Past Due [Line Items]
Total Loans	4,564,923	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	154,680	152,514
Real estate – residential | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	33,775	35,015
Real estate – residential | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	9,199	11,329
Real estate – residential | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans	111,706	106,170
Real estate – residential | Current Loans
Financing Receivable, Past Due [Line Items]
Total Loans	$ 4,410,243	$ 4,267,792