LOANS AND ALLOWANCE FOR CREDIT LOSSES - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	$ 15,874,258	$ 14,480,925	$ 12,818,476
Loans 90 Days or More Past Due and Still Accruing	12,648	8,326
Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	148,707	134,659
Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	54,024	56,483
Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	14,215	13,582
Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	80,468	64,594
Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	15,725,551	14,346,266
Commercial, financial and agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,875,993	1,627,477	802,171
Loans 90 Days or More Past Due and Still Accruing	1,165	0
Commercial, financial and agricultural | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	17,453	12,246
Commercial, financial and agricultural | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	3,431	4,576
Commercial, financial and agricultural | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	2,005	2,018
Commercial, financial and agricultural | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	12,017	5,652
Commercial, financial and agricultural | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,858,540	1,615,231
Consumer installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	191,298	306,995	498,577
Loans 90 Days or More Past Due and Still Accruing	584	1,755
Consumer installment | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	3,548	5,621
Consumer installment | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,786	2,189
Consumer installment | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	871	1,114
Consumer installment | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	891	2,318
Consumer installment | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	187,750	301,374
Indirect automobile
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	265,779	580,083	1,061,824
Loans 90 Days or More Past Due and Still Accruing	0	0
Indirect automobile | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,430	6,470
Indirect automobile | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	772	3,293
Indirect automobile | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	185	1,006
Indirect automobile | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	473	2,171
Indirect automobile | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	264,349	573,613
Mortgage warehouse
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	787,837	916,353	526,369
Loans 90 Days or More Past Due and Still Accruing	0	0
Mortgage warehouse | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Mortgage warehouse | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Mortgage warehouse | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Mortgage warehouse | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Mortgage warehouse | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	787,837	916,353
Municipal
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	572,701	659,403	564,304
Loans 90 Days or More Past Due and Still Accruing	0	0
Municipal | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Municipal | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Municipal | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Municipal | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	0	0
Municipal | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	572,701	659,403
Premium finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	798,409	687,841	654,669
Loans 90 Days or More Past Due and Still Accruing	9,134	6,571
Premium finance | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	20,466	17,654
Premium finance | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	6,992	7,188
Premium finance | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	4,340	3,895
Premium finance | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	9,134	6,571
Premium finance | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	777,943	670,187
Real estate – construction and development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,452,339	1,606,710	1,549,062
Loans 90 Days or More Past Due and Still Accruing	1,758	0
Real estate – construction and development | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	20,189	19,221
Real estate – construction and development | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	16,601	13,348
Real estate – construction and development | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,398	723
Real estate – construction and development | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	2,190	5,150
Real estate – construction and development | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,432,150	1,587,489
Real estate – commercial and farmland
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	6,834,917	5,300,006	4,353,039
Loans 90 Days or More Past Due and Still Accruing	7	0
Real estate – commercial and farmland | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	13,787	15,722
Real estate – commercial and farmland | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	6,713	5,370
Real estate – commercial and farmland | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	1,150	1,701
Real estate – commercial and farmland | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	5,924	8,651
Real estate – commercial and farmland | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	6,821,130	5,284,284
Real estate – residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	3,094,985	2,796,057	$ 2,808,461
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – residential | Total Loans Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	71,834	57,725
Real estate – residential | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	17,729	20,519
Real estate – residential | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	4,266	3,125
Real estate – residential | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	49,839	34,081
Real estate – residential | Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income	$ 3,023,151	$ 2,738,332