LOANS AND ALLOWANCE FOR LOAN LOSSES - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 12,818,476	$ 8,511,914
Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	102,987	53,984
Current Loans	7,427,000	5,606,473
Total Loans	7,529,987	5,660,457
Loans 90 Days or More Past Due and Still Accruing	5,733	4,222
Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	78,860	35,599
Current Loans	4,996,421	2,553,233
Total Loans	5,075,281	2,588,832
Loans 90 Days or More Past Due and Still Accruing	21	0
Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	54,905	23,089
Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	33,386	16,193
Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	18,256	12,104
Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	12,977	4,166
Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	29,826	18,791
Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	32,497	15,240
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	33,415	16,537
Current Loans	1,613,023	1,299,822
Total Loans	1,646,438	1,316,359
Loans 90 Days or More Past Due and Still Accruing	4,811	3,808
Commercial, financial and agricultural | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6,173	1,852
Current Loans	378,100	370,834
Total Loans	384,273	372,686
Loans 90 Days or More Past Due and Still Accruing	0	0
Commercial, financial and agricultural | Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	16,323	6,479
Commercial, financial and agricultural | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,087	421
Commercial, financial and agricultural | Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	9,925	5,295
Commercial, financial and agricultural | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	348	416
Commercial, financial and agricultural | Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	7,167	4,763
Commercial, financial and agricultural | Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4,738	1,015
Real estate – construction and development | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	8,270	2,424
Current Loans	1,075,294	668,774
Total Loans	1,083,564	671,198
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – construction and development | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,321	6,270
Current Loans	463,176	221,630
Total Loans	465,497	227,900
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – construction and development | Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6,054	1,218
Real estate – construction and development | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,731	627
Real estate – construction and development | Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,222	481
Real estate – construction and development | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2	370
Real estate – construction and development | Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	994	725
Real estate – construction and development | Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	588	5,273
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	7,847	5,800
Current Loans	2,439,987	1,808,729
Total Loans	2,447,834	1,814,529
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – commercial and farmland | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	18,560	4,369
Current Loans	1,886,645	1,333,490
Total Loans	1,905,205	1,337,859
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – commercial and farmland | Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4,195	1,625
Real estate – commercial and farmland | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,209	1,935
Real estate – commercial and farmland | Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	565	530
Real estate – commercial and farmland | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,840	736
Real estate – commercial and farmland | Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,087	3,645
Real estate – commercial and farmland | Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	12,511	1,698
Real estate – residential | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	48,142	24,977
Current Loans	1,853,210	1,378,023
Total Loans	1,901,352	1,403,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – residential | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	42,286	21,943
Current Loans	1,177,985	601,256
Total Loans	1,220,271	623,199
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – residential | Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	25,581	11,423
Real estate – residential | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	20,645	12,531
Real estate – residential | Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,243	4,631
Real estate – residential | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	8,685	2,407
Real estate – residential | Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	17,318	8,923
Real estate – residential | Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	12,956	7,005
Consumer installment | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,313	4,246
Current Loans	445,486	451,125
Total Loans	450,799	455,371
Loans 90 Days or More Past Due and Still Accruing	922	414
Consumer installment | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	9,520	1,165
Current Loans	1,090,515	26,023
Total Loans	1,100,035	27,188
Loans 90 Days or More Past Due and Still Accruing	21	0
Consumer installment | Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,752	2,344
Consumer installment | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6,714	679
Consumer installment | Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,301	1,167
Consumer installment | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,102	237
Consumer installment | Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,260	735
Consumer installment | Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	$ 1,704	$ 249