LOANS - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Total Loans	$ 12,826,284	$ 8,511,914
Loans Excluding Purchased Loan
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	63,454	53,984
Current Loans	7,145,362	5,606,473
Total Loans	7,208,816	5,660,457
Loans 90 Days or More Past Due and Still Accruing	5,836	4,222
Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	30,860	23,089
Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	7,697	12,104
Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	24,897	18,791
Purchased Loans
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	87,558	35,599
Current Loans	5,300,778	2,553,233
Total Loans	5,388,336	2,588,832
Loans 90 Days or More Past Due and Still Accruing	489	0
Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	30,560	16,193
Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	10,913	4,166
Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	46,085	15,240
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	21,219	16,537
Current Loans	1,760,018	1,299,822
Total Loans	1,781,237	1,316,359
Loans 90 Days or More Past Due and Still Accruing	5,380	3,808
Commercial, financial and agricultural | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	10,695	6,479
Commercial, financial and agricultural | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	2,246	5,295
Commercial, financial and agricultural | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	8,278	4,763
Commercial, financial and agricultural | Purchased Loans
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	5,913	1,852
Current Loans	379,442	370,834
Total Loans	385,355	372,686
Loans 90 Days or More Past Due and Still Accruing	0	0
Commercial, financial and agricultural | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	758	421
Commercial, financial and agricultural | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	1,435	416
Commercial, financial and agricultural | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	3,720	1,015
Real estate – construction and development | Loans Excluding Purchased Loan
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	2,574	2,424
Current Loans	944,797	668,774
Total Loans	947,371	671,198
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – construction and development | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	999	1,218
Real estate – construction and development | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	675	481
Real estate – construction and development | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	900	725
Real estate – construction and development | Purchased Loans
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	5,543	6,270
Current Loans	515,781	221,630
Total Loans	521,324	227,900
Loans 90 Days or More Past Due and Still Accruing	414	0
Real estate – construction and development | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	332	627
Real estate – construction and development | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	0	370
Real estate – construction and development | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	5,211	5,273
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	7,240	5,800
Current Loans	2,145,288	1,808,729
Total Loans	2,152,528	1,814,529
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – commercial and farmland | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	4,101	1,625
Real estate – commercial and farmland | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	326	530
Real estate – commercial and farmland | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	2,813	3,645
Real estate – commercial and farmland | Purchased Loans
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	17,394	4,369
Current Loans	2,039,990	1,333,490
Total Loans	2,057,384	1,337,859
Loans 90 Days or More Past Due and Still Accruing	66	0
Real estate – commercial and farmland | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	2,416	1,935
Real estate – commercial and farmland | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	1,480	736
Real estate – commercial and farmland | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	13,498	1,698
Real estate – residential | Loans Excluding Purchased Loan
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	28,272	24,977
Current Loans	1,837,856	1,378,023
Total Loans	1,866,128	1,403,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – residential | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	12,898	11,423
Real estate – residential | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	3,235	4,631
Real estate – residential | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	12,139	8,923
Real estate – residential | Purchased Loans
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	55,252	21,943
Current Loans	1,229,844	601,256
Total Loans	1,285,096	623,199
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – residential | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	24,707	12,531
Real estate – residential | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	7,092	2,407
Real estate – residential | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	23,453	7,005
Consumer installment | Loans Excluding Purchased Loan
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	4,149	4,246
Current Loans	457,403	451,125
Total Loans	461,552	455,371
Loans 90 Days or More Past Due and Still Accruing	456	414
Consumer installment | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	2,167	2,344
Consumer installment | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	1,215	1,167
Consumer installment | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	767	735
Consumer installment | Purchased Loans
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	3,456	1,165
Current Loans	1,135,721	26,023
Total Loans	1,139,177	27,188
Loans 90 Days or More Past Due and Still Accruing	9	0
Consumer installment | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	2,347	679
Consumer installment | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	906	237
Consumer installment | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Past Due	$ 203	$ 249