LOANS - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 8,482,339	$ 8,511,914
Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	50,966	53,984
Current Loans	5,705,392	5,606,473
Total Loans	5,756,358	5,660,457
Loans 90 Days or More Past Due and Still Accruing	3,676	4,222
Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	24,157	23,089
Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	8,807	12,104
Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	18,002	18,791
Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	32,616	35,599
Current Loans	2,439,655	2,553,233
Total Loans	2,472,271	2,588,832
Loans 90 Days or More Past Due and Still Accruing	0	0
Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	15,886	16,193
Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,059	4,166
Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	14,671	15,240
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	12,276	16,537
Current Loans	1,370,631	1,299,822
Total Loans	1,382,907	1,316,359
Loans 90 Days or More Past Due and Still Accruing	3,416	3,808
Commercial, financial and agricultural | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,270	6,479
Commercial, financial and agricultural | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,784	5,295
Commercial, financial and agricultural | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4,222	4,763
Commercial, financial and agricultural | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4,805	1,852
Current Loans	323,167	370,834
Total Loans	327,972	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, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,551	421
Commercial, financial and agricultural | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	45	416
Commercial, financial and agricultural | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,209	1,015
Real estate – construction and development | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,180	2,424
Current Loans	674,383	668,774
Total Loans	676,563	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, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	957	1,218
Real estate – construction and development | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	531	481
Real estate – construction and development | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	692	725
Real estate – construction and development | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6,585	6,270
Current Loans	232,828	221,630
Total Loans	239,413	227,900
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – construction and development | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,112	627
Real estate – construction and development | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, 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, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,473	5,273
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	8,712	5,800
Current Loans	1,886,225	1,808,729
Total Loans	1,894,937	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, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,784	1,625
Real estate – commercial and farmland | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,276	530
Real estate – commercial and farmland | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,652	3,645
Real estate – commercial and farmland | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,576	4,369
Current Loans	1,274,939	1,333,490
Total Loans	1,280,515	1,337,859
Loans 90 Days or More Past Due and Still Accruing	0	0
Real estate – commercial and farmland | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,003	1,935
Real estate – commercial and farmland | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	170	736
Real estate – commercial and farmland | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,403	1,698
Real estate – residential | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	24,576	24,977
Current Loans	1,340,906	1,378,023
Total Loans	1,365,482	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, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	13,394	11,423
Real estate – residential | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,287	4,631
Real estate – residential | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	9,895	8,923
Real estate – residential | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	14,552	21,943
Current Loans	583,183	601,256
Total Loans	597,735	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, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	7,488	12,531
Real estate – residential | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,747	2,407
Real estate – residential | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,317	7,005
Consumer installment | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,222	4,246
Current Loans	433,247	451,125
Total Loans	436,469	455,371
Loans 90 Days or More Past Due and Still Accruing	260	414
Consumer installment | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,752	2,344
Consumer installment | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	929	1,167
Consumer installment | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	541	735
Consumer installment | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,098	1,165
Current Loans	25,538	26,023
Total Loans	26,636	27,188
Loans 90 Days or More Past Due and Still Accruing	0	0
Consumer installment | Purchased Loans | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	732	679
Consumer installment | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	97	237
Consumer installment | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	$ 269	$ 249