LOANS - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 6,190,171	$ 6,046,355
Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	51,121	44,215
Current Loans	5,000,865	4,812,299
Total Loans	5,051,986	4,856,514
Loans 90 Days or More Past Due and Still Accruing	2,497	5,991
Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	28,412	20,131
Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	10,205	7,508
Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	12,504	16,576
Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	18,538	14,774
Current Loans	800,049	846,821
Total Loans	818,587	861,595
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	6,413	4,056
Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,644	2,354
Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	10,481	8,364
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	19,261	18,387
Current Loans	1,368,176	1,344,121
Total Loans	1,387,437	1,362,508
Loans 90 Days or More Past Due and Still Accruing	2,383	5,991
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	10,081	8,124
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	5,750	3,285
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	3,430	6,978
Commercial, financial and agricultural | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	881	793
Current Loans	63,731	73,585
Total Loans	64,612	74,378
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	103	0
Commercial, financial and agricultural | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	0	33
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	778	760
Real estate – construction and development | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,536	1,121
Current Loans	629,968	623,474
Total Loans	631,504	624,595
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	1,202	810
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	168	23
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	166	288
Real estate – construction and development | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,065	2,635
Current Loans	45,875	62,878
Total Loans	48,940	65,513
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	473	87
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	31	31
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	2,561	2,517
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6,067	3,596
Current Loans	1,630,587	1,531,843
Total Loans	1,636,654	1,535,439
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	4,189	869
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	590	787
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	1,288	1,940
Real estate – commercial and farmland | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4,126	4,615
Current Loans	461,744	463,631
Total Loans	465,870	468,246
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	1,589	1,190
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	1,022	701
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	1,515	2,724
Real estate – residential | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	22,172	18,754
Current Loans	1,057,856	990,707
Total Loans	1,080,028	1,009,461
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	11,907	8,772
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	3,058	2,941
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	7,207	7,041
Real estate – residential | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	10,413	6,627
Current Loans	226,040	243,912
Total Loans	236,453	250,539
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	4,228	2,722
Real estate – residential | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	591	1,585
Real estate – residential | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,594	2,320
Consumer installment | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,085	2,357
Current Loans	314,278	322,154
Total Loans	316,363	324,511
Loans 90 Days or More Past Due and Still Accruing	114	0
Consumer installment | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,033	1,556
Consumer installment | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	639	472
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	413	329
Consumer installment | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	53	104
Current Loans	2,659	2,815
Total Loans	2,712	2,919
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	20	57
Consumer installment | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	0	4
Consumer installment | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	$ 33	$ 43