LOANS - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 8,490,534	$ 6,046,355
Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	47,069	44,215
Current Loans	5,333,446	4,812,299
Total Loans	5,380,515	4,856,514
Loans 90 Days or More Past Due and Still Accruing	7,421	5,991
Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	13,757	20,131
Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	12,400	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	20,912	16,576
Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	37,742	14,774
Current Loans	2,774,768	846,821
Total Loans	2,812,510	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	14,962	4,056
Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,288	2,354
Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	19,492	8,364
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	19,732	18,387
Current Loans	1,427,125	1,344,121
Total Loans	1,446,857	1,362,508
Loans 90 Days or More Past Due and Still Accruing	7,279	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	4,981	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	6,251	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	8,500	6,978
Commercial, financial and agricultural | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,593	793
Current Loans	395,924	73,585
Total Loans	397,517	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	371	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	65	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	1,157	760
Real estate – construction and development | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,550	1,121
Current Loans	670,605	623,474
Total Loans	672,155	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	757	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	434	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	359	288
Real estate – construction and development | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	9,136	2,635
Current Loans	259,307	62,878
Total Loans	268,443	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	1,155	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	469	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	7,512	2,517
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6,172	3,596
Current Loans	1,634,239	1,531,843
Total Loans	1,640,411	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	1,914	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	596	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	3,662	1,940
Real estate – commercial and farmland | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4,838	4,615
Current Loans	1,423,652	463,631
Total Loans	1,428,490	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	2,736	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	88	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	2,014	2,724
Real estate – residential | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	17,035	18,754
Current Loans	1,228,335	990,707
Total Loans	1,245,370	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	4,669	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	4,457	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	7,909	7,041
Real estate – residential | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	20,931	6,627
Current Loans	658,274	243,912
Total Loans	679,205	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	9,609	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	2,640	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	8,682	2,320
Consumer installment | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,580	2,357
Current Loans	373,142	322,154
Total Loans	375,722	324,511
Loans 90 Days or More Past Due and Still Accruing	142	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	1,436	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	662	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	482	329
Consumer installment | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,244	104
Current Loans	37,611	2,815
Total Loans	38,855	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	1,091	57
Consumer installment | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	26	4
Consumer installment | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	$ 127	$ 43