LOANS AND ALLOWANCE FOR LOAN LOSSES - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 6,046,355	$ 5,264,326
Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	44,215	32,893
Current Loans	4,812,299	3,593,928
Total Loans	4,856,514	3,626,821
Loans 90 Days or More Past Due and Still Accruing	5,991	0
Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	14,774	25,060
Current Loans	846,821	1,044,131
Total Loans	861,595	1,069,191
Loans 90 Days or More Past Due and Still Accruing	0	0
Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	20,131	14,780
Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4,056	6,896
Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	7,508	3,784
Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,354	1,053
Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	16,576	14,329
Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	8,364	17,111
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	18,387	1,940
Current Loans	1,344,121	965,198
Total Loans	1,362,508	967,138
Loans 90 Days or More Past Due and Still Accruing	5,991	0
Commercial, financial and agricultural | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	793	724
Current Loans	73,585	95,813
Total Loans	74,378	96,537
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	8,124	565
Commercial, financial and agricultural | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	0	113
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	3,285	82
Commercial, financial and agricultural | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	33	18
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	6,978	1,293
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	760	593
Real estate – construction and development | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,121	1,793
Current Loans	623,474	361,252
Total Loans	624,595	363,045
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	2,635	2,690
Current Loans	62,878	78,678
Total Loans	65,513	81,368
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	810	908
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	87	161
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	23	446
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	31	11
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	288	439
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	2,517	2,518
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,596	14,985
Current Loans	1,531,843	1,391,234
Total Loans	1,535,439	1,406,219
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	4,615	9,512
Current Loans	463,631	566,843
Total Loans	468,246	576,355
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	869	6,329
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	1,190	2,034
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	787	1,711
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	701	326
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	1,940	6,945
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	2,724	7,152
Real estate – residential | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	18,754	12,938
Current Loans	990,707	768,080
Total Loans	1,009,461	781,018
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	6,627	12,099
Current Loans	243,912	298,178
Total Loans	250,539	310,277
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	8,772	6,354
Real estate – residential | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,722	4,566
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	2,941	1,282
Real estate – residential | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,585	698
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	7,041	5,302
Real estate – residential | Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,320	6,835
Consumer installment | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,357	1,237
Current Loans	306,837	95,678
Total Loans	309,194	96,915
Loans 90 Days or More Past Due and Still Accruing	0	0
Consumer installment | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	104	35
Current Loans	2,815	4,619
Total Loans	2,919	4,654
Loans 90 Days or More Past Due and Still Accruing	0	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	1,556	624
Consumer installment | Loans 30-59 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	57	22
Consumer installment | Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	472	263
Consumer installment | Loans 60-89 Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	4	0
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	329	350
Consumer installment | Loans 90 or More Days Past Due | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	43	13
Other | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	0	0
Current Loans	15,317	12,486
Total Loans	15,317	12,486
Loans 90 Days or More Past Due and Still Accruing	0	0
Other | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	0	0
Other | Loans 30-59 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	0	0
Other | Loans 60-89 Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	0	0
Other | Loans 90 or More Days Past Due | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	$ 0	$ 0