LOANS - Analysis of Past-Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 5,957,022	$ 5,264,326
Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	33,656	32,893
Current Loans	4,541,022	3,593,928
Total Loans	4,574,678	3,626,821
Loans 90 Days or More Past Due and Still Accruing	2,941	0
Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	12,425	14,780
Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	5,983	3,784
Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	15,248	14,329
Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	20,047	25,060
Current Loans	897,079	1,044,131
Total Loans	917,126	1,069,191
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	10,046	6,896
Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	2,699	1,053
Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	7,302	17,111
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	12,901	1,940
Current Loans	1,294,308	965,198
Total Loans	1,307,209	967,138
Loans 90 Days or More Past Due and Still Accruing	2,941	0
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	5,388	565
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	2,488	82
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	5,025	1,293
Commercial, financial and agricultural | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	2,964	724
Current Loans	77,931	95,813
Total Loans	80,895	96,537
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	2,674	113
Commercial, financial and agricultural | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	2	18
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	288	593
Real estate – construction and development | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	910	1,793
Current Loans	549,279	361,252
Total Loans	550,189	363,045
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	341	908
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	52	446
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	517	439
Real estate – construction and development | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	3,869	2,690
Current Loans	64,714	78,678
Total Loans	68,583	81,368
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	1,221	161
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	935	11
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	1,713	2,518
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	8,669	14,985
Current Loans	1,550,213	1,391,234
Total Loans	1,558,882	1,406,219
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	2,369	6,329
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	1,097	1,711
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	5,203	6,945
Real estate – commercial and farmland | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	5,983	9,512
Current Loans	494,186	566,843
Total Loans	500,169	576,355
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	2,842	2,034
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	1,318	326
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	1,823	7,152
Real estate – residential | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	9,396	12,938
Current Loans	959,893	768,080
Total Loans	969,289	781,018
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	3,293	6,354
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	1,938	1,282
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	4,165	5,302
Real estate – residential | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	7,183	12,099
Current Loans	257,129	298,178
Total Loans	264,312	310,277
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	3,308	4,566
Real estate – residential | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	440	698
Real estate – residential | Purchased Loans | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	3,435	6,835
Consumer installment | Loans Excluding Purchased Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	1,780	1,237
Current Loans	181,534	95,678
Total Loans	183,314	96,915
Loans 90 Days or More Past Due and Still Accruing	0	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	1,034	624
Consumer installment | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	408	263
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	338	350
Consumer installment | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	48	35
Current Loans	3,119	4,619
Total Loans	3,167	4,654
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	22
Consumer installment | Purchased Loans | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	4	0
Consumer installment | Purchased Loans | Loans 90 or More Days Past Due
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	5,795	12,486
Total Loans	5,795	12,486
Loans 90 Days or More Past Due and Still Accruing	0	0
Other | Loans Excluding Purchased Loan | Loans 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	0	0
Other | Loans Excluding Purchased Loan | Loans 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	0	0
Other | Loans Excluding Purchased Loan | Loans 90 or More Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans past due	0	0
Other | Purchased Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 0	$ 0