LOANS AND ALLOWANCE FOR LOAN LOSSES - Loans by Risk Grade (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 8,511,914	$ 6,046,355
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,660,457	4,856,514
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,588,832	861,595
10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	542,164	554,979
10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	90,775	3,964
15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	523,101	688,481
15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	84,617	101,098
20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,408,128	2,033,979
20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	656,289	259,872
23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	59,054	16,996
23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	63,613	19,736
25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,047,688	1,487,781
25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,586,377	385,080
30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	35,118	30,075
30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	30,448	37,121
40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	45,204	44,216
40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	76,713	54,724
50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	7
50 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
60 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,316,359	1,362,508
Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	372,686	74,378
Commercial, financial and agricultural | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	530,864	539,899
Commercial, financial and agricultural | 10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	90,205	3,358
Commercial, financial and agricultural | 15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	452,250	568,557
Commercial, financial and agricultural | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,648	4,541
Commercial, financial and agricultural | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	174,811	125,740
Commercial, financial and agricultural | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,489	8,517
Commercial, financial and agricultural | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	13,714	330
Commercial, financial and agricultural | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	14,445	0
Commercial, financial and agricultural | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	137,038	117,358
Commercial, financial and agricultural | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	215,096	43,085
Commercial, financial and agricultural | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,130	5,236
Commercial, financial and agricultural | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	11,601	13,718
Commercial, financial and agricultural | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,552	5,381
Commercial, financial and agricultural | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	18,202	1,159
Commercial, financial and agricultural | 50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	7
Commercial, financial and agricultural | 50 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Commercial, financial and agricultural | 60 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Commercial, financial and agricultural | 60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	671,198	624,595
Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	227,900	65,513
Real estate – construction and development | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	40	0
Real estate – construction and development | 10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – construction and development | 15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	681	1,005
Real estate – construction and development | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – construction and development | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	74,657	59,318
Real estate – construction and development | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	18,022	13,014
Real estate – construction and development | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	6,264	4,474
Real estate – construction and development | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,728	2,306
Real estate – construction and development | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	582,456	552,918
Real estate – construction and development | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	195,079	39,877
Real estate – construction and development | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	4,091	4,207
Real estate – construction and development | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,459	4,076
Real estate – construction and development | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,009	2,673
Real estate – construction and development | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,612	6,240
Real estate – construction and development | 50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – construction and development | 50 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – construction and development | 60 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – construction and development | 60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,814,529	1,535,439
Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,337,859	468,246
Real estate – commercial and farmland | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	500	5,790
Real estate – commercial and farmland | 10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – commercial and farmland | 15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	37,079	68,507
Real estate – commercial and farmland | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,407	5,047
Real estate – commercial and farmland | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	888,433	966,391
Real estate – commercial and farmland | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	230,089	186,187
Real estate – commercial and farmland | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	30,364	6,408
Real estate – commercial and farmland | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	29,468	6,081
Real estate – commercial and farmland | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	814,068	454,506
Real estate – commercial and farmland | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,034,943	230,570
Real estate – commercial and farmland | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,959	15,108
Real estate – commercial and farmland | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,063	13,637
Real estate – commercial and farmland | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	23,126	18,729
Real estate – commercial and farmland | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	25,889	26,724
Real estate – commercial and farmland | 50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – commercial and farmland | 50 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – commercial and farmland | 60 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – commercial and farmland | 60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,403,000	1,009,461
Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	623,199	250,539
Real estate – residential | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	16	47
Real estate – residential | 10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – residential | 15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	33,043	49,742
Real estate – residential | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	74,398	91,270
Real estate – residential | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,246,383	843,178
Real estate – residential | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	385,279	50,988
Real estate – residential | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8,634	5,781
Real estate – residential | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	16,937	11,349
Real estate – residential | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	94,143	88,537
Real estate – residential | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	118,082	70,837
Real estate – residential | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	4,881	5,339
Real estate – residential | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,231	5,637
Real estate – residential | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	15,900	16,837
Real estate – residential | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	21,272	20,458
Real estate – residential | 50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – residential | 50 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – residential | 60 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Real estate – residential | 60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	455,371	324,511
Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	27,188	2,919
Consumer installment | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,744	9,243
Consumer installment | 10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	570	606
Consumer installment | 15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	48	670
Consumer installment | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	164	240
Consumer installment | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	23,844	39,352
Consumer installment | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,410	1,166
Consumer installment | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	78	3
Consumer installment | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	35	0
Consumer installment | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	419,983	274,462
Consumer installment | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	23,177	711
Consumer installment | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	57	185
Consumer installment | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	94	53
Consumer installment | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	617	596
Consumer installment | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	738	143
Consumer installment | 50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Consumer installment | 50 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Consumer installment | 60 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Consumer installment | 60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 0	$ 0