LOANS AND ALLOWANCE FOR LOAN LOSSES - Loans by Risk Grade (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 12,818,476	$ 8,511,914
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,529,987	5,660,457
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,075,281	2,588,832
10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	509,984	542,164
10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	77,893	90,775
15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	746,591	523,101
15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	93,781	84,617
20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,289,885	2,408,128
20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,532,115	656,289
23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	119,019	59,054
23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	114,001	63,613
25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,772,794	2,047,688
25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,111,747	1,586,377
30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	32,666	35,118
30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	53,746	30,448
40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	59,038	45,204
40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	91,998	76,713
50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8	0
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	2	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	1,646,438	1,316,359
Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	384,273	372,686
Commercial, financial and agricultural | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	497,942	530,864
Commercial, financial and agricultural | 10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	76,516	90,205
Commercial, financial and agricultural | 15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	670,267	452,250
Commercial, financial and agricultural | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,729	2,648
Commercial, financial and agricultural | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	161,353	174,811
Commercial, financial and agricultural | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	72,008	20,489
Commercial, financial and agricultural | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	19,450	13,714
Commercial, financial and agricultural | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	13,867	14,445
Commercial, financial and agricultural | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	289,882	137,038
Commercial, financial and agricultural | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	192,890	215,096
Commercial, financial and agricultural | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,952	5,130
Commercial, financial and agricultural | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,950	11,601
Commercial, financial and agricultural | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,592	2,552
Commercial, financial and agricultural | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,313	18,202
Commercial, financial and agricultural | 50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
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	1,083,564	671,198
Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	465,497	227,900
Real estate – construction and development | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	40
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	17,535	681
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	76,871	74,657
Real estate – construction and development | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	13,252	18,022
Real estate – construction and development | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	24,415	6,264
Real estate – construction and development | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	17,343	2,728
Real estate – construction and development | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	954,555	582,456
Real estate – construction and development | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	423,119	195,079
Real estate – construction and development | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,786	4,091
Real estate – construction and development | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,437	1,459
Real estate – construction and development | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,402	3,009
Real estate – construction and development | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,346	10,612
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	2,447,834	1,814,529
Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,905,205	1,337,859
Real estate – commercial and farmland | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	208	500
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	26,688	37,079
Real estate – commercial and farmland | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8,611	7,407
Real estate – commercial and farmland | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,313,853	888,433
Real estate – commercial and farmland | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	406,185	230,089
Real estate – commercial and farmland | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	67,047	30,364
Real estate – commercial and farmland | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	66,072	29,468
Real estate – commercial and farmland | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	993,053	814,068
Real estate – commercial and farmland | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,355,031	1,034,943
Real estate – commercial and farmland | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,268	20,959
Real estate – commercial and farmland | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	33,674	10,063
Real estate – commercial and farmland | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	26,717	23,126
Real estate – commercial and farmland | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	35,632	25,889
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	1,901,352	1,403,000
Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,220,271	623,199
Real estate – residential | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	27	16
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	32,101	33,043
Real estate – residential | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	60,154	74,398
Real estate – residential | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,730,257	1,246,383
Real estate – residential | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	990,302	385,279
Real estate – residential | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8,077	8,634
Real estate – residential | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	16,541	16,937
Real estate – residential | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	104,597	94,143
Real estate – residential | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	118,181	118,082
Real estate – residential | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,540	4,881
Real estate – residential | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,592	7,231
Real estate – residential | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	23,753	15,900
Real estate – residential | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	27,501	21,272
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	450,799	455,371
Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,100,035	27,188
Consumer installment | 10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	11,807	10,744
Consumer installment | 10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,377	570
Consumer installment | 15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	48
Consumer installment | 15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	19,287	164
Consumer installment | 20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,551	23,844
Consumer installment | 20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,050,368	2,410
Consumer installment | 23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	30	78
Consumer installment | 23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	178	35
Consumer installment | 25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	430,707	419,983
Consumer installment | 25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	22,526	23,177
Consumer installment | 30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	120	57
Consumer installment | 30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	93	94
Consumer installment | 40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	574	617
Consumer installment | 40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	6,206	738
Consumer installment | 50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8	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	2	0
Consumer installment | 60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 0	$ 0