LOANS - Loans by Risk Grade (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 8,490,534	$ 6,046,355
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,380,515	4,856,514
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,812,510	861,595
1 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	545,902	554,979
1 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	55,183	3,964
2 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	660,495	688,481
2 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	139,683	101,098
3 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,211,703	2,033,979
3 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	449,317	259,872
4 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,820,884	1,487,781
4 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,908,143	385,080
5 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	52,069	16,996
5 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	135,281	19,736
6 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	38,150	30,075
6 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	45,095	37,121
7 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	51,305	44,216
7 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	79,808	54,724
8 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7	7
8 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
9 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
9 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,446,857	1,362,508
Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	397,517	74,378
Commercial, financial and agricultural | 1 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	530,629	539,899
Commercial, financial and agricultural | 1 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	54,608	3,358
Commercial, financial and agricultural | 2 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	562,728	568,557
Commercial, financial and agricultural | 2 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	36,766	4,541
Commercial, financial and agricultural | 3 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	168,418	125,740
Commercial, financial and agricultural | 3 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	54,774	8,517
Commercial, financial and agricultural | 4 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	141,404	117,358
Commercial, financial and agricultural | 4 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	193,836	43,085
Commercial, financial and agricultural | 5 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	22,144	330
Commercial, financial and agricultural | 5 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	39,040	0
Commercial, financial and agricultural | 6 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	6,189	5,236
Commercial, financial and agricultural | 6 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	14,246	13,718
Commercial, financial and agricultural | 7 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	15,338	5,381
Commercial, financial and agricultural | 7 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,247	1,159
Commercial, financial and agricultural | 8 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7	7
Commercial, financial and agricultural | 8 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Commercial, financial and agricultural | 9 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Commercial, financial and agricultural | 9 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	672,155	624,595
Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	268,443	65,513
Real estate – construction and development | 1 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – construction and development | 1 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – construction and development | 2 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	931	1,005
Real estate – construction and development | 2 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – construction and development | 3 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	57,107	59,318
Real estate – construction and development | 3 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	21,334	13,014
Real estate – construction and development | 4 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	601,601	552,918
Real estate – construction and development | 4 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	224,596	39,877
Real estate – construction and development | 5 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,265	4,474
Real estate – construction and development | 5 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,990	2,306
Real estate – construction and development | 6 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,381	4,207
Real estate – construction and development | 6 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,261	4,076
Real estate – construction and development | 7 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,870	2,673
Real estate – construction and development | 7 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	11,262	6,240
Real estate – construction and development | 8 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – construction and development | 8 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – construction and development | 9 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – construction and development | 9 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,640,411	1,535,439
Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,428,490	468,246
Real estate – commercial and farmland | 1 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,231	5,790
Real estate – commercial and farmland | 1 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – commercial and farmland | 2 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	51,713	68,507
Real estate – commercial and farmland | 2 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,494	5,047
Real estate – commercial and farmland | 3 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	885,659	966,391
Real estate – commercial and farmland | 3 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	302,001	186,187
Real estate – commercial and farmland | 4 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	642,917	454,506
Real estate – commercial and farmland | 4 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	993,807	230,570
Real estate – commercial and farmland | 5 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	16,819	6,408
Real estate – commercial and farmland | 5 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	69,624	6,081
Real estate – commercial and farmland | 6 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	22,530	15,108
Real estate – commercial and farmland | 6 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	18,401	13,637
Real estate – commercial and farmland | 7 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	15,542	18,729
Real estate – commercial and farmland | 7 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	37,163	26,724
Real estate – commercial and farmland | 8 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – commercial and farmland | 8 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – commercial and farmland | 9 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – commercial and farmland | 9 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,245,370	1,009,461
Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	679,205	250,539
Real estate – residential | 1 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	17	47
Real estate – residential | 1 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – residential | 2 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	45,015	49,742
Real estate – residential | 2 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	95,222	91,270
Real estate – residential | 3 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,076,090	843,178
Real estate – residential | 3 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	69,889	50,988
Real estate – residential | 4 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	94,518	88,537
Real estate – residential | 4 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	459,944	70,837
Real estate – residential | 5 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,840	5,781
Real estate – residential | 5 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	20,627	11,349
Real estate – residential | 6 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,936	5,339
Real estate – residential | 6 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,132	5,637
Real estate – residential | 7 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	16,954	16,837
Real estate – residential | 7 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	26,391	20,458
Real estate – residential | 8 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – residential | 8 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – residential | 9 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Real estate – residential | 9 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	375,722	324,511
Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	38,855	2,919
Consumer installment | 1 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	10,025	9,243
Consumer installment | 1 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	575	606
Consumer installment | 2 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	108	670
Consumer installment | 2 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	201	240
Consumer installment | 3 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	24,429	39,352
Consumer installment | 3 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,319	1,166
Consumer installment | 4 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	340,444	274,462
Consumer installment | 4 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	35,960	711
Consumer installment | 5 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1	3
Consumer installment | 5 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Consumer installment | 6 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	114	185
Consumer installment | 6 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	55	53
Consumer installment | 7 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	601	596
Consumer installment | 7 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	745	143
Consumer installment | 8 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Consumer installment | 8 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Consumer installment | 9 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Consumer installment | 9 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 0	$ 0