LOANS - Loans by Risk Grade (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 5,957,022	$ 5,264,326
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	917,126	1,069,191
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,574,678	3,626,821
Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	80,895	96,537
Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,307,209	967,138
Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	68,583	81,368
Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	550,189	363,045
Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	500,169	576,355
Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,558,882	1,406,219
Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	264,312	310,277
Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	969,289	781,018
Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	3,167	4,654
Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	183,314	96,915
Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,795	12,486
10 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,039	6,536
10 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	510,262	414,564
10 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	3,377	5,722
10 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	495,116	397,093
10 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
10 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
10 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
10 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	6,029	8,814
10 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
10 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	49	125
10 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	662	814
10 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	9,068	8,532
10 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
10 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
15 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	107,097	40,786
15 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	692,217	539,147
15 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,969	1,266
15 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	559,781	376,323
15 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
15 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	959	5,390
15 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,327	7,619
15 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	75,462	102,893
15 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	96,570	31,331
15 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	55,759	54,136
15 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	231	570
15 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	256	405
15 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
15 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
20 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	275,855	334,353
20 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,003,173	1,669,998
20 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	9,497	16,204
20 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	117,904	97,057
20 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	13,548	10,686
20 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	48,640	36,307
20 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	198,960	194,168
20 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,005,945	889,539
20 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	52,646	111,712
20 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	800,557	609,583
20 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,204	1,583
20 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	24,332	25,026
20 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
20 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,795	12,486
23 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	19,859	27,475
23 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	14,977	23,186
23 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	22
23 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	343	366
23 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,302	3,643
23 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,403	6,803
23 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	6,936	9,019
23 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,242	8,533
23 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	10,621	14,791
23 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,986	7,470
23 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
23 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	3	14
23 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
23 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
25 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	411,776	569,026
25 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,277,969	907,588
25 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	47,822	67,123
25 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	121,558	92,066
25 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	40,500	56,006
25 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	488,956	307,903
25 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	243,216	323,242
25 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	431,862	357,151
25 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	79,374	121,379
25 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	86,702	88,370
25 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	864	1,276
25 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	148,891	62,098
25 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
25 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
30 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	50,696	35,032
30 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	36,143	29,172
30 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	12,817	5,072
30 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	8,350	144
30 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,617	7,271
30 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,458	719
30 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	22,829	15,039
30 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	17,568	22,986
30 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,378	7,605
30 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	5,674	5,197
30 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	55	45
30 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	93	126
30 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
30 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
40 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	47,804	55,983
40 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	39,930	43,067
40 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,413	1,128
40 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,150	4,089
40 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,616	3,762
40 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,773	5,923
40 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	22,901	27,268
40 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	17,774	16,303
40 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	17,723	23,459
40 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	14,562	16,038
40 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	151	366
40 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	671	714
40 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
40 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7	99
50 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7	0
50 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	99
50 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
50 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Commercial, financial and agricultural | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Commercial, financial and agricultural | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Real estate – construction and development | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Real estate – construction and development | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Real estate – commercial and farmland | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Real estate – commercial and farmland | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Real estate – residential | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Real estate – residential | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Consumer installment | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Consumer installment | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Other | Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	0	0
60 | Other | Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 0	$ 0