LOANS - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	$ 199,422	$ 38,189
Provision for loan losses	(16,579)	37,047
Loans charged off	(7,574)	(6,718)
Recoveries of loans previously charged off	3,301	2,345
Ending balance, Allowance	178,570	149,524
Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		78,661
Commercial, financial and agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	7,359	4,567
Provision for loan losses	2,575	3,080
Loans charged off	(2,370)	(2,486)
Recoveries of loans previously charged off	727	362
Ending balance, Allowance	8,291	8,110
Commercial, financial and agricultural \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		2,587
Consumer installment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	4,076	3,784
Provision for loan losses	5,806	4,149
Loans charged off	(1,448)	(1,142)
Recoveries of loans previously charged off	356	321
Ending balance, Allowance	8,790	15,124
Consumer installment \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		8,012
Indirect automobile
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	1,929	0
Provision for loan losses	(528)	564
Loans charged off	(829)	(1,231)
Recoveries of loans previously charged off	700	344
Ending balance, Allowance	1,272	3,786
Indirect automobile \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		4,109
Mortgage warehouse
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	3,666	640
Provision for loan losses	(145)	(1)
Loans charged off	0	0
Recoveries of loans previously charged off	0	0
Ending balance, Allowance	3,521	1,102
Mortgage warehouse \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		463
Municipal
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	791	484
Provision for loan losses	(1)	130
Loans charged off	0	0
Recoveries of loans previously charged off	0	0
Ending balance, Allowance	790	522
Municipal \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		(92)
Premium finance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	3,879	2,550
Provision for loan losses	442	4,634
Loans charged off	(1,343)	(831)
Recoveries of loans previously charged off	1,122	684
Ending balance, Allowance	4,100	11,508
Premium finance \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		4,471
Real estate – construction and development
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	45,304	5,995
Provision for loan losses	(22,587)	6,734
Loans charged off	(26)	0
Recoveries of loans previously charged off	167	342
Ending balance, Allowance	22,858	25,319
Real estate – construction and development \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		12,248
Real estate – commercial and farmland
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	88,894	9,666
Provision for loan losses	3,671	15,858
Loans charged off	(1,395)	(928)
Recoveries of loans previously charged off	41	85
Ending balance, Allowance	91,211	51,754
Real estate – commercial and farmland \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		27,073
Real estate – residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance	43,524	10,503
Provision for loan losses	(5,812)	1,899
Loans charged off	(163)	(100)
Recoveries of loans previously charged off	188	207
Ending balance, Allowance	$ 37,737	32,299
Real estate – residential \| Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance, Allowance		$ 19,790

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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