LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loans by Risk Grade (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 14,780,791	$ 14,480,925
9
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income		0
Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	540,980	1,034,506
Year two	276,119	138,136
Year three	114,165	100,900
Year four	88,285	68,339
Year five	52,546	28,655
Prior	57,571	45,190
Revolving Loans Amortized Cost Basis	276,755	211,751
Loans, net of unearned income	1,406,421	1,627,477
Commercial, financial and agricultural | 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	376,496	829,710
Year two	140,359	2,912
Year three	2,340	1,055
Year four	918	387
Year five	219	490
Prior	4,915	4,961
Revolving Loans Amortized Cost Basis	125,123	36,373
Loans, net of unearned income	650,370	875,888
Commercial, financial and agricultural | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	228	1,213
Year two	446	1,512
Year three	8,778	668
Year four	453	996
Year five	766	172
Prior	879	967
Revolving Loans Amortized Cost Basis	3,789	14,317
Loans, net of unearned income	15,339	19,845
Commercial, financial and agricultural | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	101,165	109,352
Year two	63,440	54,266
Year three	41,678	16,932
Year four	12,311	17,968
Year five	15,782	7,027
Prior	8,307	3,905
Revolving Loans Amortized Cost Basis	51,509	68,806
Loans, net of unearned income	294,192	278,256
Commercial, financial and agricultural | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	62,535	86,837
Year two	67,264	71,645
Year three	53,086	74,388
Year four	67,882	37,779
Year five	26,090	15,359
Prior	29,502	23,069
Revolving Loans Amortized Cost Basis	88,234	85,366
Loans, net of unearned income	394,593	394,443
Commercial, financial and agricultural | 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	181	4,061
Year two	3,946	4,269
Year three	3,882	4,772
Year four	3,713	7,443
Year five	5,470	804
Prior	4,130	5,842
Revolving Loans Amortized Cost Basis	6,821	4,352
Loans, net of unearned income	28,143	31,543
Commercial, financial and agricultural | 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	21
Year two	6	72
Year three	461	506
Year four	406	193
Year five	507	3,509
Prior	4,742	1,232
Revolving Loans Amortized Cost Basis	497	632
Loans, net of unearned income	6,619	6,165
Commercial, financial and agricultural | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	375	3,312
Year two	658	3,460
Year three	3,940	2,579
Year four	2,602	3,573
Year five	3,712	1,294
Prior	5,096	5,214
Revolving Loans Amortized Cost Basis	782	1,886
Loans, net of unearned income	17,165	21,318
Commercial, financial and agricultural | 8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one		0
Year two		0
Year three		0
Year four		0
Year five		0
Prior		0
Revolving Loans Amortized Cost Basis		19
Loans, net of unearned income		19
Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	25,503	142,833
Year two	85,231	63,892
Year three	47,777	57,725
Year four	34,995	17,936
Year five	13,245	4,808
Prior	13,378	11,042
Revolving Loans Amortized Cost Basis	9,282	8,759
Loans, net of unearned income	229,411	306,995
Consumer installment | 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	3,954	6,782
Year two	4,203	3,001
Year three	2,252	1,550
Year four	1,119	583
Year five	393	95
Prior	13	1
Revolving Loans Amortized Cost Basis	3,099	667
Loans, net of unearned income	15,033	12,679
Consumer installment | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	0
Year three	0	46
Year four	24	2
Year five	1	0
Prior	55	63
Revolving Loans Amortized Cost Basis	36	42
Loans, net of unearned income	116	153
Consumer installment | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	11,379	15,172
Year two	9,354	6,960
Year three	3,932	2,838
Year four	1,488	887
Year five	497	1,455
Prior	1,595	601
Revolving Loans Amortized Cost Basis	2,943	4,389
Loans, net of unearned income	31,188	32,302
Consumer installment | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	10,160	120,800
Year two	71,425	53,593
Year three	41,168	53,182
Year four	32,182	16,329
Year five	12,267	3,121
Prior	10,878	9,437
Revolving Loans Amortized Cost Basis	3,130	3,556
Loans, net of unearned income	181,210	260,018
Consumer installment | 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	49
Year two	32	127
Year three	75	28
Year four	8	30
Year five	21	3
Prior	160	242
Revolving Loans Amortized Cost Basis	0	8
Loans, net of unearned income	296	487
Consumer installment | 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	2
Year three	5	9
Year four	8	0
Year five	0	0
Prior	141	145
Revolving Loans Amortized Cost Basis	6	0
Loans, net of unearned income	160	156
Consumer installment | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	10	30
Year two	217	209
Year three	345	72
Year four	166	105
Year five	66	134
Prior	536	553
Revolving Loans Amortized Cost Basis	66	97
Loans, net of unearned income	1,406	1,200
Consumer installment | 9
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0
Year two	0
Year three	0
Year four	0
Year five	0
Prior	0
Revolving Loans Amortized Cost Basis	2
Loans, net of unearned income	2
Indirect automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	35,595
Year three	27,732	188,313
Year four	140,150	188,964
Year five	132,835	110,066
Prior	96,656	57,145
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	397,373	580,083
Indirect automobile | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	0
Year three	0	81
Year four	68	31
Year five	26	5,356
Prior	4,862	3,054
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	4,956	8,522
Indirect automobile | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	35,432
Year three	27,695	187,656
Year four	139,757	188,302
Year five	132,451	103,570
Prior	90,484	52,781
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	390,387	567,741
Indirect automobile | 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	0
Year three	0	57
Year four	29	70
Year five	31	62
Prior	85	85
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	145	274
Indirect automobile | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	163
Year three	37	519
Year four	296	561
Year five	327	1,078
Prior	1,225	1,225
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	1,885	3,546
Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	841,347	916,353
Loans, net of unearned income	841,347	916,353
Mortgage warehouse | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	841,347	916,353
Loans, net of unearned income	841,347	916,353
Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	38,623	236,076
Year two	232,591	13,398
Year three	14,205	8,944
Year four	7,227	149,194
Year five	143,831	141,543
Prior	211,101	110,248
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	647,578	659,403
Municipal | 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	36,781	91,692
Year two	93,621	12,685
Year three	13,555	8,944
Year four	7,227	143,741
Year five	138,378	124,929
Prior	192,462	97,923
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	482,024	479,914
Municipal | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	1,842	73,000
Year two	72,018	0
Year three	0	0
Year four	0	0
Year five	0	9,410
Prior	12,968	0
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	86,828	82,410
Municipal | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	39,990
Year two	60,812	713
Year three	650	0
Year four	0	5,453
Year five	5,453	7,204
Prior	2,989	5,489
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	69,904	58,849
Municipal | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	31,394
Year two	6,140	0
Year three	0	0
Year four	0	0
Year five	0	0
Prior	2,682	6,836
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	8,822	38,230
Premium finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	655,200	667,425
Year two	121,458	18,996
Year three	2,973	515
Year four	109	746
Year five	528	121
Prior	60	38
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	780,328	687,841
Premium finance | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	654,607	661,614
Year two	119,382	18,236
Year three	2,973	515
Year four	109	746
Year five	528	121
Prior	60	38
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	777,659	681,270
Premium finance | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	593	5,811
Year two	2,076	760
Year three	0	0
Year four	0	0
Year five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	2,669	6,571
Real estate – construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	435,839	666,893
Year two	489,710	483,145
Year three	318,850	226,138
Year four	118,748	73,061
Year five	60,002	35,841
Prior	65,996	51,658
Revolving Loans Amortized Cost Basis	38,738	69,974
Loans, net of unearned income	1,527,883	1,606,710
Real estate – construction and development | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0
Year two	62
Year three	0
Year four	0
Year five	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Loans, net of unearned income	62
Real estate – construction and development | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	7,884	59,325
Year two	37,592	7,035
Year three	6,222	6,870
Year four	3,962	8,046
Year five	2,633	3,415
Prior	8,030	6,916
Revolving Loans Amortized Cost Basis	1,038	1,293
Loans, net of unearned income	67,361	92,900
Real estate – construction and development | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	426,409	605,254
Year two	451,515	445,496
Year three	295,524	205,444
Year four	67,692	50,181
Year five	42,799	14,672
Prior	27,869	26,915
Revolving Loans Amortized Cost Basis	37,595	68,574
Loans, net of unearned income	1,349,403	1,416,536
Real estate – construction and development | 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	1,614
Year two	528	26,720
Year three	16,913	9,612
Year four	44,673	13,261
Year five	13,946	17,712
Prior	27,151	10,127
Revolving Loans Amortized Cost Basis	105	107
Loans, net of unearned income	103,316	79,153
Real estate – construction and development | 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	685
Year two	0	1,036
Year three	21	3,646
Year four	2,126	1,302
Year five	0	0
Prior	646	4,564
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	2,793	11,233
Real estate – construction and development | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	1,546	15
Year two	13	2,858
Year three	170	566
Year four	295	271
Year five	624	42
Prior	2,300	3,136
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	4,948	6,888
Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	855,942	1,275,475
Year two	1,309,528	1,060,392
Year three	1,151,000	660,156
Year four	707,220	655,451
Year five	583,280	531,935
Prior	1,364,290	1,012,521
Revolving Loans Amortized Cost Basis	80,212	104,076
Loans, net of unearned income	6,051,472	5,300,006
Real estate – commercial and farmland | 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	0
Year three	0	161
Year four	146	0
Year five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	146	161
Real estate – commercial and farmland | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	56,737	7,482
Year two	7,332	540
Year three	354	521
Year four	448	2,131
Year five	2,058	4,375
Prior	12,776	10,663
Revolving Loans Amortized Cost Basis	0	1,138
Loans, net of unearned income	79,705	26,850
Real estate – commercial and farmland | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	566,934	918,939
Year two	853,282	370,703
Year three	410,581	143,591
Year four	171,064	197,942
Year five	169,835	224,712
Prior	485,822	274,665
Revolving Loans Amortized Cost Basis	43,381	67,067
Loans, net of unearned income	2,700,899	2,197,619
Real estate – commercial and farmland | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	227,946	344,777
Year two	424,926	584,814
Year three	580,795	423,241
Year four	432,688	331,024
Year five	241,782	242,573
Prior	631,786	545,745
Revolving Loans Amortized Cost Basis	31,889	34,326
Loans, net of unearned income	2,571,812	2,506,500
Real estate – commercial and farmland | 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	1,679	4,027
Year two	17,197	39,216
Year three	112,473	69,173
Year four	72,218	80,726
Year five	133,334	25,561
Prior	149,037	94,461
Revolving Loans Amortized Cost Basis	4,053	1,274
Loans, net of unearned income	489,991	314,438
Real estate – commercial and farmland | 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	462	0
Year two	0	10,680
Year three	10,369	4,895
Year four	14,008	28,139
Year five	29,841	7,670
Prior	28,571	31,224
Revolving Loans Amortized Cost Basis	884	0
Loans, net of unearned income	84,135	82,608
Real estate – commercial and farmland | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	2,184	250
Year two	6,791	54,439
Year three	36,428	18,574
Year four	16,648	15,489
Year five	6,430	27,044
Prior	56,298	55,763
Revolving Loans Amortized Cost Basis	5	271
Loans, net of unearned income	124,784	171,830
Real estate – residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	629,602	786,803
Year two	718,041	562,538
Year three	426,444	287,286
Year four	204,211	206,739
Year five	143,176	173,832
Prior	547,917	522,873
Revolving Loans Amortized Cost Basis	229,587	255,986
Loans, net of unearned income	2,898,978	2,796,057
Real estate – residential | 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
Prior	15	19
Revolving Loans Amortized Cost Basis	0	0
Loans, net of unearned income	15	19
Real estate – residential | 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	0	37
Year two	36	398
Year three	378	12
Year four	0	121
Year five	96	1,275
Prior	36,139	47,286
Revolving Loans Amortized Cost Basis	1,150	1,402
Loans, net of unearned income	37,799	50,531
Real estate – residential | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	611,704	763,101
Year two	681,564	529,268
Year three	352,543	254,632
Year four	157,688	186,531
Year five	115,923	154,285
Prior	390,335	388,825
Revolving Loans Amortized Cost Basis	186,520	203,491
Loans, net of unearned income	2,496,277	2,480,133
Real estate – residential | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	16,340	19,296
Year two	12,494	19,874
Year three	16,410	15,784
Year four	12,529	11,607
Year five	8,699	14,240
Prior	49,078	53,869
Revolving Loans Amortized Cost Basis	35,969	44,276
Loans, net of unearned income	151,519	178,946
Real estate – residential | 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	532	400
Year two	19,488	1,768
Year three	43,677	3,489
Year four	22,071	3,479
Year five	13,844	1,151
Prior	54,793	12,824
Revolving Loans Amortized Cost Basis	2,787	3,618
Loans, net of unearned income	157,192	26,729
Real estate – residential | 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	618	527
Year two	417	1,843
Year three	933	1,030
Year four	870	334
Year five	399	724
Prior	3,556	3,391
Revolving Loans Amortized Cost Basis	107	255
Loans, net of unearned income	6,900	8,104
Real estate – residential | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one	408	3,442
Year two	4,042	9,387
Year three	12,503	12,339
Year four	11,053	4,667
Year five	4,215	2,157
Prior	14,001	16,659
Revolving Loans Amortized Cost Basis	3,054	2,944
Loans, net of unearned income	$ 49,276	$ 51,595