LOANS (Not Covered by Share Agreements (Past Due Financing Receivables)) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 23,601	$ 31,928
Current	9,912,064	8,259,441
Nonaccrual	87,386	76,548
Total	10,023,051	8,367,917
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	17,400	25,322
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,481	2,501
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	720	4,105
Commercial and industrial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,867	9,924
Current	2,504,170	2,491,110
Nonaccrual	21,762	29,775
Total	2,534,799	2,530,809
Commercial and industrial | Paycheck Protection Program ("PPP")
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1	0
Current	957,784	0
Nonaccrual	0	0
Total	957,785	0
Commercial and industrial | Owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,982	4,177
Current	1,759,649	1,461,589
Nonaccrual	13,775	6,938
Total	1,776,406	1,472,704
Commercial and industrial | Non-owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,817	695
Current	1,902,003	1,493,619
Nonaccrual	14,661	1,563
Total	1,921,481	1,495,877
Commercial and industrial | Real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,542	5,761
Current	859,784	1,020,153
Nonaccrual	894	1,167
Total	863,220	1,027,081
Commercial and industrial | 30-59 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,825	5,121
Commercial and industrial | 30-59 Days Past Due | Paycheck Protection Program ("PPP")
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1	0
Commercial and industrial | 30-59 Days Past Due | Owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,815	3,487
Commercial and industrial | 30-59 Days Past Due | Non-owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,143	614
Commercial and industrial | 30-59 Days Past Due | Real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,446	5,689
Commercial and industrial | 60-89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,322	904
Commercial and industrial | 60-89 Days Past Due | Paycheck Protection Program ("PPP")
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial and industrial | 60-89 Days Past Due | Owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	167	690
Commercial and industrial | 60-89 Days Past Due | Non-owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,674	81
Commercial and industrial | 60-89 Days Past Due | Real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	96	72
Commercial and industrial | 90 Days or More Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	720	3,899
Commercial and industrial | 90 Days or More Past Due | Paycheck Protection Program ("PPP")
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial and industrial | 90 Days or More Past Due | Owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial and industrial | 90 Days or More Past Due | Non-owner occupied commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial and industrial | 90 Days or More Past Due | Real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Agricultural and agricultural real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,688	3,839
Current	694,150	541,455
Nonaccrual	18,688	20,543
Total	714,526	565,837
Agricultural and agricultural real estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,688	3,734
Agricultural and agricultural real estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	79
Agricultural and agricultural real estate | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	26
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,758	4,370
Current	825,047	814,840
Nonaccrual	13,637	13,067
Total	840,442	832,277
Residential real estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,675	4,166
Residential real estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	83	24
Residential real estate | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	180
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	946	3,162
Current	409,477	436,675
Nonaccrual	3,969	3,495
Total	414,392	443,332
Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	807	2,511
Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	139	651
Consumer | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 0	$ 0