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Allowance for Credit Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	$ 7,254	$ 8,642
Loans	7,048,277	7,209,151
Current
Financing receivable recorded investment
Loans	7,027,437	7,171,688
Total Past Due
Financing receivable recorded investment
Loans	20,840	37,463
30 to 59 Days
Financing receivable recorded investment
Loans	10,009	25,836
60 to 89 Days
Financing receivable recorded investment
Loans	2,963	2,456
90 Days or Greater
Financing receivable recorded investment
Loans	7,868	9,171
Commercial, financial and agricultural
Financing receivable recorded investment
Loans	4,278,715	4,497,444
Commercial, financial and agricultural | Domestic | Commercial.
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	442	577
Loans	1,461,620	1,501,852
Commercial, financial and agricultural | Domestic | Commercial. | Current
Financing receivable recorded investment
Loans	1,458,757	1,498,438
Commercial, financial and agricultural | Domestic | Commercial. | Total Past Due
Financing receivable recorded investment
Loans	2,863	3,414
Commercial, financial and agricultural | Domestic | Commercial. | 30 to 59 Days
Financing receivable recorded investment
Loans	2,160	2,534
Commercial, financial and agricultural | Domestic | Commercial. | 60 to 89 Days
Financing receivable recorded investment
Loans	261	303
Commercial, financial and agricultural | Domestic | Commercial. | 90 Days or Greater
Financing receivable recorded investment
Loans	442	577
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing		307
Loans	2,561,545	2,711,056
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Current
Financing receivable recorded investment
Loans	2,556,851	2,692,076
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Total Past Due
Financing receivable recorded investment
Loans	4,694	18,980
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | 30 to 59 Days
Financing receivable recorded investment
Loans	2,973	18,164
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | 60 to 89 Days
Financing receivable recorded investment
Loans	1,384	172
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | 90 Days or Greater
Financing receivable recorded investment
Loans	337	644
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily
Financing receivable recorded investment
Loans	255,550	284,536
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | Current
Financing receivable recorded investment
Loans	255,540	284,536
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | Total Past Due
Financing receivable recorded investment
Loans	10
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | 30 to 59 Days
Financing receivable recorded investment
Loans	10
Obligations of states and political subdivisions
Financing receivable recorded investment
Loans	1,742,698	1,668,113
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	536	188
Loans	1,742,698	1,668,113
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Current
Financing receivable recorded investment
Loans	1,740,821	1,667,092
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Total Past Due
Financing receivable recorded investment
Loans	1,877	1,021
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | 30 to 59 Days
Financing receivable recorded investment
Loans	1,302	499
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | 60 to 89 Days
Financing receivable recorded investment
Loans	39	334
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | 90 Days or Greater
Financing receivable recorded investment
Loans	536	188
Real estate - mortgage
Financing receivable recorded investment
Loans	840,373	867,831
Real estate - mortgage | Domestic | Residential: first lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	4,887	4,937
Loans	398,849	403,658
Real estate - mortgage | Domestic | Residential: first lien | Current
Financing receivable recorded investment
Loans	390,451	394,975
Real estate - mortgage | Domestic | Residential: first lien | Total Past Due
Financing receivable recorded investment
Loans	8,398	8,683
Real estate - mortgage | Domestic | Residential: first lien | 30 to 59 Days
Financing receivable recorded investment
Loans	2,541	2,342
Real estate - mortgage | Domestic | Residential: first lien | 60 to 89 Days
Financing receivable recorded investment
Loans	693	1,212
Real estate - mortgage | Domestic | Residential: first lien | 90 Days or Greater
Financing receivable recorded investment
Loans	5,164	5,129
Real estate - mortgage | Domestic | Residential Junior Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,168	1,055
Loans	441,524	464,173
Real estate - mortgage | Domestic | Residential Junior Lien | Current
Financing receivable recorded investment
Loans	439,718	462,256
Real estate - mortgage | Domestic | Residential Junior Lien | Total Past Due
Financing receivable recorded investment
Loans	1,806	1,917
Real estate - mortgage | Domestic | Residential Junior Lien | 30 to 59 Days
Financing receivable recorded investment
Loans	218	747
Real estate - mortgage | Domestic | Residential Junior Lien | 60 to 89 Days
Financing receivable recorded investment
Loans	420	115
Real estate - mortgage | Domestic | Residential Junior Lien | 90 Days or Greater
Financing receivable recorded investment
Loans	1,168	1,055
Consumer
Financing receivable recorded investment
Loans	41,019	40,966
Consumer | Domestic
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	6	4
Loans	41,019	40,966
Consumer | Domestic | Current
Financing receivable recorded investment
Loans	40,671	40,643
Consumer | Domestic | Total Past Due
Financing receivable recorded investment
Loans	348	323
Consumer | Domestic | 30 to 59 Days
Financing receivable recorded investment
Loans	243	231
Consumer | Domestic | 60 to 89 Days
Financing receivable recorded investment
Loans	99	88
Consumer | Domestic | 90 Days or Greater
Financing receivable recorded investment
Loans	6	4
Foreign.
Financing receivable recorded investment
Loans	145,472	134,797
Foreign. | Foreign
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	215	1,574
Loans	145,472	134,797
Foreign. | Foreign | Current
Financing receivable recorded investment
Loans	144,628	131,672
Foreign. | Foreign | Total Past Due
Financing receivable recorded investment
Loans	844	3,125
Foreign. | Foreign | 30 to 59 Days
Financing receivable recorded investment
Loans	562	1,319
Foreign. | Foreign | 60 to 89 Days
Financing receivable recorded investment
Loans	67	232
Foreign. | Foreign | 90 Days or Greater
Financing receivable recorded investment
Loans	$ 215	$ 1,574

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