Allowance for Credit Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	$ 7,250	$ 8,642
Loans	7,050,750	7,209,151
Current
Financing receivable recorded investment
Loans	7,029,819	7,171,688
Total Past Due
Financing receivable recorded investment
Loans	20,931	37,463
30 to 59 Days
Financing receivable recorded investment
Loans	10,390	25,836
60 to 89 Days
Financing receivable recorded investment
Loans	2,063	2,456
90 Days or Greater
Financing receivable recorded investment
Loans	8,478	9,171
Commercial, financial and agricultural
Financing receivable recorded investment
Loans	4,156,208	4,497,444
Commercial, financial and agricultural | Domestic | Commercial.
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	50	577
Loans	1,448,522	1,501,852
Commercial, financial and agricultural | Domestic | Commercial. | Current
Financing receivable recorded investment
Loans	1,445,098	1,498,438
Commercial, financial and agricultural | Domestic | Commercial. | Total Past Due
Financing receivable recorded investment
Loans	3,424	3,414
Commercial, financial and agricultural | Domestic | Commercial. | 30 to 59 Days
Financing receivable recorded investment
Loans	3,255	2,534
Commercial, financial and agricultural | Domestic | Commercial. | 60 to 89 Days
Financing receivable recorded investment
Loans	119	303
Commercial, financial and agricultural | Domestic | Commercial. | 90 Days or Greater
Financing receivable recorded investment
Loans	50	577
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	921	307
Loans	2,461,880	2,711,056
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Current
Financing receivable recorded investment
Loans	2,458,459	2,692,076
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Total Past Due
Financing receivable recorded investment
Loans	3,421	18,980
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | 30 to 59 Days
Financing receivable recorded investment
Loans	1,119	18,164
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | 60 to 89 Days
Financing receivable recorded investment
Loans	844	172
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | 90 Days or Greater
Financing receivable recorded investment
Loans	1,458	644
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	71
Loans	245,806	284,536
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | Current
Financing receivable recorded investment
Loans	244,765	284,536
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | Total Past Due
Financing receivable recorded investment
Loans	1,041
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | 30 to 59 Days
Financing receivable recorded investment
Loans	970
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | 90 Days or Greater
Financing receivable recorded investment
Loans	71
Obligations of states and political subdivisions
Financing receivable recorded investment
Loans	1,836,047	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		188
Loans	1,836,047	1,668,113
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Current
Financing receivable recorded investment
Loans	1,834,452	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	1,595	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	1,130	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		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	465	188
Real estate - mortgage
Financing receivable recorded investment
Loans	852,164	867,831
Real estate - mortgage | Domestic | Residential: first lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	4,896	4,937
Loans	412,352	403,658
Real estate - mortgage | Domestic | Residential: first lien | Current
Financing receivable recorded investment
Loans	404,801	394,975
Real estate - mortgage | Domestic | Residential: first lien | Total Past Due
Financing receivable recorded investment
Loans	7,551	8,683
Real estate - mortgage | Domestic | Residential: first lien | 30 to 59 Days
Financing receivable recorded investment
Loans	1,854	2,342
Real estate - mortgage | Domestic | Residential: first lien | 60 to 89 Days
Financing receivable recorded investment
Loans	575	1,212
Real estate - mortgage | Domestic | Residential: first lien | 90 Days or Greater
Financing receivable recorded investment
Loans	5,122	5,129
Real estate - mortgage | Domestic | Residential Junior Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,289	1,055
Loans	439,812	464,173
Real estate - mortgage | Domestic | Residential Junior Lien | Current
Financing receivable recorded investment
Loans	437,822	462,256
Real estate - mortgage | Domestic | Residential Junior Lien | Total Past Due
Financing receivable recorded investment
Loans	1,990	1,917
Real estate - mortgage | Domestic | Residential Junior Lien | 30 to 59 Days
Financing receivable recorded investment
Loans	617	747
Real estate - mortgage | Domestic | Residential Junior Lien | 60 to 89 Days
Financing receivable recorded investment
Loans	84	115
Real estate - mortgage | Domestic | Residential Junior Lien | 90 Days or Greater
Financing receivable recorded investment
Loans	1,289	1,055
Consumer
Financing receivable recorded investment
Loans	41,786	40,966
Consumer | Domestic
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	7	4
Loans	41,786	40,966
Consumer | Domestic | Current
Financing receivable recorded investment
Loans	41,424	40,643
Consumer | Domestic | Total Past Due
Financing receivable recorded investment
Loans	362	323
Consumer | Domestic | 30 to 59 Days
Financing receivable recorded investment
Loans	224	231
Consumer | Domestic | 60 to 89 Days
Financing receivable recorded investment
Loans	131	88
Consumer | Domestic | 90 Days or Greater
Financing receivable recorded investment
Loans	7	4
Foreign.
Financing receivable recorded investment
Loans	164,545	134,797
Foreign. | Foreign
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	16	1,574
Loans	164,545	134,797
Foreign. | Foreign | Current
Financing receivable recorded investment
Loans	162,998	131,672
Foreign. | Foreign | Total Past Due
Financing receivable recorded investment
Loans	1,547	3,125
Foreign. | Foreign | 30 to 59 Days
Financing receivable recorded investment
Loans	1,221	1,319
Foreign. | Foreign | 60 to 89 Days
Financing receivable recorded investment
Loans	310	232
Foreign. | Foreign | 90 Days or Greater
Financing receivable recorded investment
Loans	$ 16	$ 1,574