Allowance for Credit Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	$ 56,245	$ 59,705
Past due	109,367	84,450
Loans, current	7,392,440	6,810,496
Total loans	7,501,807	6,894,946
30 to 59 Days
Financing receivable recorded investment
Past due	38,297	18,169
60 to 89 Days
Financing receivable recorded investment
Past due	13,241	4,937
90 Days or Greater
Financing receivable recorded investment
Past due	57,829	61,344
Commercial, financial and agricultural
Financing receivable recorded investment
Total loans	3,967,980	3,379,837
Commercial, financial and agricultural | Domestic | Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,339	421
Past due	11,577	5,052
Loans, current	1,795,914	1,287,608
Total loans	1,807,491	1,292,660
Commercial, financial and agricultural | Domestic | Commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	1,910	3,134
Commercial, financial and agricultural | Domestic | Commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	7,610	626
Commercial, financial and agricultural | Domestic | Commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	2,057	1,292
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	49,584	54,878
Past due	75,222	65,017
Loans, current	1,896,412	1,831,730
Total loans	1,971,634	1,896,747
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	24,359	8,058
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	1,036	2,031
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	49,827	54,928
Commercial, financial and agricultural | Domestic | Commercial Real Estate: multifamily
Financing receivable recorded investment
Past due	124	478
Loans, current	188,731	189,952
Total loans	188,855	190,430
Commercial, financial and agricultural | Domestic | Commercial Real Estate: multifamily | 30 to 59 Days
Financing receivable recorded investment
Past due	124	313
Commercial, financial and agricultural | Domestic | Commercial Real Estate: multifamily | 90 Days or Greater
Financing receivable recorded investment
Past due		165
Real estate - construction
Financing receivable recorded investment
Total loans	2,277,991	2,185,883
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	118
Past due	3,592	564
Loans, current	2,274,399	2,185,319
Total loans	2,277,991	2,185,883
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | 30 to 59 Days
Financing receivable recorded investment
Past due	2,821	509
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | 60 to 89 Days
Financing receivable recorded investment
Past due	653	55
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | 90 Days or Greater
Financing receivable recorded investment
Past due	118
Real estate - mortgage
Financing receivable recorded investment
Total loans	1,081,380	1,140,377
Real estate - mortgage | Domestic | Residential First Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	3,434	3,107
Past due	11,114	8,559
Loans, current	410,424	425,342
Total loans	421,538	433,901
Real estate - mortgage | Domestic | Residential First Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	5,157	3,229
Real estate - mortgage | Domestic | Residential First Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	1,944	1,670
Real estate - mortgage | Domestic | Residential First Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	4,013	3,660
Real estate - mortgage | Domestic | Residential Junior Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,377	1,200
Past due	3,941	2,789
Loans, current	655,901	703,687
Total loans	659,842	706,476
Real estate - mortgage | Domestic | Residential Junior Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	739	1,112
Real estate - mortgage | Domestic | Residential Junior Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	1,784	477
Real estate - mortgage | Domestic | Residential Junior Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	1,418	1,200
Consumer
Financing receivable recorded investment
Total loans	42,401	47,800
Consumer | Domestic
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	116	88
Past due	647	630
Loans, current	41,754	47,170
Total loans	42,401	47,800
Consumer | Domestic | 30 to 59 Days
Financing receivable recorded investment
Past due	488	467
Consumer | Domestic | 60 to 89 Days
Financing receivable recorded investment
Past due	40	75
Consumer | Domestic | 90 Days or Greater
Financing receivable recorded investment
Past due	119	88
Foreign
Financing receivable recorded investment
Total loans	132,055	141,049
Foreign | Foreign
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	277	11
Past due	3,150	1,361
Loans, current	128,905	139,688
Total loans	132,055	141,049
Foreign | Foreign | 30 to 59 Days
Financing receivable recorded investment
Past due	2,699	1,347
Foreign | Foreign | 60 to 89 Days
Financing receivable recorded investment
Past due	174	3
Foreign | Foreign | 90 Days or Greater
Financing receivable recorded investment
Past due	$ 277	$ 11