Allowance for Credit Losses (Portfolio Credit Quality) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Loan portfolio by credit quality indicator
2022	$ 2,186,514
2021	2,390,065	$ 3,641,975
2020	1,048,017	1,540,327
2019	590,412	885,554
2018	503,342	616,037
2017/Prior	332,400	241,896
Prior		283,362
Total loans	7,050,750	7,209,151
Commercial, financial and agricultural
Loan portfolio by credit quality indicator
Total loans	4,156,208	4,497,444
Commercial, financial and agricultural | Domestic | Commercial.
Loan portfolio by credit quality indicator
2022	545,274
2021	681,277	1,154,047
2020	101,208	168,461
2019	45,680	78,434
2018	44,737	58,577
2017/Prior	30,346	37,178
Prior		5,155
Total loans	1,448,522	1,501,852
Commercial, financial and agricultural | Domestic | Commercial. | Pass
Loan portfolio by credit quality indicator
2022	511,978
2021	680,788	1,041,763
2020	100,975	167,691
2019	45,000	77,579
2018	44,685	58,439
2017/Prior	30,337	37,104
Prior		5,144
Total loans	1,413,763	1,387,720
Commercial, financial and agricultural | Domestic | Commercial. | Special Review
Loan portfolio by credit quality indicator
2022	381
2021	225	74,559
2020		497
2019		139
2018		81
Total loans	606	75,276
Commercial, financial and agricultural | Domestic | Commercial. | Watch List - Pass
Loan portfolio by credit quality indicator
2022	3,052
2021		33,920
2019	680
Prior		10
Total loans	3,732	33,930
Commercial, financial and agricultural | Domestic | Commercial. | Watch List - Substandard
Loan portfolio by credit quality indicator
2022	29,863
2021	164	3,581
2020	233	273
2019		716
2018	52	57
2017/Prior	1
Prior		1
Total loans	30,313	4,628
Commercial, financial and agricultural | Domestic | Commercial. | Watch List - Doubtful
Loan portfolio by credit quality indicator
2021	100	224
2017/Prior	8	74
Total loans	108	298
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial
Loan portfolio by credit quality indicator
2022	592,637
2021	612,260	1,021,054
2020	535,035	780,449
2019	267,428	292,569
2018	355,473	420,801
2017/Prior	99,047	98,606
Prior		97,577
Total loans	2,461,880	2,711,056
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Pass
Loan portfolio by credit quality indicator
2022	575,325
2021	611,346	1,001,335
2020	479,814	680,777
2019	263,504	288,333
2018	355,473	417,353
2017/Prior	96,759	96,096
Prior		97,119
Total loans	2,382,221	2,581,013
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Special Review
Loan portfolio by credit quality indicator
2022	173
2021	662	929
2020	851	1,292
2018		3,448
2017/Prior		61
Total loans	1,686	5,730
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Watch List - Pass
Loan portfolio by credit quality indicator
2022	17,139
2021	252	18,790
2020		44,059
2019	2,906
2017/Prior		94
Prior		1
Total loans	20,297	62,944
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
2020	54,166	54,097
2019	685	3,899
2017/Prior	2,288	2,355
Prior		456
Total loans	57,139	60,807
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial | Watch List - Doubtful
Loan portfolio by credit quality indicator
2020	204	224
2019	333	337
Prior		1
Total loans	537	562
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily
Loan portfolio by credit quality indicator
2022	64,755
2021	86,768	133,152
2020	60,463	40,897
2019	12,178	78,609
2018	6,211	10,632
2017/Prior	15,431	14,217
Prior		7,029
Total loans	245,806	284,536
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | Pass
Loan portfolio by credit quality indicator
2022	64,755
2021	86,768	133,152
2020	60,342	40,766
2019	12,178	78,609
2018	6,211	10,632
2017/Prior	15,431	14,217
Prior		7,029
Total loans	245,685	284,405
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily | Watch List - Doubtful
Loan portfolio by credit quality indicator
2020	121	131
Total loans	121	131
Obligations of states and political subdivisions
Loan portfolio by credit quality indicator
Total loans	1,836,047	1,668,113
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development
Loan portfolio by credit quality indicator
2022	659,767
2021	766,051	967,431
2020	196,570	335,593
2019	174,039	308,884
2018	32,907	37,124
2017/Prior	6,713	16,642
Prior		2,439
Total loans	1,836,047	1,668,113
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Pass
Loan portfolio by credit quality indicator
2022	639,785
2021	765,586	966,946
2020	196,473	312,389
2019	173,829	308,673
2018	32,907	37,124
2017/Prior	6,713	16,642
Prior		2,439
Total loans	1,815,293	1,644,213
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Special Review
Loan portfolio by credit quality indicator
2019	210	211
Total loans	210	211
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Watch List - Pass
Loan portfolio by credit quality indicator
2020		23,100
Total loans		23,100
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Watch List - Substandard
Loan portfolio by credit quality indicator
2022	19,982
Total loans	19,982
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development | Watch List - Doubtful
Loan portfolio by credit quality indicator
2021	465	485
2020	97	104
Total loans	562	589
Real estate - mortgage
Loan portfolio by credit quality indicator
Total loans	852,164	867,831
Real estate - mortgage | Domestic | Residential: first lien
Loan portfolio by credit quality indicator
2022	110,262
2021	84,981	128,798
2020	51,752	52,812
2019	42,580	57,352
2018	35,871	49,259
2017/Prior	86,906	29,599
Prior		85,838
Total loans	412,352	403,658
Real estate - mortgage | Domestic | Residential: first lien | Pass
Loan portfolio by credit quality indicator
2022	110,081
2021	84,544	128,742
2020	51,752	52,725
2019	42,580	57,249
2018	35,871	49,259
2017/Prior	86,906	29,477
Prior		85,838
Total loans	411,734	403,290
Real estate - mortgage | Domestic | Residential: first lien | Watch List - Substandard
Loan portfolio by credit quality indicator
2022	100
2021	437	56
2019		103
2017/Prior		122
Total loans	537	281
Real estate - mortgage | Domestic | Residential: first lien | Watch List - Doubtful
Loan portfolio by credit quality indicator
2022	81
2020		87
Total loans	81	87
Real estate - mortgage | Domestic | Residential Junior Lien
Loan portfolio by credit quality indicator
2022	72,963
2021	117,776	130,629
2020	95,206	123,062
2019	42,720	59,113
2018	22,661	30,603
2017/Prior	88,486	40,855
Prior		79,911
Total loans	439,812	464,173
Real estate - mortgage | Domestic | Residential Junior Lien | Pass
Loan portfolio by credit quality indicator
2022	72,963
2021	117,776	130,629
2020	95,206	123,062
2019	42,720	59,113
2018	22,661	30,603
2017/Prior	88,486	40,855
Prior		79,911
Total loans	439,812	464,173
Consumer
Loan portfolio by credit quality indicator
Total loans	41,786	40,966
Consumer | Domestic
Loan portfolio by credit quality indicator
2022	27,147
2021	10,697	32,053
2020	1,527	5,693
2019	620	1,370
2018	37	189
2017/Prior	1,758	9
Prior		1,652
Total loans	41,786	40,966
Consumer | Domestic | Pass
Loan portfolio by credit quality indicator
2022	27,147
2021	10,697	32,053
2020	1,527	5,693
2019	620	1,370
2018	37	189
2017/Prior	1,758	9
Prior		1,652
Total loans	41,786	40,966
Foreign.
Loan portfolio by credit quality indicator
Total loans	164,545	134,797
Foreign. | Foreign
Loan portfolio by credit quality indicator
2022	113,709
2021	30,255	74,811
2020	6,256	33,360
2019	5,167	9,223
2018	5,445	8,852
2017/Prior	3,713	4,790
Prior		3,761
Total loans	164,545	134,797
Foreign. | Foreign | Pass
Loan portfolio by credit quality indicator
2022	113,709
2021	30,255	74,811
2020	6,256	33,360
2019	5,167	9,223
2018	5,445	8,852
2017/Prior	3,713	4,790
Prior		3,761
Total loans	$ 164,545	$ 134,797