Loans and Allowance for Loan Losses (Schedule of Current, Accruing Past Due and Nonaccrual Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	$ 43,679,910	$ 43,716,353
Non-accrual with an ALL	229,355	113,519
Non-accrual without an ALL	51,177	14,542
Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	22,780,954	22,066,656
Non-accrual with an ALL	133,237	57,507
Non-accrual without an ALL	48,736	11,904
Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	12,394,853	12,650,313
Non-accrual with an ALL	32,723	5,115
Non-accrual without an ALL	2,412	2,638
Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	8,504,103	8,999,384
Non-accrual with an ALL	63,395	50,897
Non-accrual without an ALL	29	0
Commercial, financial and agricultural | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	14,498,966	13,874,416
Non-accrual with an ALL	77,025	48,008
Non-accrual without an ALL	20,443	11,299
Owner-occupied | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	8,281,988	8,192,240
Non-accrual with an ALL	56,212	9,499
Non-accrual without an ALL	28,293	605
Investment properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	11,377,755	11,644,047
Non-accrual with an ALL	29,300	1,785
Non-accrual without an ALL	1,644	1,688
1-4 family properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	620,904	616,933
Non-accrual with an ALL	2,618	2,172
Non-accrual without an ALL	768	950
Land and development | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	396,194	389,333
Non-accrual with an ALL	805	1,158
Non-accrual without an ALL	0	0
Consumer mortgages | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	5,391,282	5,214,443
Non-accrual with an ALL	43,863	36,847
Non-accrual without an ALL	0	0
Home equity | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,784,356	1,757,038
Non-accrual with an ALL	11,620	6,830
Non-accrual without an ALL	0	0
Credit cards | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	191,046	203,612
Non-accrual with an ALL	0	0
Non-accrual without an ALL	0	0
Other consumer loans | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,137,419	1,824,291
Non-accrual with an ALL	7,912	7,220
Non-accrual without an ALL	29	0
Current
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	43,344,404	43,522,724
Current | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	22,581,014	21,980,288
Current | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	12,356,619	12,640,761
Current | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	8,406,771	8,901,675
Current | Commercial, financial and agricultural | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	14,389,845	13,798,639
Current | Owner-occupied | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	8,191,169	8,181,649
Current | Investment properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	11,345,548	11,639,614
Current | 1-4 family properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	615,804	613,049
Current | Land and development | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	395,267	388,098
Current | Consumer mortgages | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	5,341,023	5,163,417
Current | Home equity | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,764,827	1,742,412
Current | Credit cards | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	187,714	200,047
Current | Other consumer loans | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,113,207	1,795,799
Accruing 30-89 Days Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	51,182	62,195
Accruing 30-89 Days Past Due | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	15,934	15,520
Accruing 30-89 Days Past Due | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3,099	1,799
Accruing 30-89 Days Past Due | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	32,149	44,876
Accruing 30-89 Days Past Due | Commercial, financial and agricultural | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	10,425	15,033
Accruing 30-89 Days Past Due | Owner-occupied | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	5,509	487
Accruing 30-89 Days Past Due | Investment properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,263	960
Accruing 30-89 Days Past Due | 1-4 family properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,714	762
Accruing 30-89 Days Past Due | Land and development | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	122	77
Accruing 30-89 Days Past Due | Consumer mortgages | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	6,396	13,969
Accruing 30-89 Days Past Due | Home equity | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	7,813	7,795
Accruing 30-89 Days Past Due | Credit cards | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,669	1,843
Accruing 30-89 Days Past Due | Other consumer loans | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	16,271	21,269
Accruing 90 Days or Greater Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3,792	3,373
Accruing 90 Days or Greater Past Due | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	2,033	1,437
Accruing 90 Days or Greater Past Due | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,759	1,936
Accruing 90 Days or Greater Past Due | Commercial, financial and agricultural | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,228	1,437
Accruing 90 Days or Greater Past Due | Owner-occupied | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	805	0
Accruing 90 Days or Greater Past Due | Investment properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due | 1-4 family properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due | Land and development | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due | Consumer mortgages | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	210
Accruing 90 Days or Greater Past Due | Home equity | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	96	1
Accruing 90 Days or Greater Past Due | Credit cards | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,663	1,722
Accruing 90 Days or Greater Past Due | Other consumer loans | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	3
Total Accruing Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	54,974	65,568
Total Accruing Past Due | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	17,967	16,957
Total Accruing Past Due | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3,099	1,799
Total Accruing Past Due | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	33,908	46,812
Total Accruing Past Due | Commercial, financial and agricultural | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	11,653	16,470
Total Accruing Past Due | Owner-occupied | Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	6,314	487
Total Accruing Past Due | Investment properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,263	960
Total Accruing Past Due | 1-4 family properties | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,714	762
Total Accruing Past Due | Land and development | Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	122	77
Total Accruing Past Due | Consumer mortgages | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	6,396	14,179
Total Accruing Past Due | Home equity | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	7,909	7,796
Total Accruing Past Due | Credit cards | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3,332	3,565
Total Accruing Past Due | Other consumer loans | Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	$ 16,271	$ 21,272