Loans and Leases (Composition of the Loans and Leases Outstanding By Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	$ 170,374	$ 245,485
Current loans	32,345,815	32,546,490
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	22,229,345	22,558,060
Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	5,266,266	5,013,644
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,247,680	985,424
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	9,913,589	9,771,033
Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	391,768	348,123
Non-PCD Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		67,117
Current loans		22,490,943
Non-PCD Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	20,961	25,071
Current loans	11,604,593	11,139,941
Non-PCD Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	8,713	18,343
Current loans	2,994,215	2,969,346
Non-PCD Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	23,233	20,617
Current loans	5,243,033	4,993,027
Non-PCD Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	54,564	0
Current loans	22,174,781	2,406,291
Non-PCD Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,657	3,086
Current loans	1,246,023	982,338
Non-PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	72,092	122,944
Current loans	9,841,497	9,648,089
Non-PCD Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,266	1,339
Current loans	389,502	346,784
Non-PCD Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	4,614	6,579
Current loans	630,794	546,389
PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	43,718	55,424
Current loans	329,537	407,458
30 to 59 Days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	61,934	121,499
30 to 59 Days past due | Non-PCD Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		36,615
30 to 59 Days past due | Non-PCD Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	7,210	8,757
30 to 59 Days past due | Non-PCD Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	752	12,370
30 to 59 Days past due | Non-PCD Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	10,309	14,532
30 to 59 Days past due | Non-PCD Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	18,504	0
30 to 59 Days past due | Non-PCD Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	233	956
30 to 59 Days past due | Non-PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	32,023	66,562
30 to 59 Days past due | Non-PCD Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	477	932
30 to 59 Days past due | Non-PCD Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,197	3,610
30 to 59 Days past due | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	11,407	18,322
60 to 89 Days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	27,296	26,043
60 to 89 Days past due | Non-PCD Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		5,601
60 to 89 Days past due | Non-PCD Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	5,553	2,232
60 to 89 Days past due | Non-PCD Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,245	0
60 to 89 Days past due | Non-PCD Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	3,234	2,842
60 to 89 Days past due | Non-PCD Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	10,032	0
60 to 89 Days past due | Non-PCD Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	0	527
60 to 89 Days past due | Non-PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	12,064	14,366
60 to 89 Days past due | Non-PCD Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,719	77
60 to 89 Days past due | Non-PCD Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,122	1,464
60 to 89 Days past due | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	5,200	6,076
90 Days or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	81,144	97,943
90 Days or greater | Non-PCD Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		24,901
90 Days or greater | Non-PCD Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	8,198	14,082
90 Days or greater | Non-PCD Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	6,716	5,973
90 Days or greater | Non-PCD Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	9,690	3,243
90 Days or greater | Non-PCD Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	26,028	0
90 Days or greater | Non-PCD Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,424	1,603
90 Days or greater | Non-PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	28,005	42,016
90 Days or greater | Non-PCD Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	70	330
90 Days or greater | Non-PCD Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,295	1,505
90 Days or greater | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	$ 27,111	$ 31,026