Loans and Leases (Composition of the Loans and Leases Outstanding By Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	$ 215,919	$ 245,485
Current loans	32,964,932	32,546,490
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	23,097,302	22,558,060
Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	4,946,445	5,013,644
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,022,087	985,424
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	9,650,776	9,771,033
Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	336,065	348,123
Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		67,117
Current loans		22,490,943
Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	27,177	25,071
Current loans	11,313,789	11,139,941
Non-PCI Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	14,266	18,343
Current loans	3,003,632	2,969,346
Non-PCI Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	21,304	20,617
Current loans	4,925,141	4,993,027
Non-PCI Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	64,619	0
Current loans	23,032,683	2,406,291
Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,872	3,086
Current loans	1,020,215	982,338
Non-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	102,034	122,944
Current loans	9,548,742	9,648,089
Non-PCI Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,862	1,339
Current loans	334,203	346,784
Non-PCI Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	4,975	6,579
Current loans	533,702	546,389
PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	49,266	55,424
Current loans	383,507	407,458
30 to 59 Days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	90,526	121,499
30 to 59 Days past due | Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		36,615
30 to 59 Days past due | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	13,153	8,757
30 to 59 Days past due | Non-PCI Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	5,046	12,370
30 to 59 Days past due | Non-PCI Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	13,284	14,532
30 to 59 Days past due | Non-PCI Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	31,760	0
30 to 59 Days past due | Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	277	956
30 to 59 Days past due | Non-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	47,516	66,562
30 to 59 Days past due | Non-PCI Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	266	932
30 to 59 Days past due | Non-PCI Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,246	3,610
30 to 59 Days past due | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	11,250	18,322
60 to 89 Days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	24,562	26,043
60 to 89 Days past due | Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		5,601
60 to 89 Days past due | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,996	2,232
60 to 89 Days past due | Non-PCI Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	303	0
60 to 89 Days past due | Non-PCI Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	4,771	2,842
60 to 89 Days past due | Non-PCI Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	8,070	0
60 to 89 Days past due | Non-PCI 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-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	12,170	14,366
60 to 89 Days past due | Non-PCI Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	944	77
60 to 89 Days past due | Non-PCI Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,213	1,464
60 to 89 Days past due | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	4,322	6,076
90 Days or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	100,831	97,943
90 Days or greater | Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		24,901
90 Days or greater | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	11,028	14,082
90 Days or greater | Non-PCI Loans | Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	8,917	5,973
90 Days or greater | Non-PCI Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	3,249	3,243
90 Days or greater | Non-PCI Loans | Commercial | Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	24,789	0
90 Days or greater | Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,595	1,603
90 Days or greater | Non-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	42,348	42,016
90 Days or greater | Non-PCI Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	652	330
90 Days or greater | Non-PCI Loans | Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,516	1,505
90 Days or greater | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	$ 33,694	$ 31,026