Loans and Leases (Composition of the Loans and Leases Outstanding By Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	$ 31,887,774	$ 28,322,780
Past due loans	228,304	272,770
Current loans	32,190,121	28,608,726
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	22,156,874	18,552,002
Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		12,282,635
Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		542,028
Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	4,650,839	4,403,792
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		310,093
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,012,365	1,013,454
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	9,730,900	9,770,778
Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	353,382	357,385
Consumer | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		2,339,072
Consumer | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		1,780,404
Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		18,552,002
Past due loans		74,146
Current loans		18,477,856
Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		12,282,635
Past due loans	29,698	37,482
Current loans	10,323,095	12,245,153
Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		542,028
Past due loans	17,416	1,890
Current loans	3,038,912	540,138
Non-PCI Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		4,403,792
Past due loans	17,875	28,143
Current loans	4,632,964	4,375,649
Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		310,093
Past due loans	68,342	588
Current loans	22,088,532	309,505
Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		1,013,454
Past due loans	3,353	6,043
Current loans	1,009,012	1,007,411
Non-PCI Loans | Commercial | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		18,157,655
Non-PCI Loans | Commercial | Pass | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		12,050,799
Non-PCI Loans | Commercial | Pass | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		536,682
Non-PCI Loans | Commercial | Pass | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		4,256,456
Non-PCI Loans | Commercial | Pass | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		308,796
Non-PCI Loans | Commercial | Pass | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		1,004,922
Non-PCI Loans | Commercial | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		166,866
Non-PCI Loans | Commercial | Special Mention | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		115,164
Non-PCI Loans | Commercial | Special Mention | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		3,899
Non-PCI Loans | Commercial | Special Mention | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		44,604
Non-PCI Loans | Commercial | Special Mention | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		622
Non-PCI Loans | Commercial | Special Mention | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		2,577
Non-PCI Loans | Commercial | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		158,897
Non-PCI Loans | Commercial | Substandard | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		116,672
Non-PCI Loans | Commercial | Substandard | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		1,447
Non-PCI Loans | Commercial | Substandard | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		34,148
Non-PCI Loans | Commercial | Substandard | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		675
Non-PCI Loans | Commercial | Substandard | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		5,955
Non-PCI Loans | Commercial | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		3
Non-PCI Loans | Commercial | Doubtful | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Commercial | Doubtful | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Commercial | Doubtful | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		3
Non-PCI Loans | Commercial | Doubtful | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Commercial | Doubtful | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Commercial | Ungraded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		68,581
Non-PCI Loans | Commercial | Ungraded | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Commercial | Ungraded | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Commercial | Ungraded | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		68,581
Non-PCI Loans | Commercial | Ungraded | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Commercial | Ungraded | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
Non-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		9,770,778
Past due loans	102,935	132,389
Current loans	9,627,965	9,638,389
Non-PCI Loans | Consumer | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		5,293,917
Past due loans		88,537
Current loans		5,205,380
Non-PCI Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		357,385
Past due loans	5,193	2,992
Current loans	1,190,578	354,393
Non-PCI Loans | Consumer | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		2,339,072
Past due loans	1,919	23,062
Current loans	351,463	2,316,010
Non-PCI Loans | Consumer | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		1,780,404
Past due loans	5,959	17,798
Current loans	537,129	1,762,606
PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	57,027	66,235
Current loans	473,624	492,481
PCD Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		284,329
PCD Loans | Commercial | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		148,412
PCD Loans | Commercial | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		44,290
PCD Loans | Commercial | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		87,970
PCD Loans | Commercial | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		3,657
PCD Loans | Commercial | Ungraded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		0
PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans		274,387
Current loans		240,995
30 to 59 Days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	94,584	136,220
30 to 59 Days past due | Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		42,716
30 to 59 Days past due | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	14,360	20,389
30 to 59 Days past due | Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	7,914	861
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	10,464	18,269
30 to 59 Days past due | Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	34,356	51
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	1,618	3,146
30 to 59 Days past due | Non-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	41,378	67,026
30 to 59 Days past due | Non-PCI Loans | Consumer | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		45,839
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	3,093	977
30 to 59 Days past due | Non-PCI Loans | Consumer | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,735	9,729
30 to 59 Days past due | Non-PCI Loans | Consumer | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,433	10,481
30 to 59 Days past due | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	18,850	26,478
30 to 59 Days past due | PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		13,764
60 to 89 Days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	26,043	51,058
60 to 89 Days past due | Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		14,553
60 to 89 Days past due | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,518	8,774
60 to 89 Days past due | Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	982	331
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	3,196	4,842
60 to 89 Days past due | Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	6,710	411
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	14	195
60 to 89 Days past due | Non-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	14,639	25,721
60 to 89 Days past due | Non-PCI Loans | Consumer | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		18,289
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	1,124	218
60 to 89 Days past due | Non-PCI Loans | Consumer | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	127	3,468
60 to 89 Days past due | Non-PCI Loans | Consumer | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,691	3,746
60 to 89 Days past due | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	4,694	10,784
60 to 89 Days past due | PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		5,608
90 Days or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	107,677	85,492
90 Days or greater | Non-PCI Loans | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		16,877
90 Days or greater | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	12,820	8,319
90 Days or greater | Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	8,520	698
90 Days or greater | Non-PCI Loans | Commercial | Commercial and industrial and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	4,215	5,032
90 Days or greater | Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	27,276	126
90 Days or greater | Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,721	2,702
90 Days or greater | Non-PCI Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	46,918	39,642
90 Days or greater | Non-PCI Loans | Consumer | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		24,409
90 Days or greater | Non-PCI Loans | Consumer | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	976	1,797
90 Days or greater | Non-PCI Loans | Consumer | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	57	9,865
90 Days or greater | Non-PCI Loans | Consumer | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,835	3,571
90 Days or greater | PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	$ 33,483	28,973
90 Days or greater | PCD Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans		$ 14,020