Loans and Leases (Composition of the Loans and Leases Outstanding by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	$ 32,791,975	$ 28,881,496
Past Due	245,485	272,770
Current	32,546,490	28,608,726
30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	121,499	136,220
60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	26,043	51,058
90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	97,943	85,492
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	22,558,060	18,836,331
Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		18,306,067
Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		211,156
Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		246,867
Commercial | Doubtful
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		3,660
Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		68,581
Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	9,771,033	10,045,165
Current		9,879,384
Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		80,790
Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		31,329
Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		53,662
Construction and land development | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	985,424
Construction and land development | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	970,865
Construction and land development | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	12,162
Construction and land development | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	2,397
Construction and land development | Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	348,123
Construction and land development | Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	932
Construction and land development | Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	77
Construction and land development | Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	330
Commercial and industrial | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	5,013,644
Commercial and industrial | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	4,846,634
Commercial and industrial | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	50,429
Commercial and industrial | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	60,249
Commercial and industrial | Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	56,332
Non-PCI Loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		18,552,002
Past Due		74,146
Current		18,477,856
Non-PCI Loans | Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		42,716
Non-PCI Loans | Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		14,553
Non-PCI Loans | Commercial | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		16,877
Non-PCI Loans | Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	9,771,033	9,770,778
Past Due	122,944	132,389
Current	9,648,089	9,638,389
Non-PCI Loans | Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	66,562	67,026
Non-PCI Loans | Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	14,366	25,721
Non-PCI Loans | Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	42,016	39,642
Non-PCI Loans | Construction and land development | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	985,424	1,013,454
Past Due	3,086	6,043
Current	982,338	1,007,411
Non-PCI Loans | Construction and land development | Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	956	3,146
Non-PCI Loans | Construction and land development | Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	527	195
Non-PCI Loans | Construction and land development | Commercial | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,603	2,702
Non-PCI Loans | Construction and land development | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		1,004,922
Non-PCI Loans | Construction and land development | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		2,577
Non-PCI Loans | Construction and land development | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		5,955
Non-PCI Loans | Construction and land development | Commercial | Doubtful
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Construction and land development | Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Construction and land development | Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	348,123	357,385
Past Due	1,339	2,992
Current	346,784	354,393
Non-PCI Loans | Construction and land development | Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	932	977
Non-PCI Loans | Construction and land development | Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	77	218
Non-PCI Loans | Construction and land development | Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	330	1,797
Non-PCI Loans | Mortgage | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		12,282,635
Past Due		37,482
Current		12,245,153
Non-PCI Loans | Mortgage | Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		20,389
Non-PCI Loans | Mortgage | Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		8,774
Non-PCI Loans | Mortgage | Commercial | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		8,319
Non-PCI Loans | Mortgage | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		12,050,799
Non-PCI Loans | Mortgage | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		115,164
Non-PCI Loans | Mortgage | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		116,672
Non-PCI Loans | Mortgage | Commercial | Doubtful
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Mortgage | Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Mortgage | Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		5,293,917
Current		5,205,380
Non-PCI Loans | Mortgage | Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		45,839
Non-PCI Loans | Mortgage | Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		18,289
Non-PCI Loans | Mortgage | Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		24,409
Non-PCI Loans | Other commercial real estate | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		542,028
Past Due		1,890
Current		540,138
Non-PCI Loans | Other commercial real estate | Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		861
Non-PCI Loans | Other commercial real estate | Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		331
Non-PCI Loans | Other commercial real estate | Commercial | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		698
Non-PCI Loans | Other commercial real estate | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		536,682
Non-PCI Loans | Other commercial real estate | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		3,899
Non-PCI Loans | Other commercial real estate | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		1,447
Non-PCI Loans | Other commercial real estate | Commercial | Doubtful
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Other commercial real estate | Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Commercial and industrial | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	5,013,644	4,403,792
Past Due	20,617	28,143
Current	4,993,027	4,375,649
Non-PCI Loans | Commercial and industrial | Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	14,532	18,269
Non-PCI Loans | Commercial and industrial | Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,842	4,842
Non-PCI Loans | Commercial and industrial | Commercial | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,243	5,032
Non-PCI Loans | Commercial and industrial | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		4,256,456
Non-PCI Loans | Commercial and industrial | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		44,604
Non-PCI Loans | Commercial and industrial | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		34,148
Non-PCI Loans | Commercial and industrial | Commercial | Doubtful
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		3
Non-PCI Loans | Commercial and industrial | Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		68,581
Non-PCI Loans | Other | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	22,558,060	310,093
Past Due	67,117	588
Current	22,490,943	309,505
Non-PCI Loans | Other | Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	36,615	51
Non-PCI Loans | Other | Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	5,601	411
Non-PCI Loans | Other | Commercial | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	24,901	126
Non-PCI Loans | Other | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		308,796
Non-PCI Loans | Other | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		622
Non-PCI Loans | Other | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		675
Non-PCI Loans | Other | Commercial | Doubtful
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Other | Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
Non-PCI Loans | Revolving mortgage | Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		2,339,072
Current		2,316,010
Non-PCI Loans | Revolving mortgage | Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		9,729
Non-PCI Loans | Revolving mortgage | Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		3,468
Non-PCI Loans | Revolving mortgage | Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		9,865
Non-PCI Loans | Consumer | Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		1,780,404
Past Due		17,798
Current		1,762,606
Non-PCI Loans | Consumer | Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		10,481
Non-PCI Loans | Consumer | Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		3,746
Non-PCI Loans | Consumer | Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		3,571
PCD Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	462,882	558,716
Past Due	55,424	66,235
Current	407,458	492,481
PCD Loans | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	18,322
Past Due	18,322	26,478
PCD Loans | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	6,076
Past Due	6,076	10,784
PCD Loans | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases	31,026
Past Due	$ 31,026	28,973
PCD Loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		284,329
PCD Loans | Commercial | Pass
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		148,412
PCD Loans | Commercial | Special mention
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		44,290
PCD Loans | Commercial | Substandard
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		87,970
PCD Loans | Commercial | Doubtful
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		3,657
PCD Loans | Commercial | Ungraded
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		0
PCD Loans | Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans and leases		274,387
Current		240,995
PCD Loans | Consumer Portfolio Segment | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		13,764
PCD Loans | Consumer Portfolio Segment | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		5,608
PCD Loans | Consumer Portfolio Segment | 90 days or greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		$ 14,020