Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Recorded Investment Based on Performance of Loans by Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 26,800,290	$ 23,820,691
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	8,285,920	7,828,538
Commercial | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	5,159,805	5,120,096
Commercial | Franchise
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	937,482	948,979
Commercial | Mortgage warehouse lines of credit
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	292,781	144,199
Commercial | Asset-based lending
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	989,018	1,026,056
Commercial | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	878,528	565,680
Commercial | PCI - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	28,306	23,528
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	8,020,276	6,933,252
Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,023,300	760,824
Commercial real estate | Land
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	177,483	141,481
Commercial real estate | Office
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,044,769	939,322
Commercial real estate | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,032,866	902,248
Commercial real estate | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,097,930	892,478
Commercial real estate | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,311,542	976,560
Commercial real estate | Mixed use and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,094,946	2,205,195
Commercial real estate | PCI - commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	237,440	115,144
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	513,066	552,343
Residential real estate, including PCI
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,354,221	1,002,464
Premium finance receivables | Commercial insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	3,442,027	2,841,659
Premium finance receivables | Life insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,935,320	4,373,891
Premium finance receivables | PCI - life insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	139,282	167,903
Consumer and other, including PCI
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	110,178	120,641
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	26,682,702	23,707,457
Performing | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	8,248,696	7,777,554
Performing | Commercial | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	5,125,822	5,085,798
Performing | Commercial | Franchise
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	935,091	932,928
Performing | Commercial | Mortgage warehouse lines of credit
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	292,781	144,199
Performing | Commercial | Asset-based lending
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	988,890	1,025,421
Performing | Commercial | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	877,806	565,680
Performing | Commercial | PCI - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	28,306	23,528
Performing | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	7,994,163	6,914,123
Performing | Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,022,270	759,270
Performing | Commercial real estate | Land
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	176,401	141,374
Performing | Commercial real estate | Office
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,036,735	935,693
Performing | Commercial real estate | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,032,767	901,963
Performing | Commercial real estate | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,091,141	881,725
Performing | Commercial real estate | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,310,629	976,249
Performing | Commercial real estate | Mixed use and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,086,780	2,202,705
Performing | Commercial real estate | PCI - commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	237,440	115,144
Performing | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	505,703	545,196
Performing | Residential real estate, including PCI
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,340,424	986,081
Performing | Premium finance receivables | Commercial insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	3,409,920	2,822,525
Performing | Premium finance receivables | Life insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,934,730	4,373,891
Performing | Premium finance receivables | PCI - life insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	139,282	167,903
Performing | Consumer and other, including PCI
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	109,784	120,184
Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	117,588	113,234
Non-performing | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	37,224	50,984
Non-performing | Commercial | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	33,983	34,298
Non-performing | Commercial | Franchise
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,391	16,051
Non-performing | Commercial | Mortgage warehouse lines of credit
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Non-performing | Commercial | Asset-based lending
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	128	635
Non-performing | Commercial | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	722	0
Non-performing | Commercial | PCI - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Non-performing | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	26,113	19,129
Non-performing | Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,030	1,554
Non-performing | Commercial real estate | Land
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,082	107
Non-performing | Commercial real estate | Office
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	8,034	3,629
Non-performing | Commercial real estate | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	99	285
Non-performing | Commercial real estate | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	6,789	10,753
Non-performing | Commercial real estate | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	913	311
Non-performing | Commercial real estate | Mixed use and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	8,166	2,490
Non-performing | Commercial real estate | PCI - commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Non-performing | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	7,363	7,147
Non-performing | Residential real estate, including PCI
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	13,797	16,383
Non-performing | Premium finance receivables | Commercial insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	32,107	19,134
Non-performing | Premium finance receivables | Life insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	590	0
Non-performing | Premium finance receivables | PCI - life insurance loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Non-performing | Consumer and other, including PCI
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 394	$ 457