Loans and Leases (Borrower Ratings) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	$ 33,423.0	$ 33,180.9
1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	18,166.6	17,910.4
4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	14,725.9	14,688.3
6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	530.5	582.2
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	15,577.9	15,156.5
Commercial | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,143.1	8,968.9
Commercial | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	6,230.5	5,945.5
Commercial | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	204.3	242.1
Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,422.5	9,431.5
Commercial | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	6,408.2	6,360.6
Commercial | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	2,866.7	2,897.2
Commercial | Commercial and Institutional | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	147.6	173.7
Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	4,039.2	3,848.8
Commercial | Real Estate | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	2,013.0	1,822.6
Commercial | Real Estate | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	1,984.0	1,992.7
Commercial | Real Estate | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	42.2	33.5
Commercial | Lease Financing, net
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	306.5	544.4
Commercial | Lease Financing, net | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	227.0	377.0
Commercial | Lease Financing, net | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	79.5	133.1
Commercial | Lease Financing, net | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	0.0	34.3
Commercial | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	1,404.6	1,137.7
Commercial | Non-U.S. | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	300.0	313.8
Commercial | Non-U.S. | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	1,090.1	823.3
Commercial | Non-U.S. | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	14.5	0.6
Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	405.1	194.1
Commercial | Other | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	194.9	94.9
Commercial | Other | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	210.2	99.2
Commercial | Other | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	0.0	0.0
Personal
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	17,845.1	18,024.4
Personal | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,023.5	8,941.5
Personal | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	8,495.4	8,742.8
Personal | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	326.2	340.1
Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	7,994.3	8,850.7
Personal | Real Estate | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	2,684.6	3,014.9
Personal | Real Estate | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	5,009.4	5,516.7
Personal | Real Estate | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	300.3	319.1
Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,799.6	9,136.4
Personal | Private Client | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	6,314.2	5,908.3
Personal | Private Client | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	3,459.5	3,207.1
Personal | Private Client | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	25.9	21.0
Personal | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	51.2	37.3
Personal | Other | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	24.7	18.3
Personal | Other | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	26.5	19.0
Personal | Other | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	$ 0.0	$ 0.0