Loans and Leases (Delinquency Status) (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
Other Real Estate Owned	7.7	8.2
Total Nonperforming Assets	181.0	188.3
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	15,577.9	15,156.5
Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,422.5	9,431.5
Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	4,039.2	3,848.8
Commercial | Lease Financing, net
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	306.5	544.4
Commercial | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	1,404.6	1,137.7
Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	405.1	194.1
Personal
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	17,845.1	18,024.4
Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	7,994.3	8,850.7
Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,799.6	9,136.4
Personal | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	51.2	37.3
Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Current	33,156.4	32,898.5
Total Loans and Leases	33,249.7	33,000.8
Performing Financing Receivable | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	60.3	62.9
Performing Financing Receivable | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	20.5	32.3
Performing Financing Receivable | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	12.5	7.1
Performing Financing Receivable | Commercial
Financing Receivable, Recorded Investment [Line Items]
Current	15,460.5	15,077.1
Total Loans and Leases	15,504.8	15,096.9
Performing Financing Receivable | Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Current	9,338.9	9,377.6
Total Loans and Leases	9,361.2	9,388.6
Performing Financing Receivable | Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	4,006.3	3,823.3
Total Loans and Leases	4,027.4	3,832.1
Performing Financing Receivable | Commercial | Lease Financing, net
Financing Receivable, Recorded Investment [Line Items]
Current	306.5	544.4
Total Loans and Leases	306.5	544.4
Performing Financing Receivable | Commercial | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Current	1,403.7	1,137.7
Total Loans and Leases	1,404.6	1,137.7
Performing Financing Receivable | Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Current	405.1	194.1
Total Loans and Leases	405.1	194.1
Performing Financing Receivable | Commercial | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	29.6	10.2
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	16.1	7.8
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	13.5	2.4
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Past Due	0.0
Performing Financing Receivable | Commercial | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	8.1	5.8
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	1.7	0.9
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	5.5	4.9
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Past Due	0.9
Performing Financing Receivable | Commercial | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	6.6	3.8
Performing Financing Receivable | Commercial | 90 Days or More Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	4.5	2.3
Performing Financing Receivable | Commercial | 90 Days or More Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	2.1	1.5
Performing Financing Receivable | Personal
Financing Receivable, Recorded Investment [Line Items]
Current	17,695.9	17,821.4
Total Loans and Leases	17,744.9	17,903.9
Performing Financing Receivable | Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	7,876.0	8,679.3
Total Loans and Leases	7,896.3	8,730.6
Performing Financing Receivable | Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Current	9,768.7	9,104.8
Total Loans and Leases	9,797.4	9,136.0
Performing Financing Receivable | Personal | Other
Financing Receivable, Recorded Investment [Line Items]
Current	51.2	37.3
Total Loans and Leases	51.2	37.3
Performing Financing Receivable | Personal | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	30.7	52.7
Performing Financing Receivable | Personal | 30-59 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	10.7	35.2
Performing Financing Receivable | Personal | 30-59 Days Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	20.0	17.5
Performing Financing Receivable | Personal | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	12.4	26.5
Performing Financing Receivable | Personal | 60-89 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	6.3	14.5
Performing Financing Receivable | Personal | 60-89 Days Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	6.1	12.0
Performing Financing Receivable | Personal | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	5.9	3.3
Performing Financing Receivable | Personal | 90 Days or More Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.3	1.6
Performing Financing Receivable | Personal | 90 Days or More Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	2.6	1.7
Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	173.3	180.1
Nonperforming Financing Receivable | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	73.1	59.6
Nonperforming Financing Receivable | Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	61.3	42.9
Nonperforming Financing Receivable | Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	11.8	16.7
Nonperforming Financing Receivable | Personal
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	100.2	120.5
Nonperforming Financing Receivable | Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	98.0	120.1
Nonperforming Financing Receivable | Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	$ 2.2	$ 0.4