Loans and Leases (Delinquency Status) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	$ 34,144.9	$ 33,180.9
Other Real Estate Owned	10.4	8.2
Total Nonperforming Assets	174.4	188.3
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	16,240.1	15,156.5
Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,941.1	9,431.5
Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	3,902.9	3,848.8
Commercial | Lease Financing, net
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	470.6	544.4
Commercial | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	1,769.9	1,137.7
Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	155.6	194.1
Personal
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	17,904.8	18,024.4
Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	8,652.6	8,850.7
Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	9,232.6	9,136.4
Personal | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	19.6	37.3
Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Current	33,814.2	32,898.5
Total Loans and Leases	33,980.9	33,000.8
Performing Financing Receivable | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	106.5	62.9
Performing Financing Receivable | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	50.0	32.3
Performing Financing Receivable | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	10.2	7.1
Performing Financing Receivable | Commercial
Financing Receivable, Recorded Investment [Line Items]
Current	16,149.4	15,077.1
Total Loans and Leases	16,184.9	15,096.9
Performing Financing Receivable | Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Current	9,874.5	9,377.6
Total Loans and Leases	9,899.4	9,388.6
Performing Financing Receivable | Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	3,878.8	3,823.3
Total Loans and Leases	3,889.4	3,832.1
Performing Financing Receivable | Commercial | Lease Financing, net
Financing Receivable, Recorded Investment [Line Items]
Current	470.6	544.4
Total Loans and Leases	470.6	544.4
Performing Financing Receivable | Commercial | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Current	1,769.9	1,137.7
Total Loans and Leases	1,769.9	1,137.7
Performing Financing Receivable | Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Current	155.6	194.1
Total Loans and Leases	155.6	194.1
Performing Financing Receivable | Commercial | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	27.4	10.2
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	23.8	7.8
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.6	2.4
Performing Financing Receivable | Commercial | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.9	5.8
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	0.1	0.9
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.8	4.9
Performing Financing Receivable | Commercial | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	4.2	3.8
Performing Financing Receivable | Commercial | 90 Days or More Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	1.0	2.3
Performing Financing Receivable | Commercial | 90 Days or More Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.2	1.5
Performing Financing Receivable | Personal
Financing Receivable, Recorded Investment [Line Items]
Current	17,664.8	17,821.4
Total Loans and Leases	17,796.0	17,903.9
Performing Financing Receivable | Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	8,499.1	8,679.3
Total Loans and Leases	8,544.1	8,730.6
Performing Financing Receivable | Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Current	9,146.1	9,104.8
Total Loans and Leases	9,232.3	9,136.0
Performing Financing Receivable | Personal | Other
Financing Receivable, Recorded Investment [Line Items]
Current	19.6	37.3
Total Loans and Leases	19.6	37.3
Performing Financing Receivable | Personal | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	79.1	52.7
Performing Financing Receivable | Personal | 30-59 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	39.5	35.2
Performing Financing Receivable | Personal | 30-59 Days Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	39.6	17.5
Performing Financing Receivable | Personal | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	46.1	26.5
Performing Financing Receivable | Personal | 60-89 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	1.6	14.5
Performing Financing Receivable | Personal | 60-89 Days Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	44.5	12.0
Performing Financing Receivable | Personal | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	6.0	3.3
Performing Financing Receivable | Personal | 90 Days or More Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.9	1.6
Performing Financing Receivable | Personal | 90 Days or More Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	2.1	1.7
Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	164.0	180.1
Nonperforming Financing Receivable | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	55.2	59.6
Nonperforming Financing Receivable | Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	41.7	42.9
Nonperforming Financing Receivable | Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	13.5	16.7
Nonperforming Financing Receivable | Personal
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	108.8	120.5
Nonperforming Financing Receivable | Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	108.5	120.1
Nonperforming Financing Receivable | Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	$ 0.3	$ 0.4