Loans and Leases (Delinquency Status) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	$ 34,557.1	$ 33,180.9
Other Real Estate Owned	14.2	8.2
Total Nonperforming Assets	166.4	188.3
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	16,672.0	15,156.5
Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	9,983.5	9,431.5
Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	3,995.9	3,848.8
Commercial | Lease Financing, net
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	381.5	544.4
Commercial | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	2,027.2	1,137.7
Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	283.9	194.1
Personal
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	17,885.1	18,024.4
Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	8,224.3	8,850.7
Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	9,624.9	9,136.4
Personal | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	35.9	37.3
Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Current	34,245.6	32,898.5
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	34,404.9	33,000.8
Performing Financing Receivable | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	95.8	62.9
Performing Financing Receivable | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	55.2	32.3
Performing Financing Receivable | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	8.3	7.1
Performing Financing Receivable | Commercial
Financing Receivable, Recorded Investment [Line Items]
Current	16,599.1	15,077.1
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	16,621.3	15,096.9
Performing Financing Receivable | Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Current	9,939.5	9,377.6
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	9,945.0	9,388.6
Performing Financing Receivable | Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	3,968.0	3,823.3
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	3,983.7	3,832.1
Performing Financing Receivable | Commercial | Lease Financing, net
Financing Receivable, Recorded Investment [Line Items]
Current	381.5	544.4
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	381.5	544.4
Performing Financing Receivable | Commercial | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Current	2,026.2	1,137.7
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	2,027.2	1,137.7
Performing Financing Receivable | Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Current	283.9	194.1
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	283.9	194.1
Performing Financing Receivable | Commercial | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	11.5	10.2
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.0	7.8
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	7.6	2.4
Performing Financing Receivable | Commercial | 30-59 Days Past Due | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Past Due	0.9
Performing Financing Receivable | Commercial | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	5.5	5.8
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	2.3	0.9
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.1	4.9
Performing Financing Receivable | Commercial | 60-89 Days Past Due | Non-U.S.
Financing Receivable, Recorded Investment [Line Items]
Past Due	0.1
Performing Financing Receivable | Commercial | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	5.2	3.8
Performing Financing Receivable | Commercial | 90 Days or More Past Due | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Past Due	0.2	2.3
Performing Financing Receivable | Commercial | 90 Days or More Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	5.0	1.5
Performing Financing Receivable | Personal
Financing Receivable, Recorded Investment [Line Items]
Current	17,646.5	17,821.4
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	17,783.6	17,903.9
Performing Financing Receivable | Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	8,105.9	8,679.3
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	8,125.0	8,730.6
Performing Financing Receivable | Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Current	9,504.7	9,104.8
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	9,622.7	9,136.0
Performing Financing Receivable | Personal | Other
Financing Receivable, Recorded Investment [Line Items]
Current	35.9	37.3
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	35.9	37.3
Performing Financing Receivable | Personal | 30-59 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	84.3	52.7
Performing Financing Receivable | Personal | 30-59 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	7.3	35.2
Performing Financing Receivable | Personal | 30-59 Days Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	77.0	17.5
Performing Financing Receivable | Personal | 60-89 Days Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	49.7	26.5
Performing Financing Receivable | Personal | 60-89 Days Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	8.9	14.5
Performing Financing Receivable | Personal | 60-89 Days Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	40.8	12.0
Performing Financing Receivable | Personal | 90 Days or More Past Due
Financing Receivable, Recorded Investment [Line Items]
Past Due	3.1	3.3
Performing Financing Receivable | Personal | 90 Days or More Past Due | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Past Due	2.9	1.6
Performing Financing Receivable | Personal | 90 Days or More Past Due | Private Client
Financing Receivable, Recorded Investment [Line Items]
Past Due	0.2	1.7
Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	152.2	180.1
Nonperforming Financing Receivable | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	50.7	59.6
Nonperforming Financing Receivable | Commercial | Commercial and Institutional
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	38.5	42.9
Nonperforming Financing Receivable | Commercial | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	12.2	16.7
Nonperforming Financing Receivable | Personal
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	101.5	120.5
Nonperforming Financing Receivable | Personal | Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	99.3	120.1
Nonperforming Financing Receivable | Personal | Private Client
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases (Net of unearned income of $63.5 and $103.6)	$ 2.2	$ 0.4