Amounts Outstanding for Loans and Leases by Segment and Class (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 30,719.9	$ 29,385.5
Allowance for Credit Losses Assigned to Loans and Leases	(269.4)	(278.1)
Net Loans and Leases	30,450.5	29,107.4
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Institutional	8,212.1	7,375.8
Commercial Real Estate	3,107.7	2,955.8
Lease Financing, net	952.5	975.1
Non-U.S.	1,408.4	954.7
Other	187.9	358.6
Total Loans and Leases	13,868.6	12,620.0
Allowance for Credit Losses Assigned to Loans and Leases	(143.1)	(140.9)
Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential Real Estate	9,872.7	10,271.3
Private Client	6,953.1	6,445.6
Other	25.5	48.6
Total Loans and Leases	16,851.3	16,765.5
Allowance for Credit Losses Assigned to Loans and Leases	$ (126.3)	$ (137.2)