Amounts Outstanding for Loans and Leases by Segment and Class (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 29,602.1	$ 29,063.9
Allowance for Credit Losses Assigned to Loans and Leases	(300.3)	(294.8)
Net Loans and Leases	29,301.8	28,769.1
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Institutional	7,225.7	6,918.7
Commercial Real Estate	3,073.5	2,981.7
Lease Financing, net	1,010.2	978.8
Non-U.S.	1,278.2	1,057.5
Other	506.7	417.6
Total Loans and Leases	13,094.3	12,354.3
Allowance for Credit Losses Assigned to Loans and Leases	(168.5)	(178.6)
Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential Real Estate	10,518.8	10,708.9
Private Client	5,641.4	5,651.4
Other	347.6	349.3
Total Loans and Leases	16,507.8	16,709.6
Allowance for Credit Losses Assigned to Loans and Leases	$ (131.8)	$ (116.2)