Amounts Outstanding for Loans and Leases by Segment and Class (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 29,542.7	$ 29,063.9
Allowance for Credit Losses Assigned to Loans and Leases	(298.6)	(294.8)
Net Loans and Leases	29,244.1	28,769.1
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Institutional	7,316.5	6,918.7
Commercial Real Estate	3,002.4	2,981.7
Lease Financing, net	1,011.6	978.8
Non-U.S.	1,038.1	1,057.5
Other	631.0	417.6
Total Loans and Leases	12,999.6	12,354.3
Allowance for Credit Losses Assigned to Loans and Leases	(170.6)	(178.6)
Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential Real Estate	10,435.3	10,708.9
Private Client	5,751.4	5,651.4
Other	356.4	349.3
Total Loans and Leases	16,543.1	16,709.6
Allowance for Credit Losses Assigned to Loans and Leases	$ (128.0)	$ (116.2)