Amounts Outstanding for Loans and Leases by Segment and Class (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 28,862.9	$ 29,504.5
Allowance for Credit Losses Assigned to Loans and Leases	(294.1)	(297.9)
Net Loans and Leases	28,568.8	29,206.6
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and Institutional	7,255.6	7,468.5
Commercial Real Estate	2,822.9	2,859.8
Lease Financing, net	1,005.6	1,035.0
Non-U.S.	1,152.7	1,192.3
Other	445.2	341.6
Total Loans and Leases	12,682.0	12,897.2
Allowance for Credit Losses Assigned to Loans and Leases	(159.6)	(166.1)
Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential Real Estate	10,147.9	10,375.2
Private Client	5,900.0	6,130.1
Other	133.0	102.0
Total Loans and Leases	16,180.9	16,607.3
Allowance for Credit Losses Assigned to Loans and Leases	$ (134.5)	$ (131.8)