Loan and Lease Segment and Class Balances Segregated by Borrower Ratings into "One to Three", "Four to Five" and "Six to Nine" (Watch List) Categories (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	$ 30,697.6	$ 29,385.5
1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	14,994.8	13,955.8
4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	14,976.2	14,620.2
6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases	726.6	809.5
Commercial
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	8,042.6	7,375.8
Commercial Real Estate	3,075.5	2,955.8
Lease Financing, net	926.4	975.1
Non-U.S.	1,334.0	954.7
Other	612.9	358.6
Total Loans and Leases	13,991.4	12,620.0
Commercial | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	4,853.8	4,432.5
Commercial Real Estate	1,203.5	1,053.7
Lease Financing, net	504.1	685.7
Non-U.S.	588.6	442.8
Other	520.9	157.7
Total Loans and Leases	7,670.9	6,772.4
Commercial | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	3,072.8	2,801.5
Commercial Real Estate	1,736.3	1,748.7
Lease Financing, net	418.0	285.0
Non-U.S.	744.4	511.9
Other	92.0	200.9
Total Loans and Leases	6,063.5	5,548.0
Commercial | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Commercial and Institutional	116.0	141.8
Commercial Real Estate	135.7	153.4
Lease Financing, net	4.3	4.4
Non-U.S.	1.0
Total Loans and Leases	257.0	299.6
Personal
Financing Receivable, Recorded Investment [Line Items]
Residential Real Estate	9,992.6	10,271.3
Private Client	6,630.5	6,445.6
Other	83.1	48.6
Total Loans and Leases	16,706.2	16,765.5
Personal | 1 to 3 Category
Financing Receivable, Recorded Investment [Line Items]
Residential Real Estate	3,075.4	3,204.6
Private Client	4,177.9	3,957.6
Other	70.6	21.2
Total Loans and Leases	7,323.9	7,183.4
Personal | 4 to 5 Category
Financing Receivable, Recorded Investment [Line Items]
Residential Real Estate	6,452.4	6,563.6
Private Client	2,447.8	2,481.2
Other	12.5	27.4
Total Loans and Leases	8,912.7	9,072.2
Personal | 6 to 9 Category (Watch List)
Financing Receivable, Recorded Investment [Line Items]
Residential Real Estate	464.8	503.1
Private Client	4.8	6.8
Total Loans and Leases	$ 469.6	$ 509.9