Loans and Leases - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other U.S. loans and non-U.S. loans, short duration advances	$ 1,900,000,000		$ 1,600,000,000
Demand deposits	55,200,000		191,600,000
Loans held for sale	100,000		9,300,000
Loan agreement term	Loan that are 29 days past due or less are reported as current.
Maximum limit of individual homogeneous loans collective evaluation for impairment and excluded from impaired loan disclosures	250,000
Unfunded loan commitments and standby letters of credit	3,300,000		9,700,000
Total Loans and Leases	29,156,300,000		29,063,900,000
Lower Limit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period for loan to performed under modified term	6 months
Nonperforming Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recorded for nonperforming loans	3,100,000	4,200,000
Total Loans and Leases	67,900,000		72,200,000
Performing Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 41,300,000		$ 41,100,000
Loans, Under 90 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan agreement term	the loan agreement, or interest or principal is more than 90 days contractually past due and the loan is not well-secured and in the process of collection.