Credit Quality and the Allowance for Loan and Lease Losses - Additional Information (Detail) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Financing Receivable, Impaired [Line Items]
Larger commercial loans, subject to impairment review	$ 3,056		$ 3,056		$ 2,931
Interest income recognized on impaired loans	69	53	172	164
Average impaired loans	$ 3,005	$ 3,100	$ 2,990