Asset Quality and Allowances for Loan and Lease Losses and Unfunded Loan Commitments and Letters Of Credit (Rollforward of Allowance for Unfunded Loan Commitments and Letters of Credit) (Details) (USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Asset Quality [Abstract]
Beginning balance	$ 188	$ 296
Net change in allowance for unfunded loan commitments and letters of credit	14	(78)
Ending balance	$ 202	$ 218