Loans and Allowance for Loan Losses (Details 5) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Nonaccrual Loans
Nonaccrual	$ 553	$ 638
Troubled debt restructured loans that continue to accrue interest	335	252
Troubled debt restructured nonaccrual loans (included in total nonaccrual loans above)	177	221
Commercial and Industrial [Member]
Nonaccrual Loans
Nonaccrual	75	127
Commercial Mortgage [Member]
Nonaccrual Loans
Nonaccrual	101	139
Construction Loans [Member]
Nonaccrual Loans
Nonaccrual		16
Commercial [Member]
Nonaccrual Loans
Nonaccrual	176	282
Residential Mortgage [Member]
Nonaccrual Loans
Nonaccrual	293	285
Home Equity and Other Consumer Loans [Member]
Nonaccrual Loans
Nonaccrual	44	24
Consumer [Member]
Nonaccrual Loans
Nonaccrual	337	309
Nonaccrual Loans Excluding FDIC Covered Loans [Member]
Nonaccrual Loans
Nonaccrual	513	591
Covered Loans [Member]
Nonaccrual Loans
Nonaccrual	$ 40	$ 47