Fair Value Disclosures (Notional or Contractual Amounts and Fair Values of Off-Balance Sheet Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Residential mortgage loans sold with recourse	$ 667	$ 783
Other loans sold with recourse	4,264	4,594
Letters of credit and financial guarantees	3,462	4,355
Notional Or Contract Amount [Member]
Commitments to extend, originate or purchase credit	49,333	45,333
Residential mortgage loans sold with recourse	667	783
Other loans sold with recourse	4,264	4,594
Letters of credit and financial guarantees	3,462	4,355
Fair Value [Member]
Commitments to extend, originate or purchase credit	97	86
Residential mortgage loans sold with recourse	9	13
Other loans sold with recourse	7	9
Letters of credit and financial guarantees	$ 22	$ 39