Loans - Purchased Credit-Impaired Accretable Yields (Details) (Consumer, excluding credit card, Purchased Credit-Impaired [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Consumer, excluding credit card \| Purchased Credit-Impaired [Member]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Beginning Balance	$ 19,464	$ 19,717	$ 18,457	$ 19,072
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	(565)	(638)	(1,138)	(1,296)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Changes in Interest Rates on Variable Rate Loans	49	(33)	(110)	(173)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications to Nonaccretable Difference	(342)	521	1,397	1,964
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Ending Balance	$ 18,606	$ 19,567	$ 18,606	$ 19,567
Accretable Yield Percentage	4.38%	4.45%	4.36%	4.47%

The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The current period recognition due to accretion of the excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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- Definition

The change in the estimate of cash flows expected to be collected, after acquisition of a loan, which results in a decrease in accretable yield (for example, if it is probable that expected cash flows will be less than previously expected). This relates to loans not accounted for as a debt security, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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