Loans - Consumer, Excluding Credit Card Loans, PCI Accretable Yield Activity (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	$ 747,508	$ 724,177	$ 726,835
Consumer, excluding credit card
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	294,979	288,449	292,620
Consumer, excluding credit card | Purchased Credit-Impaired
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	16,167	18,457	19,072
Accretion into interest income	(1,934)	(2,201)	(2,491)
Changes in interest rates on variable-rate loans	(174)	(287)	(449)
Other changes in expected cash flows	533	198	2,325
Balance at December 31	14,592	16,167	18,457
Accretable yield percentage	4.19%	4.31%	4.38%
Total retained loans	46,696	53,055
In Process of Active or Suspended Foreclosure | Consumer, excluding credit card
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	1,500	2,100
In Process of Active or Suspended Foreclosure | Consumer, excluding credit card | Purchased Credit-Impaired
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	$ 3,200	$ 4,800