Loans - Consumer, Excluding Credit Card Loans, PCI Accretable Yield Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	$ 779,705	$ 735,369	$ 779,705	$ 735,369	$ 747,508
Consumer, excluding credit card
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	316,781	288,214	316,781	288,214	294,979
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	14,034	15,782	14,592	16,167
Accretion into interest income	(430)	(495)	(866)	(1,009)
Changes in interest rates on variable-rate loans	12	(45)	18	(66)
Other changes in expected cash flows	125	33	(3)	183
Ending balance	$ 13,741	$ 15,275	$ 13,741	$ 15,275
Accretable yield percentage	4.18%	4.24%	4.16%	4.28%
Total retained loans	$ 43,806		$ 43,806		46,696
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	1,300		1,300		1,500
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	$ 2,700		$ 2,700		$ 3,200