Loans - Consumer, Excluding Credit Card Loan Portfolio, PCI Accretable Yield Activity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 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	$ 804,293	$ 735,304	$ 804,293	$ 735,304	$ 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	331,732	288,379	331,732	288,379	294,979
Consumer, excluding credit card | In Process of Active or Suspended Foreclosure
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	1,200		1,200		1,500
Consumer, excluding credit card | Residential real estate
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	201,097		201,097		162,719
Consumer, excluding credit card | Residential real estate – PCI | Residential real estate
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	13,741	15,275	14,592	16,167
Accretion into interest income	(424)	(471)	(1,290)	(1,480)
Changes in interest rates on variable-rate loans	3	(75)	21	(141)
Other changes in expected cash flows	511	242	508	425
Reclassifications from nonaccretable difference	90	0	90	0
Ending balance	$ 13,921	$ 14,971	$ 13,921	$ 14,971
Accretable yield percentage	4.22%	4.10%	4.18%	4.22%
Total retained loans	$ 42,236		$ 42,236		46,696
Consumer, excluding credit card | Residential real estate – PCI | Residential real estate | In Process of Active or Suspended Foreclosure
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	$ 2,400		$ 2,400		$ 3,200