Loans - Consumer, Excluding Credit Card Loan Portfolio, PCI Accretable Yield Activity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	$ 844,195	$ 756,971	$ 832,792
Consumer, excluding credit card
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	353,871	304,917	344,355
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	1,100		1,200
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	220,038		211,798
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	13,491	14,592
Accretion into interest income	(407)	(436)
Changes in interest rates on variable-rate loans	76	6
Other changes in expected cash flows	(486)	(128)
Ending balance	$ 12,674	$ 14,034
Accretable yield percentage	4.35%	4.14%
Total retained loans	$ 39,743		40,998
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	$ 2,100		$ 2,300