Loans - Consumer, Excluding Credit Card Loans, PCI Accretable Yield Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	$ 832,792	$ 747,508	$ 724,177
Consumer, excluding credit card
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Total retained loans	344,355	294,979	288,449
Consumer, excluding credit card | In the 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	1,500
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	211,798	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	14,592	16,167	18,457
Accretion into interest income	(1,700)	(1,934)	(2,201)
Changes in interest rates on variable-rate loans	279	(174)	(287)
Other changes in expected cash flows	230	533	198
Reclassification from nonaccretable difference	90	0	0
Balance at December 31	$ 13,491	$ 14,592	$ 16,167
Accretable yield percentage	4.20%	4.19%	4.31%
Total retained loans	$ 40,998	$ 46,696
Consumer, excluding credit card | Residential real estate - PCI | Residential real estate | In the 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	$ 2,300	$ 3,200