Loans - Consumer, Excluding Credit Card Loans, PCI Accretable Yield Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	$ 969,415	$ 924,838	$ 889,907
Consumer, excluding credit card
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	373,637	372,553	364,406
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]
Loans	653	787
Consumer, excluding credit card | Total PCI
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	231,078	216,496
Consumer, excluding credit card | Residential real estate – PCI | Total PCI
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	11,159	11,768	13,491
Accretion into interest income	(1,249)	(1,396)	(1,555)
Changes in interest rates on variable-rate loans	(109)	503	260
Other changes in expected cash flows	(1,379)	284	(428)
Balance at December 31	$ 8,422	$ 11,159	$ 11,768
Accretable yield percentage	4.92%	4.53%	4.35%
Loans	$ 24,034	$ 30,576
Consumer, excluding credit card | Residential real estate – PCI | Total PCI | 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]
Loans	$ 964	$ 1,300