Goodwill and Mortgage Servicing Rights - by Business Segment (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Goodwill [Line Items]
Total goodwill	$ 47,483	$ 47,488	$ 47,507	$ 47,309	$ 47,300	$ 47,288
Consumer & Community Banking
Goodwill [Line Items]
Total goodwill	30,995		31,013
Corporate & Investment Bank
Goodwill [Line Items]
Total goodwill	6,771		6,776
Commercial Banking
Goodwill [Line Items]
Total goodwill	2,860		2,860
Asset & Wealth Management
Goodwill [Line Items]
Total goodwill	$ 6,857		$ 6,858