Goodwill and Mortgage Servicing Rights - by Business Segment (Details) - USD ($) $ in Millions	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Total goodwill	$ 49,256	$ 49,243	$ 49,248	$ 47,811	$ 47,800	$ 47,823
Consumer & Community Banking
Goodwill [Line Items]
Total goodwill	31,335		31,311
Corporate & Investment Bank
Goodwill [Line Items]
Total goodwill	7,915		7,913
Commercial Banking
Goodwill [Line Items]
Total goodwill	2,985		2,985
Asset & Wealth Management
Goodwill [Line Items]
Total goodwill	$ 7,021		$ 7,039