Goodwill and Mortgage Servicing Rights - by Business Segment (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Total goodwill	$ 49,243	$ 49,248	$ 47,800	$ 47,823
Consumer & Community Banking
Goodwill [Line Items]
Total goodwill	31,326	31,311
Corporate & Investment Bank
Goodwill [Line Items]
Total goodwill	7,912	7,913
Commercial Banking
Goodwill [Line Items]
Total goodwill	2,985	2,985
Asset & Wealth Management
Goodwill [Line Items]
Total goodwill	$ 7,020	$ 7,039