Goodwill and Mortgage Servicing Rights - by Business Segment and Corporate (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Goodwill [Line Items]
Total goodwill	$ 50,313	$ 49,256	$ 49,248	$ 47,819	$ 47,811	$ 47,823
Corporate
Goodwill [Line Items]
Total goodwill	727		0
Consumer & Community Banking
Goodwill [Line Items]
Total goodwill	31,472		31,311
Corporate & Investment Bank
Goodwill [Line Items]
Total goodwill	7,906		7,913
Commercial Banking
Goodwill [Line Items]
Total goodwill	2,986		2,985
Asset & Wealth Management
Goodwill [Line Items]
Total goodwill	$ 7,222		$ 7,039