Noninterest Revenue and Noninterest Expense - Investment Banking Fees (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule of Noninterest revenue [Line Items]
Underwriting	$ 2,546	$ 2,253	$ 4,829	$ 3,624
Advisory	924	597	1,611	1,092
Total investment banking fees	3,470	2,850	6,440	4,716
Equity
Schedule of Noninterest revenue [Line Items]
Underwriting	1,073	974	2,135	1,301
Debt
Schedule of Noninterest revenue [Line Items]
Underwriting	$ 1,473	$ 1,279	$ 2,694	$ 2,323

Includes (1) underwriting revenue (the spread between the resale price received and the cost of the securities and related expenses) generated through the purchasing, distributing and reselling of new issues of securities (alternatively, could be a secondary offering of a large block of previously issued securities); and (2) fees earned for mergers, acquisitions, divestitures, restructurings, and other types of financial advisory services.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(b),(d))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration