Noninterest Revenue and Noninterest Expense - Investment Banking Fees (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Schedule of Noninterest revenue [Line Items]
Underwriting	$ 1,335	$ 1,537	$ 2,541	$ 2,685
Advisory	516	631	1,150	1,219
Total investment banking fees	1,851	2,168	3,691	3,904
Equity
Schedule of Noninterest revenue [Line Items]
Underwriting	515	573	776	925
Debt
Schedule of Noninterest revenue [Line Items]
Underwriting	$ 820	$ 964	$ 1,765	$ 1,760

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=114873765&loc=SL114874048-224260

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration