Noninterest Revenue and Noninterest Expense - Investment Banking Fees (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Non interest Revenue [Line Items]
Underwriting	$ 5,031	$ 5,268	$ 4,477
Advisory	2,519	2,144	2,095
Total investment banking fees	7,550	7,412	6,572
Equity
Schedule of Non interest Revenue [Line Items]
Underwriting	1,684	1,466	1,200
Debt
Schedule of Non interest Revenue [Line Items]
Underwriting	$ 3,347	$ 3,802	$ 3,277

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