Fair Value Disclosures (Earnings Impact of Instruments under the Fair Value Option) (Details) - Borrowings - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Fair Value Option Quantitative Disclosures
Earnings impact	$ (76)	$ (1,744)
Trading Revenues
Fair Value Option Quantitative Disclosures
Earnings impact	26	(1,625)
Interest Income (Expense)
Fair Value Option Quantitative Disclosures
Earnings impact	$ (102)	$ (119)

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

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