Amount of the effect of a change in accounting principle on expense due to presentation on a gross basis.

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Amount of the effect of a change in accounting principle on net revenue.

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Amount of the effect of a change in accounting principle on revenue due to presentation on a gross basis.

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Amount of the effect of a change in accounting principle on revenue due to timing of satisfaction of performance obligations.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Segment, Geographic and Revenue Information (Change in Revenue) (Details) - Revenue from Contracts with Customers - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Revenue	$ 79	$ 108	$ 93	$ 70	$ 350
Gross presentation impact - Expense	79	108	93	70	350
Timing impact - Revenue	4	0	(12)	38	30
Net change in revenue and expense	$ 4	$ 0	$ (12)	$ 38	30
Intersegment Eliminations
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Net change in revenue and expense					48
Brokerage, Clearing and Exchange Fees
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Expense					30
Marketing and Business Development Expense
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Expense					31
Professional Services
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Expense					102
Other
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Expense					187
Advisory
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Revenue					75
Timing impact - Revenue					15
Underwriting
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Revenue					193
Asset Management
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Revenue					30
Timing impact - Revenue					(4)
Other
Change in Revenue as a Result of Application of the New Revenue Recognition Standard
Gross presentation impact - Revenue					52
Timing impact - Revenue					$ 19