Regulatory Requirements (Broker-Dealer Regulatory Capital Requirements) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
MS&Co.
Regulatory Requirements
Net capital	$ 12,661	$ 10,142
Excess net capital	10,303	8,018
MSSB LLC
Regulatory Requirements
Net capital	2,919	2,567
Excess net capital	$ 2,759	$ 2,400

The amount by which actual net capital exceeds (does not exceed) required net capital under the Securities and Exchange Commission regulations.

No definition available.

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- Definition

The amount by which actual net capital exceeds (does not exceed) the greater required net capital under the Securities and Exchange Commission regulations and the Commodity Exchange Act for futures commission merchants.

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No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Net capital is equal to the net worth of the broker dealer, less certain items such as exchange memberships, carrying value of securities not readily marketable, haircuts on marketable securities in proprietary accounts, furniture and equipment and other illiquid assets as defined.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

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