Regulatory Requirements (Significant U.S. Bank Operating Subsidiaries' Capital) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
U.S. Basel III \| Transitional / Advanced Approach
Regulatory Requirements
Common Equity Tier 1 capital, amount	$ 57,324
Tier 1 capital, amount	64,182
Total capital, amount	74,972
Tier 1 leverage capital, amount	0
Ratio
Tier 1 common capital ratio	12.60%
Tier 1 capital ratio	14.10%
Total capital ratio	16.40%
Tier 1 leverage ratio	7.90%
U.S. Basel I
Regulatory Requirements
Common Equity Tier 1 capital, amount		49,917
Tier 1 capital, amount		61,007
Total capital, amount		66,000
Tier 1 leverage capital, amount		0
Ratio
Tier 1 common capital ratio		12.80%
Tier 1 capital ratio		15.60%
Total capital ratio		16.90%
Tier 1 leverage ratio		7.60%
MSBNA \| U.S. Basel III
Required Capital Ratio
Tier 1 capital capital ratio, required	6.50%
Tier 1 capital ratio, required	8.00%
Total capital ratio, required	10.00%
Teir 1 leverage ratio, required	5.00%
MSBNA \| U.S. Basel III \| Transitional / U.S. Basel I And Basel 2.5 Approach
Regulatory Requirements
Common Equity Tier 1 capital, amount	12,355
Tier 1 capital, amount	12,355
Total capital, amount	14,040
Tier 1 leverage capital, amount	12,355
Ratio
Tier 1 common capital ratio	12.20%
Tier 1 capital ratio	12.20%
Total capital ratio	13.90%
Tier 1 leverage ratio	10.20%
MSBNA \| U.S. Basel I
Regulatory Requirements
Tier 1 capital, amount		11,086
Total capital, amount		12,749
Tier 1 leverage capital, amount		11,086
Ratio
Tier 1 capital ratio		14.60%
Total capital ratio		16.80%
Tier 1 leverage ratio		10.80%
Required Capital Ratio
Tier 1 capital ratio, required		6.00%
Total capital ratio, required		10.00%
Teir 1 leverage ratio, required		5.00%
MSPBNA \| U.S. Basel III
Required Capital Ratio
Tier 1 capital capital ratio, required	6.50%
Tier 1 capital ratio, required	8.00%
Total capital ratio, required	10.00%
Teir 1 leverage ratio, required	5.00%
MSPBNA \| U.S. Basel III \| Transitional / U.S. Basel I And Basel 2.5 Approach
Regulatory Requirements
Common Equity Tier 1 capital, amount	2,468
Tier 1 capital, amount	2,468
Total capital, amount	2,480
Tier 1 leverage capital, amount	2,468
Ratio
Tier 1 common capital ratio	20.30%
Tier 1 capital ratio	20.30%
Total capital ratio	20.40%
Tier 1 leverage ratio	9.40%
MSPBNA \| U.S. Basel I
Regulatory Requirements
Tier 1 capital, amount		2,177
Total capital, amount		2,184
Tier 1 leverage capital, amount		$ 2,177
Ratio
Tier 1 capital ratio		26.50%
Total capital ratio		26.60%
Tier 1 leverage ratio		9.70%
Required Capital Ratio
Tier 1 capital ratio, required		6.00%
Total capital ratio, required		10.00%
Teir 1 leverage ratio, required		5.00%

Name:	ms_RequiredCapitalRatioAbstract
Namespace Prefix:	ms_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Tier 1 Risk Based Common Capital as defined in the regulations.

+ References

No definition available.

+ Details

Name:	ms_TierOneRiskBasedCommonCapital
Namespace Prefix:	ms_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The common equity Tier 1 capital ratio (Tier 1 common equity capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

+ References

No definition available.

+ Details

Name:	ms_TierOneRiskBasedCommonCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	ms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier 1 common capital divided by risk weighted assets as defined by regulations.

+ References

No definition available.

+ Details

Name:	ms_TierOneRiskBasedCommonCapitalToRiskWeightedAssets
Namespace Prefix:	ms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of total capital as defined in the regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1H

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1H

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998

+ Details

Name:	us-gaap_Capital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Total Capital divided by risk weighted assets as defined in the regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1H

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

+ Details

Name:	us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RiskBasedRatiosAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier 1 Leverage Capital divided by average assets as defined in the regulations.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier 1 Risk Based Capital as defined in the regulations.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier 1 capital divided by risk weighted assets as defined by regulations.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=ms_MorganStanleyBankNationalAssociationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ms_MorganStanleyTrustPrivateBankNationalAssociationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ms_BankingRegulationsAxis=ms_UsBaselIiiMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ms_BankingRegulationsAxis=ms_UsBaselIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: