Collateralized Transactions - Gross Secured Financing Balances (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Gross Secured Financing Balances
Securities sold under agreements to repurchase	$ 430,286	$ 341,137
Securities loaned	86,846	57,009
Total included in the offsetting disclosure	517,132	398,146
Trading liabilities— Obligation to return securities received as collateral	6,093	18,067
Total	523,225	416,213
U.S. Treasury and agency securities
Gross Secured Financing Balances
Securities sold under agreements to repurchase	228,058	177,464
Other sovereign government obligations
Gross Secured Financing Balances
Securities sold under agreements to repurchase	154,104	135,806
Securities loaned	1,605	1,805
Corporate equities
Gross Secured Financing Balances
Securities sold under agreements to repurchase	26,552	14,993
Securities loaned	83,220	54,144
Trading liabilities— Obligation to return securities received as collateral	5,852	18,059
Other
Gross Secured Financing Balances
Securities sold under agreements to repurchase	21,572	12,874
Securities loaned	2,021	1,060
Trading liabilities— Obligation to return securities received as collateral	241	8
Overnight and Open
Gross Secured Financing Balances
Securities sold under agreements to repurchase	263,607	180,793
Securities loaned	76,948	42,473
Total included in the offsetting disclosure	340,555	223,266
Trading liabilities— Obligation to return securities received as collateral	6,093	18,067
Total	346,648	241,333
Less than 30 Days
Gross Secured Financing Balances
Securities sold under agreements to repurchase	95,211	104,551
Securities loaned	1	0
Total included in the offsetting disclosure	95,212	104,551
Trading liabilities— Obligation to return securities received as collateral	0	0
Total	95,212	104,551
30-90 Days
Gross Secured Financing Balances
Securities sold under agreements to repurchase	32,238	25,071
Securities loaned	338	317
Total included in the offsetting disclosure	32,576	25,388
Trading liabilities— Obligation to return securities received as collateral	0	0
Total	32,576	25,388
Over 90 Days
Gross Secured Financing Balances
Securities sold under agreements to repurchase	39,230	30,722
Securities loaned	9,559	14,219
Total included in the offsetting disclosure	48,789	44,941
Trading liabilities— Obligation to return securities received as collateral	0	0
Total	$ 48,789	$ 44,941

The aggregate amount of liabilities as of the balance sheet date for obligations incurred in connection with the entity's investments.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(15)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

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

- Definition

The fair value of collateral received by the entity associated with securities borrowed that must be returned if the counterparty fulfills its obligations. It appears on the balance sheet as a liability and has a corresponding asset that appears on the balance sheet called Securities Received as Collateral.

+ References

+ Details

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

- 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.

+ Details

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

- Definition

Amount, before effects of master netting arrangements, of securities loaned to entities in exchange for collateral and funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481395/860-30-55-4

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481420/860-30-50-7

+ Details

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

- Definition

Amount, before effects of master netting arrangements, of securities loaned to entities in exchange for collateral. Includes liabilities not subject to a master netting arrangement and elected not to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-15

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

+ Details

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

- Definition

Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and elected not to be offset.

+ References

+ Details

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

- Details

Name:	us-gaap_CollateralAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=ms_CorporateEquitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=us-gaap_CollateralizedSecuritiesOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis=us-gaap_MaturityOvernightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis=us-gaap_MaturityUpTo30DaysMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis=us-gaap_Maturity30To90DaysMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis=us-gaap_MaturityOver90DaysMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: