Loans, Lending Commitments and Related Allowance for Credit Losses - Loans Held for Investment before Allowance by Credit Quality and Origination Year (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 219,116	$ 204,554
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	6,036	6,213
Current Fiscal Year	65	88
One Year Ago	50	166
Two Years Ago	28	104
Three Years Ago	90	54
Four Years Ago	35
Prior	0	133
Total	6,304	6,758
Corporate \| Investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	2,083	2,350
Current Fiscal Year	53	0
One Year Ago	0	0
Two Years Ago	0	15
Three Years Ago	15	29
Four Years Ago	9
Prior	0	0
Total	2,160	2,394
Corporate \| Non-investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	3,953	3,863
Current Fiscal Year	12	88
One Year Ago	50	166
Two Years Ago	28	89
Three Years Ago	75	25
Four Years Ago	26
Prior	0	133
Total	4,144	4,364
Secured lending facilities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	35,896	31,734
Current Fiscal Year	3,292	2,994
One Year Ago	2,756	2,782
Two Years Ago	2,529	365
Three Years Ago	285	80
Four Years Ago	0
Prior	970	1,543
Total	45,728	39,498
Secured lending facilities \| Investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	10,512	9,494
Current Fiscal Year	818	1,535
One Year Ago	1,423	392
Two Years Ago	286	0
Three Years Ago	0	0
Four Years Ago	0
Prior	100	356
Total	13,139	11,777
Secured lending facilities \| Non-investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	25,384	22,240
Current Fiscal Year	2,474	1,459
One Year Ago	1,333	2,390
Two Years Ago	2,243	365
Three Years Ago	285	80
Four Years Ago	0
Prior	870	1,187
Total	32,589	27,721
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	176	170
Current Fiscal Year	1,811	1,328
One Year Ago	1,219	2,184
Two Years Ago	2,100	1,864
Three Years Ago	1,888	756
Four Years Ago	430
Prior	1,064	2,376
Total	8,688	8,678
Commercial real estate \| Investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	0	0
Current Fiscal Year	112	261
One Year Ago	409	284
Two Years Ago	245	370
Three Years Ago	145	0
Four Years Ago	0
Prior	0	195
Total	911	1,110
Commercial real estate \| Non-investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	176	170
Current Fiscal Year	1,699	1,067
One Year Ago	810	1,900
Two Years Ago	1,855	1,494
Three Years Ago	1,743	756
Four Years Ago	430
Prior	1,064	2,181
Total	7,777	7,568
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	169	149
Current Fiscal Year	7,671	9,137
One Year Ago	8,605	13,740
Two Years Ago	13,165	13,690
Three Years Ago	13,153	8,450
Four Years Ago	8,053
Prior	14,185	15,209
Total	65,001	60,375
Residential real estate \| Less than or equal to 80%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	169	149
Current Fiscal Year	6,935	8,168
One Year Ago	7,703	12,650
Two Years Ago	12,125	12,763
Three Years Ago	12,253	8,017
Four Years Ago	7,640
Prior	13,161	14,106
Total	59,986	55,853
Residential real estate \| Greater than 80%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	0	0
Current Fiscal Year	736	969
One Year Ago	902	1,090
Two Years Ago	1,040	927
Three Years Ago	900	433
Four Years Ago	413
Prior	1,024	1,103
Total	5,015	4,522
Residential real estate \| Greater than or equal to 740
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	126	108
Current Fiscal Year	6,403	7,390
One Year Ago	6,946	10,927
Two Years Ago	10,444	11,075
Three Years Ago	10,646	6,916
Four Years Ago	6,591
Prior	10,848	11,642
Total	52,004	48,058
Residential real estate \| 680-739
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	38	33
Current Fiscal Year	1,151	1,517
One Year Ago	1,449	2,424
Two Years Ago	2,346	2,376
Three Years Ago	2,274	1,430
Four Years Ago	1,363
Prior	2,932	3,131
Total	11,553	10,911
Residential real estate \| Less than or equal to 679
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	5	8
Current Fiscal Year	117	230
One Year Ago	210	389
Two Years Ago	375	239
Three Years Ago	233	104
Four Years Ago	99
Prior	405	436
Total	1,444	1,406
Securities-based lending and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	81,862	78,066
Current Fiscal Year	1,926	2,585
One Year Ago	2,052	2,748
Two Years Ago	2,219	872
Three Years Ago	686	849
Four Years Ago	759
Prior	3,891	4,125
Total	93,395	89,245
Securities-based lending
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	73,585	71,474
Current Fiscal Year	1,003	1,612
One Year Ago	962	1,128
Two Years Ago	642	165
Three Years Ago	100	0
Four Years Ago	39
Prior	231	215
Total	76,562	74,594
Other \| Investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	6,672	5,230
Current Fiscal Year	562	627
One Year Ago	434	816
Two Years Ago	463	330
Three Years Ago	103	435
Four Years Ago	239
Prior	1,214	2,096
Total	9,687	9,534
Other \| Non-investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	1,605	1,362
Current Fiscal Year	361	346
One Year Ago	656	804
Two Years Ago	1,114	377
Three Years Ago	483	414
Four Years Ago	481
Prior	2,446	1,814
Total	$ 7,146	$ 5,117

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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

+ Details

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

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestRevolving
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalNoninvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ms_SecuredLendingFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanToValueAxis=ms_DebttoValueRatioLessthanorEqualto80PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanToValueAxis=ms_DebttoValueRatioGreaterthan80PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditScoreFicoAxis=ms_FICOScoreGreaterthanorEqualto740Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditScoreFicoAxis=ms_FICOScoreBetween680and739Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditScoreFicoAxis=ms_FICOScoreLessthan680Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ms_SecuritiesBasedLendingandOtherLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ms_SecuritiesBasedLendingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ms_OtherLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: