Document and Entity Information	Jun. 18, 2020
Prospectus:
Document Type	497
Document Period End Date	Jun. 18, 2020
Entity Registrant Name	MORGAN STANLEY INSTITUTIONAL FUND INC
Entity Central Index Key	0000836487
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Jun. 18, 2020
Document Effective Date	Jun. 18, 2020
Prospectus Date	Apr. 30, 2020
Emerging Markets Leaders Portfolio \| Class A
Prospectus:
Trading Symbol	MELAX
Emerging Markets Leaders Portfolio \| Class IS
Prospectus:
Trading Symbol	MELSX
Emerging Markets Leaders Portfolio \| Class C
Prospectus:
Trading Symbol	MEMLX
Emerging Markets Leaders Portfolio \| Class I
Prospectus:
Trading Symbol	MELIX
Multi-Asset Portfolio \| Class A
Prospectus:
Trading Symbol	MMPPX
Multi-Asset Portfolio \| Class L
Prospectus:
Trading Symbol	MMPLX
Multi-Asset Portfolio \| Class I
Prospectus:
Trading Symbol	MMPIX
Multi-Asset Portfolio \| Class C
Prospectus:
Trading Symbol	MSMEX
Multi-Asset Portfolio \| Class IS
Prospectus:
Trading Symbol	MSPMX
INTERNATIONAL REAL ESTATE PORTFOLIO \| CLASS I
Prospectus:
Trading Symbol	MSUAX
INTERNATIONAL REAL ESTATE PORTFOLIO \| CLASS A
Prospectus:
Trading Symbol	IERBX
INTERNATIONAL REAL ESTATE PORTFOLIO \| Class L
Prospectus:
Trading Symbol	MSOLX
INTERNATIONAL REAL ESTATE PORTFOLIO \| Class IS
Prospectus:
Trading Symbol	MIREX
INTERNATIONAL REAL ESTATE PORTFOLIO \| Class C
Prospectus:
Trading Symbol	MSIJX

If the value is true, then the document is an amendment to previously-filed/accepted document.

No definition available.

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

The date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

+ References

No definition available.

+ Details

Name:	dei_DocumentCreationDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.

+ References

No definition available.

+ Details

Name:	dei_DocumentEffectiveDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

+ References

No definition available.

+ Details

Name:	dei_DocumentPeriodEndDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:	dei_DocumentType
Namespace Prefix:	dei_
Data Type:	dei:submissionTypeItemType
Balance Type:	na
Period Type:	duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityCentralIndexKey
Namespace Prefix:	dei_
Data Type:	dei:centralIndexKeyItemType
Balance Type:	na
Period Type:	duration

- Definition

One of: N-1A (Mutual Fund), N-1 (Open-End Separate Account with No Variable Annuities), N-2 (Closed-End Investment Company), N-3 (Separate Account Registered as Open-End Management Investment Company), N-4 (Variable Annuity UIT Separate Account), N-5 (Small Business Investment Company), N-6 (Variable Life UIT Separate Account), S-1 or S-3 (Face Amount Certificate Company), S-6 (UIT, Non-Insurance Product).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-T
-Number 232
-Section 313

+ Details

Name:	dei_EntityInvCompanyType
Namespace Prefix:	dei_
Data Type:	dei:invCompanyType
Balance Type:	na
Period Type:	duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityRegistrantName
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:	dei_TradingSymbol
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The date of the prospectus.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 1
-Subsection a
-Paragraph 3

+ Details

Name:	rr_ProspectusDate
Namespace Prefix:	rr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Prospectus Table.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A

+ Details

Name:	rr_ProspectusTable
Namespace Prefix:	rr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=ck0000836487_S000047473Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000149048Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000149050Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000155912Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000149047Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ck0000836487_S000037170Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000114471Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000114473Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000114474Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000155909Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000156277Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ck0000836487_S000002835Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000007763Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000007764Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000113813Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000126916Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000836487_C000155895Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: