Label	Element	Value
Emerging Markets Breakout Nations Portfolio
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	ck0000836487_SupplementTextBlock	Summary Prospectus and Prospectus Supplement December 6, 2018 Morgan Stanley Institutional Fund, Inc. Supplement dated December 6, 2018 to the Morgan Stanley Institutional Fund, Inc. Summary Prospectus and Prospectus dated April 30, 2018 Emerging Markets Breakout Nations Portfolio (the "Fund")
Risk/Return [Heading]	rr_RiskReturnHeading	Emerging Markets Breakout Nations Portfolio
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Effective January 1, 2019, the Fund's primary benchmark index will change to MSCI Emerging Markets ex China Net Index. Also effective January 1, 2019, Tim Drinkall will no longer serve as a portfolio manager to the Fund. Accordingly, effective January 1, 2019, with respect to the Fund, all references to Mr. Drinkall will be removed from the Summary Prospectus and Prospectus.
Performance Table Market Index Changed	rr_PerformanceTableMarketIndexChanged	Effective January 1, 2019, the Fund's primary benchmark index will change to MSCI Emerging Markets ex China Net Index.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Please retain this supplement for future reference.

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- Definition

Risk/Return Bar Chart and Table.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 4
-Subsection b
-Paragraph 2

+ Details

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- Definition

If the Fund has annual returns for at least one calendar year, provide a table showing the Fund's (A) average annual total return; (B) average annual total return (after taxes on distributions); and (C) average annual total return (after taxes on distributions and redemption). A Money Market Fund should show only the returns described in clause (A) of the preceding sentence. All returns should be shown for 1-, 5-, and 10- calendar year periods ending on the date of the most recently completed calendar year (or for the life of the Fund, if shorter), but only for periods subsequent to the effective date of the Fund's registration statement. The table also should show the returns of an appropriate broad-based securities market index as defined in Instruction 5 to Item 22(b)(7) for the same periods. A Fund that has been in existence for more than 10 years also may include returns for the life of the Fund. A Money Market Fund may provide the Fund's 7-day yield ending on the date of the most recent calendar year or disclose a toll-free (or collect) telephone number that investors can use to obtain the Fund's current 7-day yield. For a Fund (other than a Money Market Fund or a Fund described in General Instruction C.3.(d)(iii)), provide the information in the following table with the specified captions AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, _____)

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 4
-Subsection b
-Paragraph 2
-Subparagraph iii

+ Details

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- Definition

If the Fund selects an index that is different from the index used in a table for the immediately preceding period, explain the reason(s) for the selection of a different index and provide information for both the newly selected and the former index.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 4
-Subsection b
-Paragraph 2
-Subparagraph instructions
-Clause 2
-Exhibit c

+ Details

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- References

No definition available.

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- Definition

Risk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicated

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 2

+ Details

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