Label	Element	Value
Global Discovery Portfolio
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	ck0000836487_SupplementTextBlock	December 12, 2013 Morgan Stanley Institutional Fund, Inc. Supplement dated December 12, 2013 to the Morgan Stanley Institutional Fund, Inc. (the "Fund") Prospectus dated April 30, 2013 of: Global Discovery Portfolio
Risk/Return [Heading]	rr_RiskReturnHeading	Global Discovery Portfolio
Strategy [Heading]	rr_StrategyHeading	The last paragraph in the section of the Fund's Prospectus entitled "Portfolio Summary-Global Discovery Portfolio-Principal Investment Strategies" is hereby deleted and replaced with the following:
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Portfolio may, but it is not required to, use derivative instruments for a variety of purposes, including hedging, risk management, portfolio management or to earn income. The Portfolio's use of derivatives may involve the purchase and sale of derivative instruments such as options and other related instruments and techniques. The Portfolio may utilize foreign currency forward exchange contracts, which are also derivatives, in connection with its investments in foreign securities. Derivative instruments used by the Portfolio will be counted toward the Portfolio's exposure in the types of securities listed above to the extent they have economic characteristics similar to such securities.
Risk [Heading]	rr_RiskHeading	The following is hereby added as the penultimate paragraph in the section of the Fund's Prospectus entitled "Portfolio Summary-Global Discovery Portfolio-Principal Risks:"
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	• *Derivatives.* A derivative instrument often has risks similar to its underlying asset and may have additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which they relate and risks that the transactions may not be liquid. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
Risk Closing [Text Block]	rr_RiskClosingTextBlock	Please retain this supplement for future reference.

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If the Fund is a Money Market Fund, state that An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

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Narrative Risk Disclosure.

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Narrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.

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

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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

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Principal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.

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