XML 84 R205.htm IDEA: XBRL DOCUMENT v3.4.0.3
Label Element Value
Multi-Asset Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Multi-Asset Portfolio
Objective [Heading] rr_ObjectiveHeading Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Multi-Asset Portfolio (the "Portfolio") seeks total return. The Portfolio's "Adviser," Morgan Stanley Investment Management Inc., seeks to achieve this objective with an emphasis on positive absolute return and controlling downside portfolio risk.
Expense [Heading] rr_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The table below describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio. For purchases of Class A shares, you may qualify for a sales charge discount if the cumulative net asset value ("NAV") of Class A shares of the Portfolio purchased in a single transaction, together with the NAV of all Class A shares of other portfolios of Morgan Stanley Institutional Fund, Inc. (the "Fund") or Class A shares of other Morgan Stanley Multi-Class Funds (as defined in the section of this Prospectus entitled "Shareholder Information—Exchange Privilege") held in Related Accounts (as defined in the section of this Prospectus entitled "Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares"), amounts to $25,000 or more. More information about this combined purchase discount and other discounts is available from your authorized financial intermediary and on page 20 of this Prospectus in the section entitled "Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares."
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect Portfolio performance. During the most recent fiscal year, the Portfolio's portfolio turnover rate was 355% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 355.00%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates "Acquired Fund Fees and Expenses" in the table is an estimate of those expenses.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

The example below is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds.


The example assumes that you invest $10,000 in the Portfolio, your investment has a 5% return each year and that the Portfolio's operating expenses remain the same (except that the example incorporates the fee waiver and/or expense reimbursement arrangement for only the first year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption If You SOLD Your Shares:
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If You HELD Your Shares:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The Adviser seeks to achieve the Portfolio's investment objective by emphasizing positive absolute return while actively controlling downside portfolio risk. To implement this approach, the Adviser will take long and short positions in a range of securities, other instruments and asset classes to express its investment themes. The Adviser may implement these positions either directly by purchasing securities or (specifically in the case of short positions) through the use of derivatives.


The Adviser's top-down investment approach focuses on asset class, sector, region, country and currency selection as opposed to individual security selection. The Portfolio's allocations are the result of directional views of the markets or individual asset classes taken by the Adviser based on the results of its fundamental and quantitative research. The Portfolio may at times invest a substantial portion of its assets in one or more countries (including emerging market countries) or regions. The Portfolio's investments may be U.S. and non-U.S. dollar denominated.


The Portfolio may invest in real estate investment trusts ("REITs") and similar entities established outside the United States ("foreign real estate companies"). In addition, the Portfolio may invest in fixed income securities issued or guaranteed by foreign governments or supranational organizations or any of their instrumentalities, including debt obligations of governmental issuers located in emerging market or developing countries and sovereign debt, as well as fixed income securities that are rated below "investment grade" or are not rated, but are of equivalent quality. These fixed income securities are often referred to as "high yield securities" or "junk bonds." High yield securities are fixed income securities rated below Baa3 by Moody's Investors Service, Inc. ("Moody's"), below BBB– by Standard & Poor's Rating Group, a division of The McGraw-Hill Companies, Inc. ("S&P") or below BBB– by Fitch Ratings Inc. ("Fitch"), or if unrated considered by the Adviser to be of equivalent quality.


The Portfolio may invest in asset-backed securities. The Portfolio may also invest in privately placed and restricted securities. The mortgage-backed securities in which the Portfolio may invest include mortgage pass-through securities which represent a participation interest in a pool of mortgage loans originated by U.S. governmental or private lenders such as banks. The Portfolio may also invest in other investment companies, including exchange-traded funds ("ETFs").


The Portfolio will use derivative instruments for a variety of purposes, including as part of its investment strategies, 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 futures, options, swaps, structured investments (including commodity-linked notes) and other related instruments and techniques. The Portfolio may also invest in currency derivatives, including, but not limited to, foreign currency forward exchange contracts, and currency and currency index futures and options contracts for hedging and non-hedging purposes. The use of these currency derivatives may allow the Portfolio to obtain net long or net negative (short) exposure to selected currencies. At times, the Portfolio may enter into "cross-currency" transactions involving currencies other than those in which securities held or proposed to be purchased are denominated. 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 Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

There is no assurance that the Portfolio will achieve its investment objective, and you can lose money investing in this Portfolio. The principal risks of investing in the Portfolio include:


•  Equity Securities. In general, prices of equity securities are more volatile than those of fixed income securities. The prices of equity securities fluctuate, and sometimes widely fluctuate, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic and political conditions.


•  Fixed Income Securities. Fixed income securities are subject to the risk of the issuer's inability to meet principal and interest payments on its obligations (i.e., credit risk) and are subject to price volatility resulting from, among other things, interest rate sensitivity, market perception of the creditworthiness of the issuer and general market liquidity (i.e., market risk). The historically low interest rate environment increases the risks associated with rising interest rates, including the potential for periods of volatility and increased redemptions. The Portfolio may face a heightened level of risk, especially since the Federal Reserve Board has ended its quantitative easing program and has begun to raise rates. The Portfolio may be subject to liquidity risk, which may result from the lack of an active market and the reduced number and capacity of traditional market participants to make a market in fixed-income securities. The Portfolio is not limited as to the maturities of the securities in which it may invest. Securities with longer durations are likely to be more sensitive to changes in interest rates, generally making them more volatile than securities with shorter durations. Lower rated fixed income securities have greater volatility because there is less certainty that principal and interest payments will be made as scheduled. Investing in emerging markets intensifies this risk, because lower quality fixed income securities are more volatile in price.


•  High Yield Securities ("Junk Bonds"). The Portfolio's investments in high yield securities expose it to a substantial degree of credit risk. High yield securities may be issued by companies that are restructuring, are smaller and less creditworthy or are more highly indebted than other companies, and therefore they may have more difficulty making scheduled payments of principal and interest. High yield securities may experience reduced liquidity, and sudden and substantial decreases in price. An economic downturn affecting an issuer of high yield securities may result in an increased incidence of default. In the event of a default, the Portfolio may incur additional expenses to seek recovery.


•  Mortgage-Backed Securities. Mortgage-backed securities entail prepayment risk, which generally increases during a period of falling interest rates. Rising interest rates tend to discourage refinancings, with the result that the average life and volatility of mortgage-backed securities will increase and market price will decrease. Rates of prepayment, faster or slower than expected by the Adviser, could reduce the Portfolio's yield, increase the volatility of the Portfolio and/or cause a decline in NAV. Mortgage-backed securities are also subject to extension risk, which is the risk that rising interest rates could cause mortgages or other obligations underlying the securities to be prepaid more slowly than expected, thereby lengthening the duration of such securities, increasing their sensitivity to interest rate changes and causing their prices to decline. Certain mortgage-backed securities may be more volatile and less liquid than other traditional types of debt securities. In addition, an unexpectedly high rate of defaults on the mortgages held by a mortgage pool may adversely affect the value of a mortgage-backed security and could result in losses to the Portfolio. Investments in mortgage-backed securities may give rise to a form of leverage and may cause the Portfolio's turnover rate to appear higher. Leverage may cause the Portfolio to be more volatile than if the Portfolio had not been leveraged.


•  REITs and Foreign Real Estate Companies. Investing in REITs and foreign real estate companies exposes investors to the risks of owning real estate directly, as well as to risks that relate specifically to the way in which REITs and foreign real estate companies are organized and operated. Operating REITs and foreign real estate companies requires specialized management skills and the Portfolio indirectly bears management expenses along with the direct expenses of the Portfolio. REITs are also subject to certain provisions under federal tax law and the failure of a company to qualify as a REIT could have adverse consequences for the Portfolio. In addition, foreign real estate companies may be subject to the laws, rules and regulations governing those entities and their failure to comply with those laws, rules and regulations could negatively impact the performance of those entities.


•  Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political, economic and market risks. There also may be greater market volatility, less reliable financial information, higher transaction and custody costs, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets, which have historically been considered stable, may become more volatile and subject to increased risk due to ongoing developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. The risks of investing in emerging market countries are greater than risks associated with investments in foreign developed countries. Because the Portfolio may at times invest a substantial portion of its assets in one or more countries (including emerging market countries) or regions, it may be more susceptible to an adverse event effecting those countries or regions than a portfolio that was not so invested. In addition, a substantial portion of the Portfolio's investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of the investment will fluctuate with the U.S. dollar exchange rates. To the extent hedged by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions could reduce or preclude the opportunity for gain if the value of the currency moves in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Portfolio's securities are not denominated. The use of foreign currency forward exchange contracts involves the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.


•  Sovereign Debt Securities. Investing in sovereign debt securities will expose the Portfolio to the direct or indirect consequences of political, social or economic changes in the countries that issue the securities. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when it becomes due, due to factors such as debt service burden, political constraints, cash flow problems and other national economic factors. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part.


•  Asset-Backed Securities. Asset-backed securities involve the risk that various federal and state consumer laws and other legal and economic factors may result in the collateral backing the securities being insufficient to support payment on the securities. Some asset-backed securities also entail prepayment risk, which may vary depending on the type of asset.


•  U.S. Government Securities. The U.S. government securities in which the Portfolio invests can be subject to two types of risk: credit risk and interest rate risk. When the general level of interest rates goes up, the prices of most fixed-income securities go down. When the general level of interest rates goes down, the prices of most fixed-income securities go up. While the credit risk associated with U.S. government securities generally is considered to be minimal, the interest rate risk can be substantial. With respect to U.S. government securities that are not backed by the full faith and credit of the United States, there is the risk that the U.S. Government will not provide financial support to such U.S. government agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law.


•  Liquidity. The Portfolio's investments in restricted and illiquid securities may entail greater risk than investments in other types of securities. These securities may be more difficult to sell, particularly in times of market turmoil. Additionally, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Illiquid securities may be more difficult to value. If the Portfolio is forced to sell an illiquid security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss.


•  Investment Company Securities. Subject to the limitations set forth in the Investment Company Act of 1940, as amended (the "1940 Act"), or as otherwise permitted by the SEC, the Portfolio may acquire shares in other investment companies, including foreign investment companies and ETFs, which may be managed by the Adviser or its affiliates. The market value of the shares of other investment companies may differ from the NAV of the Portfolio. The shares of closed-end investment companies frequently trade at a discount to their NAV. As a shareholder in an investment company, the Portfolio would bear its ratable share of that entity's expenses, including its investment advisory and administration fees. At the same time, the Portfolio would continue to pay its own advisory and administration fees and other expenses. As a result, the Portfolio and its shareholders, in effect, will be absorbing duplicate levels of fees with respect to investments in other investment companies.


•  Small and Medium Capitalization Companies. Investments in small and medium capitalization companies may involve greater risks than investments in larger, more established companies. The securities issued by small and medium capitalization companies may be less liquid, and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.


•  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 the derivative instrument relates 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. Investments in currency derivatives may substantially change the Portfolio's exposure to currency exchange rates and could result in losses to the Portfolio if currencies do not perform as the Adviser expects. Foreign currency forward exchange contracts and currency futures and options contracts create exposure to currencies in which the Portfolio's securities are not denominated.


•  Non-Diversification. Because the Portfolio is non-diversified, it may be more susceptible to an adverse event affecting a portfolio investment than a diversified portfolio and a decline in the value of that instrument would cause the Portfolio's overall value to decline to a greater degree.


Shares of the Portfolio are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney There is no assurance that the Portfolio will achieve its investment objective, and you can lose money investing in this Portfolio.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Because the Portfolio is non-diversified, it may be more susceptible to an adverse event affecting a portfolio investment than a diversified portfolio and a decline in the value of that instrument would cause the Portfolio's overall value to decline to a greater degree.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution Shares of the Portfolio are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance Information
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The bar chart and table below provide some indication of the risks of investing in the Portfolio by showing the Portfolio's Class I shares' performance from year-to-year and by showing how the Portfolio's average annual returns for the past one year period and since inception compare with those of a broad measure of market performance and a customized index, as well as an index that represents a group of similar mutual funds, over time. The performance of the other Classes, which is shown in the table below, will differ because the Classes have different ongoing fees. The Portfolio's returns in the table include the maximum applicable sales charge for Class A and assume you sold your shares at the end of each period (unless otherwise noted). The Portfolio's past performance, before and after taxes, is not necessarily an indication of how the Portfolio will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free (800) 548-7786.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table below provide some indication of the risks of investing in the Portfolio by showing the Portfolio's Class I shares' performance from year-to-year and by showing how the Portfolio's average annual returns for the past one year period and since inception compare with those of a broad measure of market performance and a customized index, as well as an index that represents a group of similar mutual funds, over time.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone (800) 548-7786
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.morganstanley.com/im
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Portfolio's past performance, before and after taxes, is not necessarily an indication of how the Portfolio will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Annual Total Returns—Calendar Years
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

High Quarter

  

6/30/13

    

8.61

%

  

Low Quarter

  

6/30/15

    

–5.09

%

  
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel High Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2013
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.61%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Low Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.09%)
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads The Portfolio's returns in the table include the maximum applicable sales charge for Class A and assume you sold your shares at the end of each period (unless otherwise noted).
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate The after-tax returns shown in the table above are calculated using the historical highest individual federal marginal income tax rates during the period shown and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and after-tax returns are not relevant to investors who hold their Portfolio shares through tax deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns for the Portfolio's other Classes will vary from Class I shares' returns.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher After-tax returns may be higher than before-tax returns due to foreign tax credits and/or an assumed benefit from capital losses that would have been realized had Portfolio shares been sold at the end of the relevant periods, as applicable.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock

The after-tax returns shown in the table above are calculated using the historical highest individual federal marginal income tax rates during the period shown and do not reflect the impact of state and local taxes. After-tax returns for the Portfolio's other Classes will vary from Class I shares' returns. Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and after-tax returns are not relevant to investors who hold their Portfolio shares through tax deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns may be higher than before-tax returns due to foreign tax credits and/or an assumed benefit from capital losses that would have been realized had Portfolio shares been sold at the end of the relevant periods, as applicable.
Caption rr_AverageAnnualReturnCaption Average Annual Total Returns (for the calendar periods ended December 31, 2015)
Multi-Asset Portfolio | Bank of America/Merrill Lynch U.S. Dollar 1-Month LIBID Average Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 0.10% [1]
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 0.10% [1],[2]
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Jun. 22, 2012 [1]
Multi-Asset Portfolio | The Customized MSIM Global Allocation Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 (3.51%) [3]
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 5.25% [2],[3]
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Jun. 22, 2012 [3]
Multi-Asset Portfolio | Lipper Alternative Global Macro Funds Index (reflects no deductions for taxes)  
Risk/Return: rr_RiskReturnAbstract  
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 (4.22%) [4]
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 2.10% [2],[4]
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Jun. 22, 2012 [4]
Multi-Asset Portfolio | Class I  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption) rr_MaximumDeferredSalesChargeOverOther none
Advisory Fee rr_ManagementFeesOverAssets 0.85%
Distribution and/or Shareholder Service (12b-1) Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.29%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [5]
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 1.15% [6]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.05% [6]
Total Annual Portfolio Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.10% [6]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 360
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 628
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,393
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 112
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 360
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 628
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,393
Annual Return 2013 rr_AnnualReturn2013 18.24%
Annual Return 2014 rr_AnnualReturn2014 0.77%
Annual Return 2015 rr_AnnualReturn2015 (10.60%)
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 (10.60%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 3.09%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Jun. 22, 2012
Multi-Asset Portfolio | Class I | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 (11.01%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 2.13%
Multi-Asset Portfolio | Class I | After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 (5.81%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 2.06%
Multi-Asset Portfolio | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.25%
Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption) rr_MaximumDeferredSalesChargeOverOther none [7]
Advisory Fee rr_ManagementFeesOverAssets 0.85%
Distribution and/or Shareholder Service (12b-1) Fee rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.37%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [5]
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 1.48% [6]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.06% [6]
Total Annual Portfolio Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.42% [6]
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock Investments that are not subject to any sales charges at the time of purchase are subject to a contingent deferred sales charge ("CDSC") of 1.00% that will be imposed if you sell your shares within 18 months after the last day of the month of purchase, except for certain specific circumstances. See "Shareholder Information—How to Redeem Portfolio Shares" for further information about the CDSC waiver categories.
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts For purchases of Class A shares, you may qualify for a sales charge discount if the cumulative net asset value ("NAV") of Class A shares of the Portfolio purchased in a single transaction, together with the NAV of all Class A shares of other portfolios of Morgan Stanley Institutional Fund, Inc. (the "Fund") or Class A shares of other Morgan Stanley Multi-Class Funds (as defined in the section of this Prospectus entitled "Shareholder Information—Exchange Privilege") held in Related Accounts (as defined in the section of this Prospectus entitled "Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares"), amounts to $25,000 or more.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 25,000
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 662
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 963
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,285
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,196
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 662
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 963
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,285
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,196
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 (15.69%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 1.23%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Jun. 22, 2012
Multi-Asset Portfolio | Class L  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption) rr_MaximumDeferredSalesChargeOverOther none
Advisory Fee rr_ManagementFeesOverAssets 0.85%
Distribution and/or Shareholder Service (12b-1) Fee rr_DistributionAndService12b1FeesOverAssets 0.75%
Other Expenses rr_OtherExpensesOverAssets 0.32%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [5]
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 1.93% [6]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.03% [6]
Total Annual Portfolio Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.90% [6]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 193
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 603
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,039
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,251
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 193
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 603
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,039
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,251
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 (11.37%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 2.27%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Jun. 22, 2012
Multi-Asset Portfolio | Class C  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption) rr_MaximumDeferredSalesChargeOverOther 1.00% [8]
Advisory Fee rr_ManagementFeesOverAssets 0.85%
Distribution and/or Shareholder Service (12b-1) Fee rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.74%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [5]
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 2.60% [6]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.39% [6]
Total Annual Portfolio Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 2.21% [6]
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock The Class C CDSC is only applicable if you sell your shares within one year after purchase. See "Shareholder Information—How to Redeem Portfolio Shares" for a complete discussion of the CDSC.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 324
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 771
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,346
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,906
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 224
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 771
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,346
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,906
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Class C and Class IS shares of the Fund had not completed a full calendar year of operations as of December 31, 2015 and therefore Class C and Class IS shares do not have annualized return information to report.
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 [9]
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception [9]
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Apr. 30, 2015 [9]
Multi-Asset Portfolio | Class IS  
Risk/Return: rr_RiskReturnAbstract  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption) rr_MaximumDeferredSalesChargeOverOther none
Advisory Fee rr_ManagementFeesOverAssets 0.85%
Distribution and/or Shareholder Service (12b-1) Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 16.46%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [5]
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 17.32% [6]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets 16.24% [6]
Total Annual Portfolio Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.08% [6]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 110
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 3,280
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 5,717
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 9,621
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 110
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 3,280
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 5,717
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 9,621
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Class C and Class IS shares of the Fund had not completed a full calendar year of operations as of December 31, 2015 and therefore Class C and Class IS shares do not have annualized return information to report.
Average Annual Returns, Past One Year rr_AverageAnnualReturnYear01 [9]
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception [9]
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate May 29, 2015 [9]
[1] The Bank of America/Merrill Lynch U.S. Dollar 1-Month LIBID Average Index tracks the performance of a basket of synthetic assets paying LIBID to a stated maturity. The index purchases a new instrument each day, priced at par, having exactly its stated maturity and with a coupon equal to that day's fixing rate. All issues are held to maturity. Therefore, each day the index is comprised of a basket of securities. The index is not marked to market. The returns of the index represent the accrued income generated by the equally weighted average of all the coupons in the basket for a given day. It is not possible to invest directly in an index.
[2] Since Inception reflects the inception date of Class I.
[3] The Customized MSIM Global Allocation Index is comprised of 60% MSCI All Country World Index (benchmark that measures the equity market performance of developed and emerging markets), 30% Barclay Global Aggregate Bond Index (benchmark that provides a broad based measure of the global investment grade fixed-rate debt markets), 5% S&P GSCI Light Energy Index (benchmark for investment performance in the energy commodity market), and 5% Bank of America/Merrill Lynch U.S. Dollar 1-Month LIBID Average Index (benchmark that tracks the performance of a basket of synthetic assets paying LIBID to a stated maturity). It is not possible to invest directly in an index.
[4] The Lipper Alternative Global Macro Funds Index is an equally weighted performance index of the largest qualifying funds (based on net assets) in the Lipper Alternative Global Macro Funds classification. There are currently 30 funds represented in this Index.
[5] The Portfolio may invest a portion of its assets in other investment companies (the "Acquired Funds"). The Portfolio's shareholders indirectly bear a pro rata portion of the expenses of the Acquired Funds in which the Portfolio invests. "Acquired Fund Fees and Expenses" in the table is an estimate of those expenses. The estimate is based upon the average allocation of the Portfolio's investments in the Acquired Funds and upon the actual total operating expenses of the Acquired Funds (including any current waivers and expense limitations) for the fiscal year ended December 31, 2015. Actual Acquired Fund Fees and Expenses incurred by the Portfolio may vary with changes in the allocation of Portfolio assets among the Acquired Funds and with other events that directly affect the fees and expenses of the Acquired Funds. Since "Acquired Fund Fees and Expenses" are not directly borne by the Portfolio, they are not reflected in the Portfolio's financial statements, with the result that the information presented in the table will differ from that presented in the Financial Highlights.
[6] The Adviser has agreed to reduce its advisory fee and/or reimburse the Portfolio so that Total Annual Portfolio Operating Expenses, excluding Acquired Fund Fees and Expenses, certain investment related expenses, taxes, interest and other extraordinary expenses (including litigation), will not exceed 1.10% for Class I, 1.45% for Class A, 1.95% for Class L, 2.20% for Class C and 1.07% for Class IS. The fee waivers and/or expense reimbursements will continue for at least one year or until such time as the Fund's Board of Directors acts to discontinue all or a portion of such waivers and/or reimbursements when it deems such action is appropriate.
[7] Investments that are not subject to any sales charges at the time of purchase are subject to a contingent deferred sales charge ("CDSC") of 1.00% that will be imposed if you sell your shares within 18 months after the last day of the month of purchase, except for certain specific circumstances. See "Shareholder Information-How to Redeem Portfolio Shares" for further information about the CDSC waiver categories.
[8] The Class C CDSC is only applicable if you sell your shares within one year after purchase. See "Shareholder Information-How to Redeem Portfolio Shares" for a complete discussion of the CDSC.
[9] Class C and Class IS shares of the Fund had not completed a full calendar year of operations as of December 31, 2015 and therefore Class C and Class IS shares do not have annualized return information to report.