Objective, Primary [Text Block]

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Objective [Heading]

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Investment Objective

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The Senior Loan Portfolio (the "Fund") seeks a high level of current income.

Expense [Heading]

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Fees and Expenses

Expense Narrative [Text Block]

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The table below describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

For purchases of Class A shares, you may qualify for a sales charge discount if the cumulative net asset value per share ("NAV") of Class A shares of the Fund being purchased in a single transaction, together with the NAV of any Class A and Class C shares of the Fund already held in Related Accounts (as defined in the section of the Prospectus entitled "Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares") as of the date of the transaction as well as Class A, Class L and Class C shares of any other Morgan Stanley Multi-Class Fund excluding Morgan Stanley Institutional Fund Trust Short Duration Income, Ultra-Short Income and Ultra-Short Municipal Income Portfolios (as defined in the section of the Prospectus entitled "Shareholder Information—Exchange Privilege") and including shares of Morgan Stanley Money Market Funds (as defined in the section of the Prospectus entitled "Shareholder Information—Exchange Privilege") that you acquired in an exchange of Class A or Class C shares of the Fund or Class A, Class B, Class L or Class C shares of another Morgan Stanley Multi-Class Fund excluding Morgan Stanley Institutional Fund Trust Short Duration Income, Ultra-Short Income and Ultra-Short Municipal Income Portfolios already held in Related Accounts as of the date of the transaction, amounts to $100,000 or more. More information about this combined purchase discount and other discounts is available from your financial intermediary, on page 22 of the Prospectus in the section entitled "Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares" and in Appendix A attached to the Prospectus.

Class I shares may be available on brokerage platforms of firms that have agreements with the Fund's principal underwriter permitting such firms to (i) offer Class I shares solely when acting as an agent for the investor and (ii) impose on an investor transacting in Class I shares through such platforms a commission and/or other forms of compensation to the broker. Shares of the Fund are available in other share classes that have different fees and expenses.

Expense Breakpoint Discounts [Text]

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Expense Breakpoint, Minimum Investment Required [Amount]

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$ 100,000

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Other Expenses, New Fund, Based on Estimates [Text]

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Other Expenses have been estimated for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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

The example assumes that you invest $10,000 in the Fund, your investment has a 5% return each year and that the Fund'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]

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If You SOLD Your Shares

Expense Example, No Redemption, By Year, Caption [Text]

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If You HELD Your Shares

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund 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 Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. Because the Fund had not commenced operations as of the most recent fiscal year end, no portfolio turnover rate is available for the Fund.

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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Under normal circumstances, the Fund will invest at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in income-producing loans that hold a senior position in the capital structure of U.S. and foreign corporations (sometimes referred to as "Senior Loans") and derivatives and other senior debt instruments that effectively enable the Fund to achieve economic exposure similar to Senior Loans. The Fund intends to only purchase other senior debt instruments if such instruments are pari passu (i.e., on equal legal footing relative to other creditors) with other Senior Loans in the capital structure of a borrower with respect to collateral. These instruments will carry similar risks to Senior Loans.

Senior Loans are typically secured with specific collateral that is senior to subordinated debtholders and equity holders of the borrower. Senior Loans normally pay interest at rates that float above, or are adjusted periodically based on, a benchmark that reflects current interest rates.

Senior Loans are usually of below investment grade quality and have below investment grade credit ratings, which ratings are associated with securities having high risk, speculative characteristics (sometimes referred to as "high yield securities" or "junk"). High yield securities are fixed-income securities rated below Baa3 by Moody's Investors Service, Inc. ("Moody's"), below BBB- by S&P Global Ratings Group, a division of S&P Global Inc. ("S&P"), below BBB- by Fitch Ratings, Inc. ("Fitch") or, if unrated, considered by the Adviser to be of equivalent quality.

Senior Loans are loans made to borrowers that may be corporations, partnerships or other entities. These borrowers operate in a variety of industries and geographic regions, although most Senior Loans are made to borrowers that are organized or located in the U.S. Senior Loans generally are negotiated between a borrower and several financial institution lenders represented by one or more lenders acting as agent of all the lenders. The agent is responsible for negotiating the loan agreement that establishes the terms and conditions of the Senior Loan and the rights of the borrower and the lenders. The Fund may purchase assignments of portions of Senior Loans from third parties and may invest in participations in Senior Loans. Senior Loans also may take the form of debt obligations of borrowers issued directly to investors in the form of debt securities (i.e., Senior Notes). The Senior Loans in which the Fund invests may have varying degrees of restrictive covenants for lenders, including "covenant lite" loans.

The purchaser of an assignment typically succeeds to all the rights and obligations under the loan agreement of the assigning lender and becomes a lender under the loan agreement. Assignments may, however, be arranged through private negotiations, and the rights and obligations acquired by the purchaser of an assignment may differ from, and be more limited than, those held by the assigning lender.

When the Fund purchases a participation in a Senior Loan, the Fund will usually have a contractual relationship only with the lender selling the participation and not with the borrower. The Fund may have the right to receive payments of principal, interest and any fees to which it is entitled only from the lender selling the participation and only upon receipt by the lender of such payments from the borrower. As a result, the Fund may assume the credit risk of both the borrower and the lender selling the participation. In the event of insolvency of the lender selling a participation, the Fund may be treated as a general creditor of the lender.

The Fund may also invest in other types of derivatives, securities and cash equivalent instruments denominated in multiple currencies, as well as repurchase agreements and reverse repurchase agreements. The Fund may hold equity securities received as part of a reorganization or restructuring.

The Adviser's investment process starts with top-down macroeconomic analysis to assess the optimal positioning of the Fund. The Adviser then applies a combination of quantitative and qualitative filters to identify securities that meet the Fund's investment criteria in terms of competitive position, franchise value and management quality. The Adviser's credit analysis focuses on financial risk, business risk, management ability and intentions. Valuation analysis is used to narrow the screened investment universe to a pool of investment candidates, which are then assessed in order to determine relative valuation. Finally, the Fund's portfolio is constructed with sector allocation driven primarily from bottom-up security selection. Integral to the Fund's portfolio construction process is the measurement and monitoring of market risk, duration and volatility and credit risk through the use of proprietary risk measures and models.

The Fund's investment process incorporates information about environmental, social and governance issues (also referred to as ESG) via an integrated approach within the investment team's fundamental investment analysis framework. The Fund's Adviser may engage with management of certain issuers regarding corporate governance practices as well as what the Adviser deems to be materially important environmental and/or social issues facing a company.

The Fund has no requirements as to the range of maturities of the debt instruments it can buy or as to the market capitalization of the issuers of those instruments. The Fund may borrow money for investment purposes or to meet redemption requests.

The Fund 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 Fund's use of derivatives may involve the purchase and sale of derivative instruments such as futures, swaps and other related instruments and techniques. The Fund may utilize foreign currency forward exchange contracts, which are also derivatives, in connection with its investments in foreign securities. Derivative instruments used by the Fund will be counted towards the 80% policy discussed above to the extent they have economic characteristics similar to the securities included within that policy.

Risk [Heading]

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Principal Risks

Risk Narrative [Text Block]

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

Senior Loans. There are a number of risks associated with an investment in Senior Loans, including credit risk, interest rate risk, liquidity risk and prepayment risk. The Fund's investments in Senior Loans may be made in connection with highly leveraged transactions (i.e., transactions involving high levels of debt financing), including but not limited to, operating loans, leveraged buyout loans and leveraged capitalization loans. Senior Loans are also subject to the risk that a court could subordinate such Senior Loan, which typically holds a senior position in the capital structure of a borrower, to presently existing or future indebtedness or take other action detrimental to the holders of Senior Loans. In addition, Senior Loans are subject to the risk that the value of the collateral, if any, securing such Senior Loan may decline, be insufficient to meet the obligations of the borrower or be difficult to liquidate. In the event of a default, the Fund may have difficulty collecting on any collateral. The Fund may acquire and retain in its portfolio Senior Loans of borrowers that have filed for bankruptcy protection. In addition, the lenders' security interest or their enforcement of their security under the loan agreement may be found by a court to be invalid or the collateral may be used to pay other outstanding obligations of the borrower. The Fund's access to collateral, if any, may be limited by bankruptcy, other insolvency laws or by the type of Senior Loan the Fund has purchased. As a result, a collateralized Senior Loan may not be fully collateralized and can decline significantly in value. Uncollateralized Senior Loans involve a greater risk of loss.

Investments in Senior Loans may be limited. The limited availability may be due to a number of factors. There may be fewer Senior Loans available for investment that meet the Fund's credit standards, particularly in times of economic downturns. Also, lenders or agents may have an incentive to market the less desirable loans to investors such as the Fund while retaining attractive loans for themselves. This would reduce the amount of attractive investments for the Fund. If market demand for Senior Loans increases, the interest paid by such Senior Loans that the Fund holds may decrease.

Affiliates of the Adviser may participate in the primary and secondary market for loan obligations. Because of limitations imposed by applicable law, such activities may restrict the Fund's ability to acquire some loan obligations or affect the timing or price of such acquisitions. Also, because the Adviser may wish to invest in the publicly traded securities of a borrower, it may not have access to material non-public information regarding the borrower to which other lenders have access and thus may be at a material disadvantage in assessing the risk of loss.

In certain circumstances, Senior Loans may not be deemed to be securities, and in the event of fraud or misrepresentation, lenders will not have the protection of the anti-fraud provisions of the federal securities laws, as would be the case for bonds or stocks. Instead, in such cases, lenders generally rely on the contractual provisions in the loan agreement itself, and common-law fraud protections under applicable state law.

Credit and Interest Rate Risk. All fixed-income securities, such as Senior Loans, are subject to two types of risk: credit risk and interest rate risk. Credit risk refers to the possibility that the issuer or guarantor of a security will be unable to make interest payments and/or repay the principal on its debt. Interest rate risk refers to fluctuations in the value of a debt security resulting from changes in the general level of interest rates. 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. A low interest rate environment may prevent the Fund from providing a positive yield or paying Fund expenses out of Fund assets. The Fund may face a heightened level of interest rate risk in times of monetary policy change and uncertainty, such as when the Federal Reserve Board ends a quantitative easing program and/or has been raising rates. The value of Senior Loans can be affected by and can be sensitive to changes in government regulation and to economic downturns in the United States and abroad. Senior Loans generally are floating rate loans, which are subject to interest rate risk as the interest paid on the floating rate loans adjusts periodically based on changes in widely accepted reference rates. Furthermore, Senior Loan investments are often issued in connection with highly leveraged transactions. Such transactions include leveraged buyout loans, leveraged recapitalization loans and other types of acquisition financing. These obligations are subject to greater credit risks than other investments including a greater possibility that the borrower may default or enter bankruptcy. The risk of holding Senior Loans is also directly tied to the risk of insolvency or bankruptcy of the issuing banks. These risks could cause the Fund to lose income or principal on a particular investment, which in turn could affect the Fund's returns.

Liquidity Risk. The Fund may make investments that are illiquid or restricted or that may become less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. Liquidity risk may be magnified in a rising interest rate environment or in other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value. Due to restrictions on transfers in loan agreements and the nature of the private syndication of Senior Loans including, for example, the lack of publicly available information, some such Senior Loans are not as easily purchased or sold as publicly-traded securities. Lack of an active trading market, restrictions on resale, irregular trading activity, wide bid/ask spreads and extended trade settlement periods may impair the Fund's ability to sell Senior Loans within its desired time frame or at an acceptable price and its ability to accurately value existing and prospective investments. Extended trade settlement periods, which may be longer than seven days, may result in cash not being immediately available to the Fund. As a result, the Fund may have to sell other investments or engage in borrowing transactions to raise cash to meet its obligations. This extended settlement process can also (i) increase the counterparty credit risk borne by the Fund, (ii) leave the Fund unable to timely vote interests attached to the Senior Loans or otherwise act with respect to Senior Loans it has agreed to purchase, (iii) delay the Fund from realizing the proceeds of a sale of a Senior Loan, (iv) inhibit the Fund's ability to re-sell a Senior Loan that it has agreed to purchase if conditions change (leaving the Fund more exposed to price fluctuations), (v) prevent the Fund from timely collecting principal and interest payments and (vi) expose the Fund to adverse tax or regulatory consequences.

Prepayment Risk. Certain fixed-income securities, such as Senior Loans, are subject to the risk of unanticipated prepayment. Prepayment risk is the risk that, when interest rates fall, the issuer will redeem the security prior to the security's expected maturity, or that borrowers will repay the loans that underlie these fixed-income securities more quickly than expected, thereby causing the issuer of the security to repay the principal prior to expected maturity. The Fund may need to reinvest the proceeds at a lower interest rate, reducing its income. Securities subject to prepayment risk generally offer less potential for gains when prevailing interest rates fall. If the Fund buys those securities at a premium, accelerated prepayments on those securities could cause the Fund to lose a portion of its principal investment. The impact of prepayments on the price of a security may be difficult to predict and may increase the security's price volatility.

Covenant Lite Loans. Some of the Senior Loans in which the Fund may invest or obtain exposure to may be "covenant lite" loans. Certain financial institutions may define "covenant lite" loans differently. Covenant lite loans or securities, which have varied terms and conditions, may contain fewer or no restrictive covenants compared to other loans that might enable an investor to proactively enforce financial covenants or prevent undesired actions by the borrower. As a result, the Fund may experience relatively greater difficulty or delays in enforcing its rights on its holdings of certain covenant lite loans and debt securities than its holdings of loans or securities with more traditional financial covenants, which may result in losses to the Fund.

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 Fund may face a heightened level of interest rate risk in times of monetary policy change and uncertainty, such as when the Federal Reserve Board ends a quantitative easing program and/or has been raising rates. A rising interest rate environment increases certain risks, including the potential for periods of volatility and increased redemptions. The Fund may be subject to certain liquidity risks that 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. 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. To the extent that the Fund invests in convertible securities, and the convertible security's investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.

High Yield Securities. Senior Loans usually are of below investment grade quality and have below investment grade credit ratings, which ratings are associated with securities having high risk, speculative characteristics (sometimes referred to as "high yield securities" or "junk"). High yield securities offer a higher yield than other, higher rated securities, but they carry a greater degree of risk and are considered speculative by the major credit rating agencies. Changes in the value of high yield securities are influenced more by changes in the financial and business position of the issuing company than by changes in interest rates when compared to investment grade securities. Lower rated fixed-income securities have greater volatility because there is less certainty that principal and interest payments will be made as scheduled. Prices of fixed-income securities generally will move in correlation to changes in an issuer's credit rating and inversely to movements in interest rates. The Fund's investments in high yield securities expose it to a substantial degree of credit risk. Prices of high yield securities will rise and fall primarily in response to actual or perceived changes in the issuer's financial health, although changes in market interest rates also will affect prices. 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 Fund may incur additional expenses to seek recovery.

Repurchase Agreements. Repurchase agreements are transactions in which the Fund purchases a security or basket of securities and simultaneously commits to resell that security or basket to the seller (a bank, broker or dealer) at a mutually agreed-upon date and price. Repurchase agreements are subject to risks associated with the possibility of default by the seller at a time when the collateral has declined in value, or insolvency of the seller, which may affect the Fund's right to control the collateral and result in certain costs and delays. Repurchase agreements involving obligations other than U.S. government securities may be subject to special risks.

Reverse Repurchase Agreements. Under a reverse repurchase agreement, the Fund sells a security and promises to repurchase that security at an agreed-upon future date and price. Reverse repurchase agreements may be viewed as a speculative form of borrowing called leveraging. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet earmarking requirements. Leverage, including borrowing, may cause the Fund to be more volatile than if the Fund had not been leveraged. This is because leverage tends to exaggerate the effect of any increase or decrease in the value of the Fund's portfolio securities.

Financial Services. The Fund is more susceptible to any economic, business, political, regulatory or other developments that adversely affect issuers in the financial services sector. The Fund may invest without limit in instruments of the group of industries in the financial services sector, although the Fund will not concentrate its investments in issuers in any one industry. The profitability of many types of financial services companies may be adversely affected in certain market cycles, including periods of rising interest rates, which may restrict the availability and increase the cost of capital, and declining economic conditions, which may cause credit losses due to financial difficulties of borrowers. Financial services companies are also subject to extensive government regulation, including policy and legislative changes in the United States and other countries that are changing many aspects of financial regulation.

Foreign 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 that 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. In addition, the Fund's investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with 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 may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund'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.

Borrowing and Leverage. The Fund can borrow from banks, a technique referred to as "leverage," in amounts up to one-third of the Fund's total assets (including the amount borrowed) less all liabilities and indebtedness other than borrowings. The Fund can use those borrowings for investment-related purposes such as purchasing Senior Loans or other securities believed to be desirable by the Adviser when available. As long as the Fund is able to invest the proceeds of any financial leverage in Senior Loans or other investments that provide a higher net return than the current cost of such financial leverage and the Fund's operating expenses, the effect of leverage will be to cause Fund shareholders to realize a higher current rate of return than if the Fund were not leveraged. However, if the current costs of financial leverage were to exceed the return on such proceeds after expenses, Fund shareholders would have a lower rate of return than if the Fund had an unleveraged capital structure. The Fund may also borrow to meet redemption obligations or for temporary and emergency purposes. The Fund may participate in a line of credit with certain banks as lenders. Borrowing for leverage will subject the Fund to greater costs (for interest payments to the lenders and related expenses) than funds that do not borrow for leverage and these other purposes. The interest on borrowed money is an expense that might reduce the Fund's yield, especially if the cost of borrowing to buy investments exceeds the yield on the investments purchased with the proceeds of a loan. Using leverage may also make the Fund's share price more sensitive, i.e. volatile, than if the Fund did not use leverage due to the tendency to exaggerate the effect of any increase or decrease in the value of the Fund's portfolio investments. The use of leverage may also cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations to the lenders.

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.

Shares of the Fund 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]

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There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.

Risk Not Insured Depository Institution [Text]

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Shares of the Fund 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]

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Performance Information

Performance Narrative [Text Block]

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As of the date hereof, the Fund has not yet completed a full calendar year of investment operations. Upon the completion of a full calendar year of investment operations by the Fund, this section will include charts that provide some indication of the risks of an investment in the Fund, by showing the difference in annual total returns, highest and lowest quarterly returns and average annual total returns (before and after taxes) compared to a benchmark index selected for the Fund. Performance information for the Fund will be available online at www.morganstanley.com/im or by calling toll-free (800) 548-7786.

Performance Availability Website Address [Text]

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www.morganstanley.com/im

Performance Availability Phone [Text]

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(800) 548-7786

(MSIFT Senior Loan Portfolio) | Class I

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

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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

Distribution and/or Shareholder Service (12b-1) Fee

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.91%

^[1]

rr_ExpensesOverAssets

1.51%

^[2]

Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.71%

^[2]

rr_NetExpensesOverAssets

0.80%

^[2]

rr_ExpenseExampleYear01

$ 82

rr_ExpenseExampleYear03

407

rr_ExpenseExampleNoRedemptionYear01

(MSIFT Senior Loan Portfolio) | Class A

rr_ExpenseExampleNoRedemptionYear03

$ 407

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.25%

Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption)

rr_MaximumDeferredSalesChargeOverOther

none

^[3]

Distribution and/or Shareholder Service (12b-1) Fee

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.97%

^[1]

rr_ExpensesOverAssets

1.82%

^[2]

Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.67%

^[2]

rr_NetExpensesOverAssets

1.15%

^[2]

Expenses Deferred Charges [Text Block]

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Investments in Class A shares that are not subject to any sales charges at the time of purchase are subject to a contingent deferred sales charge ("CDSC") of 0.50% 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 Fund Shares" for further information about the CDSC waiver categories.

rr_ExpenseExampleYear01

$ 438

rr_ExpenseExampleYear03

816

rr_ExpenseExampleNoRedemptionYear01

438

(MSIFT Senior Loan Portfolio) | Class C

rr_ExpenseExampleNoRedemptionYear03

$ 816

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_ProspectusTable

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%

^[4]

Distribution and/or Shareholder Service (12b-1) Fee

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.97%

^[1]

rr_ExpensesOverAssets

2.57%

^[2]

Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.67%

^[2]

rr_NetExpensesOverAssets

1.90%

^[2]

Expenses Deferred Charges [Text Block]

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The Class C CDSC is only applicable if you sell your shares within one year after purchase. See "Shareholder Information—How To Redeem Fund Shares" for a complete discussion of the CDSC.

rr_ExpenseExampleYear01

$ 293

rr_ExpenseExampleYear03

736

rr_ExpenseExampleNoRedemptionYear01

193

(MSIFT Senior Loan Portfolio) | Class IS

rr_ExpenseExampleNoRedemptionYear03

$ 736

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_ProspectusTable

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

Distribution and/or Shareholder Service (12b-1) Fee

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.94%

^[1]

rr_ExpensesOverAssets

1.54%

^[2]

Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.79%

^[2]

rr_NetExpensesOverAssets

0.75%

^[2]

rr_ExpenseExampleYear01

$ 77

rr_ExpenseExampleYear03

409

rr_ExpenseExampleNoRedemptionYear01