rr_ProspectusTable

rr_ObjectiveHeading

Investment Objective

rr_ObjectivePrimaryTextBlock

The Core Plus Fixed Income Portfolio (the “Fund”) seeks above-average total return over a market cycle of three to five years.

rr_ExpenseHeading

Fees and Expenses

rr_ExpenseNarrativeTextBlock

The table below describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay fees other than the fees and expenses of the Fund, such as brokerage commissions and other fees charged by financial intermediaries, which are not reflected in the tables and examples below.

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, Class L 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, Class L or Class C shares of the Fund or Class A, 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 62 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, Minimum Investment Required [Amount]

rr_ExpenseBreakpointDiscounts

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

rr_OperatingExpensesCaption

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

rr_ExpenseExampleHeading

Example

rr_ExpenseExampleNarrativeTextBlock

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). After eight years, Class C shares of the Fund generally will convert automatically to Class A shares of the Fund. The example for Class C shares reflects the conversion to Class A shares after eight years. Please refer to the section of the Prospectus entitled “Shareholder Information—Conversion Features” for more information. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

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

rr_ExpenseExampleByYearCaption

If You SOLD Your Shares

rr_ExpenseExampleNoRedemptionByYearCaption

If You HELD Your Shares

rr_PortfolioTurnoverHeading

Portfolio Turnover

rr_PortfolioTurnoverTextBlock

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. During the most recent fiscal year, the Fund’s portfolio turnover rate was 434% of the average value of its portfolio.

rr_PortfolioTurnoverRate

434.00%

rr_StrategyHeading

Principal Investment Strategies

rr_StrategyNarrativeTextBlock

Under normal circumstances, at least 80% of the Fund’s assets will be invested in fixed-income securities. This policy may be changed without shareholder approval; however, you would be notified upon 60 days’ notice in writing of any changes. The Fund invests primarily in a diversified mix of U.S. dollar-denominated investment grade fixed-income securities, including U.S. government, corporate, municipal, mortgage- and asset-backed securities. The Fund will ordinarily seek to maintain an average weighted maturity between five and ten years.

The Adviser employs a value approach toward fixed-income investing and evaluates the relative attractiveness among corporate, mortgage and U.S. government securities, and also may invest in non-dollar-denominated issues. The Adviser relies upon value measures to guide its decisions regarding sector, security and country selection, such as the relative attractiveness of the extra yield offered by securities other than those issued by the U.S. Treasury. The Adviser also measures various types of risk by monitoring interest rates, inflation, the shape of the yield curve, credit risk, prepayment risk, country risk and currency valuations. The Fund may engage in frequent trading to achieve its investment objective.

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 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 may invest opportunistically in 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 by one or more rating agencies 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. The Fund may also invest in loan-related investments, such as public

bank loans made by banks or other financial institutions and loan participations and assignments, which may be rated investment grade or below investment grade. In addition, the Fund may invest in convertible securities.

The Fund’s mortgage securities may include collateralized mortgage obligations (“CMOs”), commercial mortgage-backed securities (“CMBS”), stripped mortgage-backed securities (“SMBS”) and inverse floating rate obligations (“inverse floaters”). In addition, the Fund may invest in to-be-announced pass-through mortgage securities, which settle on a delayed delivery basis (“TBAs”). The Fund may also invest in securities of foreign issuers, including issuers located in emerging market or developing countries. The securities in which the Fund may invest may be denominated in U.S. dollars or in currencies other than U.S. dollars. The Fund may also invest in restricted and illiquid securities.

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, options, 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 toward the Fund’s 80% policy discussed above to the extent they have economic characteristics similar to the securities included within that policy.

rr_RiskHeading

Principal Risks

rr_RiskNarrativeTextBlock

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:

•

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 and extension risk, which may vary depending on the type of asset.

•

Credit and Interest Rate Risk. Credit risk refers to the possibility that the issuer or guarantor of a security will be unable or unwilling or perceived to be unable to unwilling to make interest payments and/or repay the principal on its debt. In such instances, the value of the Fund could decline and the Fund could lose money. Interest rate risk refers to the decline in the value of a fixed-income 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. The Fund may invest in variable and floating rate loans and other variable and floating rate securities. Although these instruments are generally less sensitive to interest rate changes than fixed rate instruments, the value of variable and floating rate loans and other securities may decline if their interest rates do not rise as quickly, or as much, as general interest rates. The Fund may face a heightened level of interest rate risk in times of monetary policy change and/or uncertainty, such as when the Federal Reserve Board adjusts a quantitative easing program and/or changes rates. A changing interest rate environment increases certain risks, including the potential for periods of volatility, increased redemptions, shortened durations (i.e., prepayment risk) and extended durations (i.e., extension risk). During periods when interest rates are low or there are negative interest rates, the Fund’s yield (and total return) also may be low or otherwise adversely affected or the Fund may be unable to maintain positive returns. Credit ratings may not be an accurate assessment of liquidity or credit risk. Although credit quality may not accurately reflect the true credit risk of an instrument, a change in the credit rating of an instrument or an issuer can have a rapid, adverse effect on the instrument’s liquidity and make it more difficult for a Fund to sell at an advantageous price or time.

•

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 (i.e., interest rate risk), 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/or uncertainty, such as when the Federal Reserve Board adjusts a quantitative easing program and/or changes rates. A changing interest rate environment increases certain risks, including the potential for periods of volatility, increased redemptions, shortened durations (i.e., prepayment risk) and extended durations (i.e., extension risk). The Fund is not limited as to the maturities (when a debt security provides its final payment) or durations (measure of interest rate sensitivity) 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. A portion of the Fund’s fixed-income securities may be rated below investment grade. 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. 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.

•	Municipals. Because the Fund may invest in municipal securities (also referred to as municipal obligations), the Fund may be susceptible to political, legislative, economic, regulatory, tax or other factors affecting issuers of these municipal securities, such as

state and local governments and their agencies. To the extent that the Fund invests in municipal securities of issuers in the same economic sector, it could be more sensitive to economic, business or political developments that affect such sector. Municipal securities and their issuers may be more susceptible to downgrade, loss of revenue, default and bankruptcy because of recent periods of economic stress. Municipal securities also involve the risk that an issuer may call the securities for redemption, which could force the Fund to reinvest the proceeds at a lower rate of interest.

•

High Yield Securities (“Junk Bonds”). The Fund’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 are subject to greater risk of loss of income and principal than higher rated securities and may be considered speculative. 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.

•

Loan-Related Investments. In addition to risks generally associated with debt investments, loan-related investments, such as public bank loans and loan participations and assignments, are subject to other risks. Such investments may be subject to additional risks including subordination to other creditors, no collateral or limited rights in collateral, lack of a regular trading market, extended settlement periods, liquidity risks, prepayment risks, potentially less protection under the federal securities laws and lack of publicly available information. Bank loans are subject to the risk of default in the payment of interest or principal on a loan, which will result in a reduction of income to the Fund, and a potential decrease in the Fund’s NAV. The risk of default will increase in the event of an economic downturn or a substantial increase in interest rates. Because public bank loans usually rank lower in priority of payment to senior loans, they present a greater degree of investment risk. These bank loans may exhibit greater price volatility as well.

•

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 Fund’s yield, increase the volatility of the Fund 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, mortgage-backed securities are subject to credit risk. 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 Fund. The risk of such defaults is generally higher in the case of mortgage pools that include subprime mortgages. Furthermore, mortgage-backed securities may be subject to risks associated with the assets underlying those securities, such as a decline in value. Investments in mortgage-backed securities may give rise to a form of leverage (indebtedness) and may cause the Fund’s portfolio turnover rate to appear higher. Leverage may cause the Fund to be more volatile than if the Fund had not been leveraged. The risks associated with mortgage-backed securities typically become elevated during periods of distressed economic, market, health and labor conditions. In particular, increased levels of unemployment, delays and delinquencies in payments of mortgage and rent obligations, and uncertainty regarding the effects and extent of government intervention with respect to mortgage payments and other economic matters may adversely affect the Fund’s investments in mortgage-backed securities.

•

U.S. Government Securities. Different types of U.S. government securities are subject to different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. For example, a U.S. government-sponsored entity, such as Federal National Mortgage Association or Federal Home Loan Mortgage Corporation, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the U.S. Treasury and, therefore, are not backed by the full faith and credit of the United States. 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.

•

as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging markets countries. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. 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 due in accordance with the terms of such obligations. 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. 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. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities or groups of securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices.

•

Liquidity. 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 market where credit spread and interest rate volatility is rising and 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.

•

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 Fund’s exposure to currency exchange rates and could result in losses to the Fund 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 Fund’s securities are not denominated.

•

Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which may change due to economic and other events that affect markets generally, as well as those that affect particular regions, countries, industries, companies or governments. These events may be sudden and unexpected, and could adversely affect the liquidity of the Fund’s investments, which may in turn impact valuation, the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters, epidemics and pandemics, terrorism, conflicts and social unrest) adversely interrupt the global economy and financial markets. It is difficult to predict when events affecting the U.S. or global financial markets may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund.

•	Portfolio Turnover. Consistent with its investment policies, the Fund will purchase and sell securities without regard to the effect on portfolio turnover. Higher portfolio turnover will cause the Fund to incur additional transaction costs.

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.

rr_RiskLoseMoney

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

rr_RiskNotInsuredDepositoryInstitution

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.

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceNarrativeTextBlock

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s Class I shares’ performance from year-to-year and by showing how the Fund’s average annual returns for the past one, five and 10 year periods and since inception compare with those of a broad measure of market performance, 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 Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted). The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free 1-800-548-7786.

rr_PerformanceInformationIllustratesVariabilityOfReturns

rr_PerformanceAvailabilityPhone

1-800-548-7786

rr_PerformanceAvailabilityWebSiteAddress

www.morganstanley.com/im

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

rr_BarChartHeading

Annual Total Returns—Calendar Years

rr_PerformanceTableDoesReflectSalesLoads

The Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted).

rr_PerformanceTableUsesHighestFederalRate

Performance Table One Class of after Tax Shown [Text]

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 Fund shares through tax deferred arrangements such as 401(k) plans or individual retirement accounts.

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for the Fund’s other classes will vary from Class I shares’ returns.

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 Fund shares been sold at the end of the relevant periods, as applicable.

rr_BarChartClosingTextBlock

High Quarter

03/31/16

6.65%

Low Quarter

03/31/21

-2.81%

rr_PerformanceTableHeading

Average Annual Total Returns1(for the calendar periods ended December 31, 2021)

^[1]

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Bloomberg U.S. Aggregate Index (reflects no deduction for fees, expenses or taxes)

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 Fund’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 Fund 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 Fund shares been sold at the end of the relevant periods, as applicable.

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(1.54%)

^[2]

rr_AverageAnnualReturnYear05

3.57%

^[2]

rr_AverageAnnualReturnYear10

2.90%

^[2]

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Lipper Core Plus Bond Funds Index (reflects no deduction for taxes)

rr_AverageAnnualReturnSinceInception

6.63%

^[2],[3]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(0.39%)

^[4]

rr_AverageAnnualReturnYear05

4.26%

^[4]

rr_AverageAnnualReturnYear10

3.81%

^[4]

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Class I

rr_AverageAnnualReturnSinceInception

^[4]

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.37%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.25%

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

rr_ExpensesOverAssets

0.64%

^[5]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.20%

^[5]

rr_NetExpensesOverAssets

0.44%

^[5]

rr_ExpenseExampleYear01

$ 45

rr_ExpenseExampleYear03

185

rr_ExpenseExampleYear05

337

rr_ExpenseExampleYear10

779

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

185

rr_ExpenseExampleNoRedemptionYear05

337

rr_ExpenseExampleNoRedemptionYear10

$ 779

Annual Return 2012

rr_AnnualReturn2012

10.00%

rr_AnnualReturn2013

(0.23%)

rr_AnnualReturn2014

8.08%

rr_AnnualReturn2015

(0.30%)

rr_AnnualReturn2016

12.03%

rr_AnnualReturn2017

6.14%

rr_AnnualReturn2018

(0.43%)

rr_AnnualReturn2019

10.71%

rr_AnnualReturn2020

7.82%

rr_AnnualReturn2021

(0.45%)

rr_HighestQuarterlyReturnLabel

High Quarter

rr_BarChartHighestQuarterlyReturn

6.65%

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2016

rr_LowestQuarterlyReturnLabel

Low Quarter

rr_BarChartLowestQuarterlyReturn

(2.81%)

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2021

rr_AverageAnnualReturnYear01

(0.45%)

rr_AverageAnnualReturnYear05

4.66%

rr_AverageAnnualReturnYear10

5.22%

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Class I | Return After Taxes on Distributions

rr_AverageAnnualReturnSinceInception

6.96%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(1.44%)

^[6]

rr_AverageAnnualReturnYear05

3.23%

^[6]

rr_AverageAnnualReturnYear10

3.68%

^[6]

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Class I | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnSinceInception

4.47%

^[6]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(0.22%)

rr_AverageAnnualReturnYear05

2.98%

rr_AverageAnnualReturnYear10

3.38%

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Class A

rr_AverageAnnualReturnSinceInception

4.44%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.25%

rr_MaximumDeferredSalesChargeOverOther

none

^[7]

rr_ManagementFeesOverAssets

0.37%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.28%

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

rr_ExpensesOverAssets

0.92%

^[5]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.13%

^[5]

rr_NetExpensesOverAssets

0.79%

^[5]

rr_ExpensesDeferredChargesTextBlock

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

$ 403

rr_ExpenseExampleYear03

596

rr_ExpenseExampleYear05

805

rr_ExpenseExampleYear10

1,408

rr_ExpenseExampleNoRedemptionYear01

403

rr_ExpenseExampleNoRedemptionYear03

596

rr_ExpenseExampleNoRedemptionYear05

805

rr_ExpenseExampleNoRedemptionYear10

$ 1,408

rr_AverageAnnualReturnYear01

(4.05%)

rr_AverageAnnualReturnYear05

3.62%

rr_AverageAnnualReturnYear10

4.54%

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Class L

rr_AverageAnnualReturnSinceInception

4.61%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.37%

rr_DistributionAndService12b1FeesOverAssets

0.50%

rr_OtherExpensesOverAssets

0.40%

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

rr_ExpensesOverAssets

1.29%

^[5]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.25%

^[5]

rr_NetExpensesOverAssets

1.04%

^[5]

rr_ExpenseExampleYear01

$ 106

rr_ExpenseExampleYear03

384

rr_ExpenseExampleYear05

684

rr_ExpenseExampleYear10

1,535

rr_ExpenseExampleNoRedemptionYear01

106

rr_ExpenseExampleNoRedemptionYear03

384

rr_ExpenseExampleNoRedemptionYear05

684

rr_ExpenseExampleNoRedemptionYear10

$ 1,535

rr_AverageAnnualReturnYear01

(0.95%)

rr_AverageAnnualReturnYear05

4.03%

rr_AverageAnnualReturnYear10

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Class C

rr_AverageAnnualReturnSinceInception

4.37%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[8]

rr_ManagementFeesOverAssets

0.37%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.23%

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

rr_ExpensesOverAssets

1.62%

^[5]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[5]

rr_NetExpensesOverAssets

1.54%

^[5]

rr_ExpensesDeferredChargesTextBlock

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

rr_ExpenseExampleYear01

$ 257

rr_ExpenseExampleYear03

503

rr_ExpenseExampleYear05

874

rr_ExpenseExampleYear10

1,728

rr_ExpenseExampleNoRedemptionYear01

157

rr_ExpenseExampleNoRedemptionYear03

503

rr_ExpenseExampleNoRedemptionYear05

874

rr_ExpenseExampleNoRedemptionYear10

$ 1,728

rr_AverageAnnualReturnYear01

(2.37%)

rr_AverageAnnualReturnYear05

3.57%

rr_AverageAnnualReturnYear10

(MSIFT Fixed Income Portfolios) | (Core Plus Fixed Income Portfolio) | Class IS

rr_AverageAnnualReturnSinceInception

3.87%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.37%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.15%

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

rr_ExpensesOverAssets

0.54%

^[5]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.15%

^[5]

rr_NetExpensesOverAssets

0.39%

^[5]

rr_ExpenseExampleYear01

$ 40

rr_ExpenseExampleYear03

158

rr_ExpenseExampleYear05

287

rr_ExpenseExampleYear10

663

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

158

rr_ExpenseExampleNoRedemptionYear05

287

rr_ExpenseExampleNoRedemptionYear10

$ 663

rr_AverageAnnualReturnYear01

(0.40%)

rr_AverageAnnualReturnYear05

rr_AverageAnnualReturnYear10

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio)

rr_AverageAnnualReturnSinceInception

5.37%

rr_ProspectusTable

rr_ObjectiveHeading

Investment Objective

rr_ObjectivePrimaryTextBlock

The Corporate Bond Portfolio (the “Fund”) seeks above-average total return over a market cycle of three to five years.

rr_ExpenseHeading

Fees and Expenses

rr_ExpenseNarrativeTextBlock

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointDiscounts

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

rr_OperatingExpensesCaption

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

rr_ExpenseExampleHeading

Example

rr_ExpenseExampleNarrativeTextBlock

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.

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

rr_ExpenseExampleByYearCaption

If You SOLD Your Shares

rr_ExpenseExampleNoRedemptionByYearCaption

If You HELD Your Shares

rr_PortfolioTurnoverHeading

Portfolio Turnover

rr_PortfolioTurnoverTextBlock

rr_PortfolioTurnoverRate

125.00%

rr_StrategyHeading

Principal Investment Strategies

rr_StrategyNarrativeTextBlock

Under normal circumstances, at least 80% of the Fund’s assets will be invested in corporate bonds. This policy may be changed without shareholder approval; however, you would be notified upon 60 days’ notice in writing of any changes. The Fund invests primarily in a diversified mix of U.S. dollar-denominated corporate bonds. The Fund invests primarily in U.S. corporate bonds that carry an investment grade rating (i.e., generally rated Baa3 or higher by Moody’s Investors Service, Inc. (“Moody’s”), BBB- or higher by S&P Global Ratings Group, a division of S&P Global Inc. (“S&P”), BBB- or higher by Fitch Ratings, Inc. (“Fitch”)) or, if unrated, considered by the Adviser to be of equivalent quality. The Fund may also invest in securities denominated in currencies other than U.S. dollars.

The Adviser employs a value approach toward fixed-income investing and evaluates the relative attractiveness of corporate bonds. The Adviser relies upon value measures to guide its decisions regarding sector and security selection, such as the relative attractiveness of the extra yield offered by securities other than those issued by the U.S. Treasury. The Adviser also measures various types of risk by monitoring interest rates, inflation, the shape of the yield curve, credit risk and prepayment risk.

The Fund may also invest in restricted and illiquid securities.

counted towards the Fund’s 80% policy discussed above to the extent they have economic characteristics similar to the securities included within that policy.

rr_RiskHeading

Principal Risks

rr_RiskNarrativeTextBlock

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:

•

Foreign Currency. The Fund’s investments in foreign securities may be denominated in foreign currencies. The value of foreign currencies may fluctuate relative to the value of the U.S. dollar. Since the Fund may invest in such non-U.S. dollar-denominated securities, and therefore may convert the value of such securities into U.S. dollars, changes in currency exchange rates can increase or decrease the U.S. dollar value of the Fund’s assets. Currency exchange rates may fluctuate significantly over short periods of time for a number of reasons, including changes in interest rates and the overall economic health of the issuer. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. The Adviser may use derivatives to reduce this risk. The Adviser may in its discretion choose not to hedge against currency risk. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.

•

•	Portfolio Turnover. Consistent with its investment policies, the Fund will purchase and sell securities without regard to the effect on portfolio turnover. Higher portfolio turnover will cause the Fund to incur additional transaction costs.

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.

rr_RiskLoseMoney

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

rr_RiskNotInsuredDepositoryInstitution

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.

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceNarrativeTextBlock

rr_PerformanceInformationIllustratesVariabilityOfReturns

rr_PerformanceAvailabilityPhone

1-800-548-7786

rr_PerformanceAvailabilityWebSiteAddress

www.morganstanley.com/im

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

rr_BarChartHeading

Annual Total Returns—Calendar Years

rr_PerformanceTableDoesReflectSalesLoads

The Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted).

rr_PerformanceTableUsesHighestFederalRate

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableNotRelevantToTaxDeferred

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for the Fund’s other classes will vary from Class I shares’ returns.

rr_PerformanceTableExplanationAfterTaxHigher

rr_BarChartClosingTextBlock

High Quarter

06/30/20

10.05%

Low Quarter

03/31/21

-4.85%

rr_PerformanceTableHeading

Average Annual Total Returns1(for the calendar periods ended December 31, 2021)

^[9]

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Bloomberg U.S. Corporate Index (reflects no deduction for fees, expenses or taxes)

rr_PerformanceTableClosingTextBlock

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(1.04%)

^[10]

rr_AverageAnnualReturnYear05

5.26%

^[10]

rr_AverageAnnualReturnYear10

4.70%

^[10]

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Lipper Corporate Debt Funds BBB-Rated Index (reflects no deduction for taxes)

rr_AverageAnnualReturnSinceInception

6.68%

^[10],[11]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(0.81%)

^[12]

rr_AverageAnnualReturnYear05

5.25%

^[12]

rr_AverageAnnualReturnYear10

4.63%

^[12]

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Class I

rr_AverageAnnualReturnSinceInception

6.30%

^[11],[12]

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.38%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.41%

rr_ExpensesOverAssets

0.79%

^[13]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.09%

^[13]

rr_NetExpensesOverAssets

0.70%

^[13]

rr_ExpenseExampleYear01

$ 71

rr_ExpenseExampleYear03

242

rr_ExpenseExampleYear05

427

rr_ExpenseExampleYear10

964

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

242

rr_ExpenseExampleNoRedemptionYear05

427

rr_ExpenseExampleNoRedemptionYear10

$ 964

Annual Return 2012

rr_AnnualReturn2012

11.35%

rr_AnnualReturn2013

(0.24%)

rr_AnnualReturn2014

8.08%

rr_AnnualReturn2015

(2.11%)

rr_AnnualReturn2016

15.07%

rr_AnnualReturn2017

6.90%

rr_AnnualReturn2018

(3.87%)

rr_AnnualReturn2019

15.72%

rr_AnnualReturn2020

10.31%

rr_AnnualReturn2021

(1.93%)

rr_HighestQuarterlyReturnLabel

High Quarter

rr_BarChartHighestQuarterlyReturn

10.05%

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

rr_LowestQuarterlyReturnLabel

Low Quarter

rr_BarChartLowestQuarterlyReturn

(4.85%)

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2021

rr_AverageAnnualReturnYear01

(1.93%)

rr_AverageAnnualReturnYear05

5.17%

rr_AverageAnnualReturnYear10

5.69%

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Class I | Return After Taxes on Distributions

rr_AverageAnnualReturnSinceInception

6.28%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(3.31%)

^[14]

rr_AverageAnnualReturnYear05

3.68%

^[14]

rr_AverageAnnualReturnYear10

4.27%

^[14]

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Class I | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnSinceInception

4.21%

^[14]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(0.70%)

rr_AverageAnnualReturnYear05

3.43%

rr_AverageAnnualReturnYear10

3.87%

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Class A

rr_AverageAnnualReturnSinceInception

4.09%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.25%

rr_MaximumDeferredSalesChargeOverOther

none

^[15]

rr_ManagementFeesOverAssets

0.38%

rr_DistributionAndService12b1FeesOverAssets

0.25%

^[16]

rr_OtherExpensesOverAssets

0.39%

rr_ExpensesOverAssets

1.02%

^[13],[16]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.10%

^[13],[16]

rr_NetExpensesOverAssets

0.92%

^[13],[16]

rr_ExpensesDeferredChargesTextBlock

rr_ExpenseExampleYear01

$ 415

rr_ExpenseExampleYear03

628

rr_ExpenseExampleYear05

858

rr_ExpenseExampleYear10

1,518

rr_ExpenseExampleNoRedemptionYear01

415

rr_ExpenseExampleNoRedemptionYear03

628

rr_ExpenseExampleNoRedemptionYear05

858

rr_ExpenseExampleNoRedemptionYear10

$ 1,518

rr_AverageAnnualReturnYear01

(5.33%)

rr_AverageAnnualReturnYear05

4.16%

rr_AverageAnnualReturnYear10

5.06%

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Class L

rr_AverageAnnualReturnSinceInception

4.43%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.38%

rr_DistributionAndService12b1FeesOverAssets

0.50%

rr_OtherExpensesOverAssets

0.45%

rr_ExpensesOverAssets

1.33%

^[13]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[13]

rr_NetExpensesOverAssets

1.33%

^[13]

rr_ExpenseExampleYear01

$ 135

rr_ExpenseExampleYear03

420

rr_ExpenseExampleYear05

726

rr_ExpenseExampleYear10

1,596

rr_ExpenseExampleNoRedemptionYear01

135

rr_ExpenseExampleNoRedemptionYear03

420

rr_ExpenseExampleNoRedemptionYear05

726

rr_ExpenseExampleNoRedemptionYear10

$ 1,596

rr_AverageAnnualReturnYear01

(2.57%)

rr_AverageAnnualReturnYear05

4.46%

rr_AverageAnnualReturnYear10

5.03%

(MSIFT Fixed Income Portfolios) | (Corporate Bond Portfolio) | Class C

rr_AverageAnnualReturnSinceInception

4.81%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[17]

rr_ManagementFeesOverAssets

0.38%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.43%

rr_ExpensesOverAssets

1.81%

^[13]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[13]

rr_NetExpensesOverAssets

1.80%

^[13]

rr_ExpensesDeferredChargesTextBlock

rr_ExpenseExampleYear01

$ 282

rr_ExpenseExampleYear03

567

rr_ExpenseExampleYear05

976

rr_ExpenseExampleYear10

1,913

rr_ExpenseExampleNoRedemptionYear01

182

rr_ExpenseExampleNoRedemptionYear03

567

rr_ExpenseExampleNoRedemptionYear05

976

rr_ExpenseExampleNoRedemptionYear10

$ 1,913

rr_AverageAnnualReturnYear01

(3.98%)

rr_AverageAnnualReturnYear05

4.03%

rr_AverageAnnualReturnYear10

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio)

rr_AverageAnnualReturnSinceInception

4.35%

rr_ProspectusTable

rr_ObjectiveHeading

Investment Objective

rr_ObjectivePrimaryTextBlock

The High Yield Portfolio (the “Fund”) seeks total return.

rr_ExpenseHeading

Fees and Expenses

rr_ExpenseNarrativeTextBlock

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointDiscounts

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

rr_OperatingExpensesCaption

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

rr_ExpenseExampleHeading

Example

rr_ExpenseExampleNarrativeTextBlock

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.

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

rr_ExpenseExampleByYearCaption

If You SOLD Your Shares

rr_ExpenseExampleNoRedemptionByYearCaption

If You HELD Your Shares

rr_PortfolioTurnoverHeading

Portfolio Turnover

rr_PortfolioTurnoverTextBlock

rr_PortfolioTurnoverRate

54.00%

rr_StrategyHeading

Principal Investment Strategies

rr_StrategyNarrativeTextBlock

Under normal circumstances, at least 80% of the Fund’s assets will be invested in high yield securities (commonly referred to as “junk bonds”). This policy may be changed without shareholder approval; however, you would be notified upon 60 days’ notice in writing of any changes. The Fund seeks to achieve its investment objective by investing primarily in high yield securities which are fixed-income securities rated by one or more rating agencies 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. The average maturity of the Fund’s investments varies, and there is no limit on the maturity or on the credit quality of any security held by the Fund. The Fund’s securities may include distressed and defaulted securities and mezzanine investments. The Fund also may invest in investment grade fixed-income securities, including U.S. and foreign government securities, corporate bonds and collateralized bond obligations. The Fund may also invest in preferred securities, equity securities and convertible securities.

The Fund’s investment process starts with top-down macroeconomic analysis to assess the optimal positioning of the Fund. The team then applies a combination of quantitative and qualitative filters to identify securities that meet the team’s investment criteria in terms of competitive position, franchise value and management quality. The investment team’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 who are then assessed in order to determine relative valuation. Finally, the Fund is constructed with sector allocation driven primarily from bottom-up security selection. Integral to the Fund 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 may also invest in loan-related investments, such as public bank loans made by banks or other financial institutions and loan participations and assignments, which may be rated investment grade or below investment grade.

The Fund may also invest in restricted and illiquid securities.

rr_RiskHeading

Principal Risks

rr_RiskNarrativeTextBlock

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:

•

High Yield Securities (“Junk Bonds”). 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.

•

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, less stringent investor protections and disclosure standards, 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. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments, the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging markets countries. 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. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities or groups of securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices.

•

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. 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.

•

Preferred Securities. Preferred stock is issued with a fixed par value and pays dividends based on a percentage of that par value at a fixed rate. As with fixed-income securities, which also make fixed payments, the market value of preferred stock is sensitive to changes in interest rates. Preferred stock generally decreases in value if interest rates rise and increases in value if interest rates fall.

•

Mezzanine Investments. Mezzanine investments are subordinated debt securities that receive payments of interest and principal after other more senior security holders are paid. Mezzanine investments carry the risk that the issuer will not be able to meet its obligations and that the mezzanine investments may lose value.

•

Distressed and Defaulted Securities. Distressed and defaulted securities are speculative and involve substantial risks in addition to the risks of investing in high yield securities. The Fund will generally not receive interest payments on the distressed securities and the repayment of principal may also be at risk. These securities may present a substantial risk of default or may be in default at the time of investment, requiring the Fund to incur additional costs. The repayment of defaulted securities is also subject to significant uncertainties. The Fund may incur substantial expenses in seeking recovery upon a default in the payment of principal of or interest on its portfolio holdings.

•

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.

rr_RiskLoseMoney

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

rr_RiskNotInsuredDepositoryInstitution

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.

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceNarrativeTextBlock

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s Class I shares’ performance from year-to-year and by showing how the Fund’s average annual returns for the past one and five year periods and since inception compare with those of a broad measure of market performance, 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 Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted). The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free 1-800-548-7786.

rr_PerformanceInformationIllustratesVariabilityOfReturns

rr_PerformanceAvailabilityPhone

1-800-548-7786

rr_PerformanceAvailabilityWebSiteAddress

www.morganstanley.com/im

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

rr_BarChartHeading

Annual Total Returns—Calendar Years

rr_PerformanceTableDoesReflectSalesLoads

The Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted).

rr_PerformanceTableUsesHighestFederalRate

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableNotRelevantToTaxDeferred

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for the Fund’s other classes will vary from Class I shares’ returns.

rr_PerformanceTableExplanationAfterTaxHigher

rr_BarChartClosingTextBlock

High Quarter

06/30/20

10.05%

Low Quarter

03/31/20

-16.02%

rr_PerformanceTableHeading

Average Annual Total Returns(for the calendar periods ended December 31, 2021)

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Bloomberg U.S. Corporate High Yield Index (reflects no deduction for fees, expenses or taxes)

rr_PerformanceTableClosingTextBlock

rr_ProspectusTable

rr_AverageAnnualReturnYear01

5.28%

^[18]

rr_AverageAnnualReturnYear05

6.30%

^[18]

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Lipper High Current Yield Bond Funds Index (reflects no deduction for taxes)

rr_AverageAnnualReturnSinceInception

6.50%

^[18],[19]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

5.85%

^[20]

rr_AverageAnnualReturnYear05

5.76%

^[20]

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Class I

rr_AverageAnnualReturnSinceInception

5.86%

^[19],[20]

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.43%

rr_ExpensesOverAssets

1.03%

^[21]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.38%

^[21]

rr_NetExpensesOverAssets

0.65%

^[21]

rr_ExpenseExampleYear01

$ 66

rr_ExpenseExampleYear03

290

rr_ExpenseExampleYear05

532

rr_ExpenseExampleYear10

1,225

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

290

rr_ExpenseExampleNoRedemptionYear05

532

rr_ExpenseExampleNoRedemptionYear10

$ 1,225

rr_AnnualReturn2013

13.22%

rr_AnnualReturn2014

1.11%

rr_AnnualReturn2015

(1.71%)

rr_AnnualReturn2016

15.49%

rr_AnnualReturn2017

8.02%

rr_AnnualReturn2018

(2.20%)

rr_AnnualReturn2019

13.89%

rr_AnnualReturn2020

3.25%

rr_AnnualReturn2021

5.57%

rr_HighestQuarterlyReturnLabel

High Quarter

rr_BarChartHighestQuarterlyReturn

10.05%

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

rr_LowestQuarterlyReturnLabel

Low Quarter

rr_BarChartLowestQuarterlyReturn

(16.02%)

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2020

rr_AverageAnnualReturnYear01

5.57%

rr_AverageAnnualReturnYear05

5.57%

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Class I | Return After Taxes on Distributions

rr_AverageAnnualReturnSinceInception

7.13%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

3.22%

^[22]

rr_AverageAnnualReturnYear05

2.88%

^[22]

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Class I | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnSinceInception

3.93%

^[22]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

3.27%

rr_AverageAnnualReturnYear05

3.06%

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Class A

rr_AverageAnnualReturnSinceInception

4.05%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.25%

rr_MaximumDeferredSalesChargeOverOther

none

^[23]

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.42%

rr_ExpensesOverAssets

1.27%

^[21]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.27%

^[21]

rr_NetExpensesOverAssets

1.00%

^[21]

rr_ExpensesDeferredChargesTextBlock

rr_ExpenseExampleYear01

$ 424

rr_ExpenseExampleYear03

689

rr_ExpenseExampleYear05

974

rr_ExpenseExampleYear10

1,786

rr_ExpenseExampleNoRedemptionYear01

424

rr_ExpenseExampleNoRedemptionYear03

689

rr_ExpenseExampleNoRedemptionYear05

974

rr_ExpenseExampleNoRedemptionYear10

$ 1,786

rr_AverageAnnualReturnYear01

1.72%

rr_AverageAnnualReturnYear05

4.52%

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Class L

rr_AverageAnnualReturnSinceInception

6.40%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

0.50%

rr_OtherExpensesOverAssets

0.88%

rr_ExpensesOverAssets

1.98%

^[21]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.73%

^[21]

rr_NetExpensesOverAssets

1.25%

^[21]

rr_ExpenseExampleYear01

$ 127

rr_ExpenseExampleYear03

551

rr_ExpenseExampleYear05

1,000

rr_ExpenseExampleYear10

2,248

rr_ExpenseExampleNoRedemptionYear01

127

rr_ExpenseExampleNoRedemptionYear03

551

rr_ExpenseExampleNoRedemptionYear05

1,000

rr_ExpenseExampleNoRedemptionYear10

$ 2,248

rr_AverageAnnualReturnYear01

4.94%

rr_AverageAnnualReturnYear05

4.94%

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Class C

rr_AverageAnnualReturnSinceInception

6.50%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[24]

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.41%

rr_ExpensesOverAssets

2.01%

^[21]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.26%

^[21]

rr_NetExpensesOverAssets

1.75%

^[21]

rr_ExpensesDeferredChargesTextBlock

rr_ExpenseExampleYear01

$ 278

rr_ExpenseExampleYear03

605

rr_ExpenseExampleYear05

1,059

rr_ExpenseExampleYear10

2,126

rr_ExpenseExampleNoRedemptionYear01

178

rr_ExpenseExampleNoRedemptionYear03

605

rr_ExpenseExampleNoRedemptionYear05

1,059

rr_ExpenseExampleNoRedemptionYear10

$ 2,126

rr_AverageAnnualReturnYear01

3.43%

rr_AverageAnnualReturnYear05

4.45%

(MSIFT Fixed Income Portfolios) | (High Yield Portfolio) | Class IS

rr_AverageAnnualReturnSinceInception

4.22%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.60%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.34%

rr_ExpensesOverAssets

0.94%

^[21]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.32%

^[21]

rr_NetExpensesOverAssets

0.62%

^[21]

rr_ExpenseExampleYear01

$ 63

rr_ExpenseExampleYear03

268

rr_ExpenseExampleYear05

489

rr_ExpenseExampleYear10

1,125

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

268

rr_ExpenseExampleNoRedemptionYear05

489

rr_ExpenseExampleNoRedemptionYear10

$ 1,125

rr_AverageAnnualReturnYear01

5.69%

rr_AverageAnnualReturnYear05

5.62%

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio)

rr_AverageAnnualReturnSinceInception

4.90%

rr_ProspectusTable

rr_ObjectiveHeading

Investment Objective

rr_ObjectivePrimaryTextBlock

The Short Duration Income Portfolio (the “Fund”) seeks above-average total return over a market cycle of three to five years.

rr_ExpenseHeading

Fees and Expenses

rr_ExpenseNarrativeTextBlock

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointDiscounts

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

rr_OperatingExpensesCaption

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

rr_ExpenseExampleHeading

Example

rr_ExpenseExampleNarrativeTextBlock

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.

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

rr_ExpenseExampleByYearCaption

If You SOLD Your Shares

rr_ExpenseExampleNoRedemptionByYearCaption

If You HELD Your Shares

rr_PortfolioTurnoverHeading

Portfolio Turnover

rr_PortfolioTurnoverTextBlock

rr_PortfolioTurnoverRate

53.00%

rr_StrategyHeading

Principal Investment Strategies

rr_StrategyNarrativeTextBlock

Under normal market conditions, substantially all of the Fund’s assets will be invested in investment grade fixed-income securities denominated in U.S. dollars. This policy may be changed without shareholder approval; however, you would be notified in writing of any changes. The Fund invests primarily in U.S. government securities, investment grade corporate bonds and mortgage- and asset-backed securities. The Fund will ordinarily seek to maintain an average duration of approximately three years or less. With respect to corporate issuers, the Fund will not purchase securities with remaining maturities of more than 5.25 years.

The Adviser employs a value approach toward fixed-income investing and makes securities and sector decisions based on the anticipated tradeoff between long-run expected return and risk. The Fund seeks value in the fixed-income market with only a limited sensitivity to changes in interest rates. The Adviser relies upon value measures such as the level of real interest rates, yield curve slopes and credit-adjusted spreads to guide its decisions regarding interest rate, country, sector and security exposure. A team of portfolio managers implements strategies based on these types of value measures. Certain team members focus on specific bonds within each sector. Others seek to ensure that the aggregate risk exposures to changes in the level of interest rates and yield spreads match the Fund’s objective.

The Fund’s mortgage securities may include collateralized mortgage obligations (“CMOs”) and commercial mortgage-backed securities (“CMBS”). The Fund may also invest in asset-backed securities.

The Fund may invest in securities of foreign issuers, including issuers located in emerging market or developing countries, although only U.S. dollar denominated investment grade securities may be held in the Fund. The Fund may also invest in restricted and illiquid securities.

rr_RiskHeading

Principal Risks

rr_RiskNarrativeTextBlock

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:

•

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. The Fund may invest in variable and floating rate loans and other variable and floating rate securities. Although these instruments are generally less sensitive to interest rate changes than fixed rate instruments, the value of variable and floating rate loans and other securities may decline if their interest rates do not rise as quickly, or as much, as general interest rates. The Fund may face a heightened level of interest rate risk in times of monetary policy change and/or uncertainty, such as when the Federal Reserve Board adjusts a quantitative easing program and/or changes rates. A changing interest rate environment increases certain risks, including the potential for periods of volatility, increased redemptions, shortened durations (i.e., prepayment risk) and extended durations (i.e., extension risk). During periods when interest rates are low or there are negative interest rates, the Fund’s yield (and total return) also may be low or otherwise adversely affected or the Fund may be unable to maintain positive returns. Credit ratings may not be an accurate assessment of liquidity or credit risk. Although credit quality may not accurately reflect the true credit risk of an instrument, a change in the credit rating of an instrument or an issuer can have a rapid, adverse effect on the instrument’s liquidity and make it more difficult for a Fund to sell at an advantageous price or time.

•

capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging markets countries. 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. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities or groups of securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices.

•

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.

rr_RiskLoseMoney

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

rr_RiskNotInsuredDepositoryInstitution

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.

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceNarrativeTextBlock

after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free 1-800-548-7786.

rr_PerformanceInformationIllustratesVariabilityOfReturns

rr_PerformanceAvailabilityPhone

1-800-548-7786

rr_PerformanceAvailabilityWebSiteAddress

www.morganstanley.com/im

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

rr_BarChartHeading

Annual Total Returns—Calendar Years

rr_PerformanceTableDoesReflectSalesLoads

The Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted).

rr_PerformanceTableUsesHighestFederalRate

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableNotRelevantToTaxDeferred

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for the Fund’s other classes will vary from Class I shares’ returns.

rr_PerformanceTableExplanationAfterTaxHigher

rr_BarChartClosingTextBlock

High Quarter

06/30/20

5.14%

Low Quarter

03/31/20

-3.38%

rr_PerformanceTableHeading

Average Annual Total Returns1(for the calendar periods ended December 31, 2021)

^[25]

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Bloomberg 1-3 Year U.S. Government/Credit Index (reflects no deduction of fees, expenses or taxes)

rr_PerformanceTableClosingTextBlock

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(0.47%)

^[26]

rr_AverageAnnualReturnYear05

1.85%

^[26]

rr_AverageAnnualReturnYear10

1.39%

^[26]

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Short Duration Income Blend Index (reflects no deduction of fees, expenses or taxes)

rr_AverageAnnualReturnSinceInception

3.74%

^[26],[27]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(0.47%)

^[28]

rr_AverageAnnualReturnYear05

1.69%

^[28]

rr_AverageAnnualReturnYear10

1.26%

^[28]

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Lipper Short Investment Grade Debt Funds Index (reflects no deduction for taxes)

rr_AverageAnnualReturnSinceInception

3.70%

^[27],[28]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

0.11%

^[29]

rr_AverageAnnualReturnYear05

2.38%

^[29]

rr_AverageAnnualReturnYear10

2.00%

^[29]

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Class I

rr_AverageAnnualReturnSinceInception

3.64%

^[27],[29]

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.20%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.25%

rr_ExpensesOverAssets

0.45%

^[30]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.15%

^[30]

rr_NetExpensesOverAssets

0.30%

^[30]

rr_ExpenseExampleYear01

$ 31

rr_ExpenseExampleYear03

129

rr_ExpenseExampleYear05

237

rr_ExpenseExampleYear10

552

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

129

rr_ExpenseExampleNoRedemptionYear05

237

rr_ExpenseExampleNoRedemptionYear10

$ 552

Annual Return 2012

rr_AnnualReturn2012

3.33%

rr_AnnualReturn2013

1.40%

rr_AnnualReturn2014

1.37%

rr_AnnualReturn2015

(0.08%)

rr_AnnualReturn2016

8.37%

rr_AnnualReturn2017

1.94%

rr_AnnualReturn2018

2.11%

rr_AnnualReturn2019

4.07%

rr_AnnualReturn2020

3.40%

rr_AnnualReturn2021

0.01%

rr_HighestQuarterlyReturnLabel

High Quarter

rr_BarChartHighestQuarterlyReturn

5.14%

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

rr_LowestQuarterlyReturnLabel

Low Quarter

rr_BarChartLowestQuarterlyReturn

(3.38%)

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2020

rr_AverageAnnualReturnYear01

0.01%

rr_AverageAnnualReturnYear05

2.29%

rr_AverageAnnualReturnYear10

2.56%

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Class I | Return After Taxes on Distributions

rr_AverageAnnualReturnSinceInception

3.01%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(0.49%)

^[31]

rr_AverageAnnualReturnYear05

1.47%

^[31]

rr_AverageAnnualReturnYear10

1.80%

^[31]

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Class I | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnSinceInception

1.61%

^[31]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

none

rr_AverageAnnualReturnYear05

1.40%

rr_AverageAnnualReturnYear10

1.64%

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Class A

rr_AverageAnnualReturnSinceInception

1.75%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

2.00%

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.20%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.24%

rr_ExpensesOverAssets

0.69%

^[30]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.14%

^[30]

rr_NetExpensesOverAssets

0.55%

^[30]

rr_ExpenseExampleYear01

$ 255

rr_ExpenseExampleYear03

403

rr_ExpenseExampleYear05

563

rr_ExpenseExampleYear10

1,028

rr_ExpenseExampleNoRedemptionYear01

255

rr_ExpenseExampleNoRedemptionYear03

403

rr_ExpenseExampleNoRedemptionYear05

563

rr_ExpenseExampleNoRedemptionYear10

$ 1,028

rr_AverageAnnualReturnYear01

(2.11%)

rr_AverageAnnualReturnYear05

1.64%

rr_AverageAnnualReturnYear10

2.11%

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Class L

rr_AverageAnnualReturnSinceInception

0.49%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.20%

rr_DistributionAndService12b1FeesOverAssets

0.50%

rr_OtherExpensesOverAssets

0.47%

rr_ExpensesOverAssets

1.17%

^[30]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.37%

^[30]

rr_NetExpensesOverAssets

0.80%

^[30]

rr_ExpenseExampleYear01

$ 82

rr_ExpenseExampleYear03

335

rr_ExpenseExampleYear05

608

rr_ExpenseExampleYear10

1,387

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

335

rr_ExpenseExampleNoRedemptionYear05

608

rr_ExpenseExampleNoRedemptionYear10

$ 1,387

rr_AverageAnnualReturnYear01

(0.49%)

rr_AverageAnnualReturnYear05

1.78%

rr_AverageAnnualReturnYear10

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Class C

rr_AverageAnnualReturnSinceInception

1.90%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[32]

rr_ManagementFeesOverAssets

0.20%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.52%

rr_ExpensesOverAssets

1.72%

^[30]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.42%

^[30]

rr_NetExpensesOverAssets

1.30%

^[30]

rr_ExpensesDeferredChargesTextBlock

The Class C contingent deferred sales charge (“CDSC”) is only applicable if you sell your shares within one year after the last day of the month of purchase. See “Shareholder Information—How To Redeem Fund Shares” for a complete discussion of the CDSC.

rr_ExpenseExampleYear01

$ 232

rr_ExpenseExampleYear03

501

rr_ExpenseExampleYear05

894

rr_ExpenseExampleYear10

1,721

rr_ExpenseExampleNoRedemptionYear01

132

rr_ExpenseExampleNoRedemptionYear03

501

rr_ExpenseExampleNoRedemptionYear05

894

rr_ExpenseExampleNoRedemptionYear10

$ 1,721

rr_AverageAnnualReturnYear01

(1.92%)

rr_AverageAnnualReturnYear05

1.28%

rr_AverageAnnualReturnYear10

(MSIFT Fixed Income Portfolios) | (Short Duration Income Portfolio) | Class IS

rr_AverageAnnualReturnSinceInception

1.80%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.20%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

19.78%

rr_ExpensesOverAssets

19.98%

^[30]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

19.73%

^[30]

rr_NetExpensesOverAssets

0.25%

^[30]

rr_ExpenseExampleYear01

$ 26

rr_ExpenseExampleYear03

3,608

rr_ExpenseExampleYear05

6,197

rr_ExpenseExampleYear10

9,951

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

3,608

rr_ExpenseExampleNoRedemptionYear05

6,197

rr_ExpenseExampleNoRedemptionYear10

$ 9,951

rr_AverageAnnualReturnYear01

0.06%

rr_AverageAnnualReturnYear05

2.39%

rr_AverageAnnualReturnYear10

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio)

rr_AverageAnnualReturnSinceInception

3.34%

rr_ProspectusTable

rr_ObjectiveHeading

Investment Objective

rr_ObjectivePrimaryTextBlock

The Strategic Income Portfolio (the “Fund”) seeks to maximize current income consistent with the preservation of capital.

rr_ExpenseHeading

Fees and Expenses

rr_ExpenseNarrativeTextBlock

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 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 62 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.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointDiscounts

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 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.

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

rr_OperatingExpensesCaption

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

rr_ExpenseExampleHeading

Example

rr_ExpenseExampleNarrativeTextBlock

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.

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

rr_ExpenseExampleByYearCaption

If You SOLD Your Shares

rr_ExpenseExampleNoRedemptionByYearCaption

If You HELD Your Shares

rr_PortfolioTurnoverHeading

Portfolio Turnover

rr_PortfolioTurnoverTextBlock

rr_PortfolioTurnoverRate

38.00%

rr_StrategyHeading

Principal Investment Strategies

rr_StrategyNarrativeTextBlock

The Fund will primarily invest in fixed-income securities that the Adviser will allocate among asset classes or market segments and which include: (1) corporate securities, (2) residential and commercial mortgage-backed securities (“RMBS” and “CMBS”), (3) asset-backed securities, (4) foreign securities, including emerging market securities, and (5) U.S. government securities and foreign sovereign debt. The Fund may also invest in currency and other derivatives.

The Fund may invest up to 65% of its net assets in any one asset class or market segment. However, the amount of the Fund’s assets committed to any one asset class or market segment will fluctuate. The Adviser has the flexibility to select any combination of the aforementioned asset classes or market segments depending upon market conditions and the current economic environment and, as a result, at any given time the Fund’s assets may be invested in certain asset classes or market segments and not others. The Fund will invest at least 70% of its net assets in U.S. fixed-income securities and may have no more than 5% of net asset exposure to non-U.S. dollar currencies. The Fund will also invest at least 50% of its net assets in securities rated investment grade. The Fund may invest in securities of any duration; however, the average duration of the Fund will normally vary between zero and six years.

The Fund may invest in fixed-income securities issued or guaranteed by the U.S. Government, its agencies and instrumentalities or 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.

The Fund may invest in 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 non-investment grade by a nationally recognized statistical rating organization (“NRSRO”) or, if unrated, considered by the Adviser to be of equivalent quality. In the case of a security that is rated differently by rating agencies, the security will be treated as rated in the highest rating category.

The corporate securities in which the Fund will invest may include fixed-income securities issued by corporations located in or outside of the United States, certificates of deposit and bankers’ acceptances issued or guaranteed by, or time deposits maintained at, banks, commercial paper and convertible securities.

The Fund’s mortgage securities may include agency mortgage-backed securities that are guaranteed by the Federal National Mortgage Association (“Fannie Mae”) or the Federal Home Loan Mortgage Corporation (“Freddie Mac”), each a government-sponsored enterprise, or the Government National Mortgage Association (“Ginnie Mae”), non-agency RMBS, CMBS and various other asset-backed securities.

The Fund may invest in securities of foreign issuers, including issuers located in emerging market or developing countries. The Fund may make global, regional and sector allocations to foreign and emerging markets. The securities in which the Fund may invest may be denominated in U.S. dollars or in currencies other than U.S. dollars. The Fund may also invest in restricted and illiquid securities.

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, options, 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 toward the Fund’s exposure to the types of securities listed above to the extent they have economic characteristics similar to such securities.

The Adviser employs a value approach toward fixed-income investing. The Adviser relies upon value measures to guide its decisions regarding sector, security and country selection, such as the relative attractiveness of the extra yield offered by securities other than those issued by the U.S. Treasury. The Adviser also measures various types of risk by monitoring interest rates, inflation, the shape of the yield curve, credit risk, prepayment risk, country risk and currency valuations.

The Adviser may sell securities or exit positions when it believes that expected risk-adjusted return is low compared to other investment opportunities.

The Adviser believes that environmental, social and governance (“ESG”) factors have the ability to impact the fundamental credit risk of an entity and, in turn, the bond’s price. The Fund’s investment process incorporates information about ESG issues via an integrated approach within the Adviser’s fundamental investment analysis framework. The 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.

For corporate bonds, the Adviser has a proprietary ESG-scoring methodology that explicitly considers the risks and opportunities ESG factors pose to corporate bonds. By combining third-party ESG data with proprietary sector views, the Adviser creates a unique scoring methodology that it applies across issuers in the credit space.

From a sovereign perspective, ESG issues are considered within the framework of the Adviser’s fundamental country analysis and contribute to the Adviser’s view of a country.

Within securitized products, the Adviser’s consideration of ESG issues varies by underlying sector. For RMBS and asset-backed securities, the Adviser primarily focuses on the loan originators’ and servicers’ best practices. For CMBS, the focus is on the underlying commercial properties with particular emphasis on properties with potential environmental issues.

The Fund will not invest in the following:

•	Corporations that generate revenue from the manufacturing or production of tobacco;

•	Corporations that generate revenue from the manufacturing or production of landmines and cluster munitions (i.e., an explosive weapon that randomly scatters submunitions);

•	Corporations that generate revenue from the manufacturing or production of firearms;

•	Corporations that generate revenue from the mining of thermal coal or coal fired power generation; and

•	Corporations that primarily generate revenue from the fossil fuel industries, which the Adviser has determined produce a certain level of carbon emissions.

The Fund may invest in green bonds (a debt security that is typically issued to raise capital specifically to support climate-related or environmental projects) issued by companies that would otherwise be subject to fossil fuel exclusions so long as the Adviser has determined that the proceeds will not be used to finance fossil fuel generation capabilities.

In analyzing whether an issuer meets any of the criteria described above, the Adviser may rely upon, among other things, information provided by an independent third party.

rr_RiskHeading

Principal Risks

rr_RiskNarrativeTextBlock

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:

•

elevated during periods of distressed economic, market, health and labor conditions. In particular, increased levels of unemployment, delays and delinquencies in payments of mortgage and rent obligations, and uncertainty regarding the effects and extent of government intervention with respect to mortgage payments and other economic matters may adversely affect the Fund’s investments in mortgage-backed securities.

•

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, less stringent investor protections and disclosure standards, 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. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments, the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging markets countries. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. 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 due in accordance with the terms of such obligations. 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. 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. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities or groups of securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices.

•

•	Sovereign Debt Securities. Investing in sovereign debt securities will expose the Fund 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.

•

ESG Investment Risk. The Fund’s adherence to its ESG criteria and application of related analyses when selecting investments may affect the Fund’s performance depending on whether such investments are in or out of favor and relative to similar funds that do not adhere to such criteria or apply such analyses. Socially responsible norms differ by country and region, and a company’s ESG practices or the Adviser’s assessment of such may change over time. The Fund may invest in companies that do not reflect the beliefs and values of any particular investor. Additionally, the Fund’s adherence to its ESG criteria and application of related analyses in connection with identifying and selecting investments in non-U.S. issuers often require subjective analysis and may be relatively more difficult than applying the ESG criteria or related analyses to investments of U.S. issuers because data availability may be more limited with respect to non-U.S. issuers. The exclusionary criteria related to the Fund’s ESG criteria may result in the Fund forgoing opportunities to buy certain securities when it might otherwise be advantageous to do so, or selling securities for ESG reasons when it might be otherwise disadvantageous for it to do so. The Fund’s investments in certain companies may be susceptible to various factors that may impact their businesses or operations, including costs associated with government budgetary constraints that impact publicly funded projects and clean energy initiatives, the effects of general economic conditions throughout the world, increased competition from other providers of services, unfavorable tax laws or accounting policies and high leverage.

•

LIBOR Discontinuance or Unavailability Risk. The London InterBank Offered Rate (“LIBOR”) is intended to represent the rate at which contributing banks may obtain short-term borrowings from each other in the London interbank market. The regulatory authority that oversees financial services firms and financial markets in the U.K. has announced that, after the end of 2021, it would no longer persuade or compel contributing banks to make rate submissions for purposes of determining the LIBOR rate. However, subsequent announcements by the Financial Conduct Authority, the LIBOR administrator and other regulators indicate that it is possible that the most widely used tenors of U.S. Dollar LIBOR may continue to be provided on a representative basis until mid-2023. However, in connection with supervisory guidance from regulators, some regulated entities will cease to enter into most new LIBOR-based contracts after January 1, 2022. As a result, it is possible that commencing in 2022 (or on a later date, if a particular LIBOR tenor is expected to continue beyond the end of 2021), LIBOR may no longer be available or no longer deemed an appropriate reference rate upon which to determine the interest rate on or impacting certain loans, notes, derivatives and other instruments or investments comprising some or all of the Fund’s portfolio.

•

•	Portfolio Turnover. Consistent with its investment policies, the Fund will purchase and sell securities without regard to the effect on portfolio turnover. Higher portfolio turnover will cause the Fund to incur additional transaction costs.

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.

rr_RiskLoseMoney

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

rr_RiskNotInsuredDepositoryInstitution

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.

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceNarrativeTextBlock

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s Class I shares’ performance from year-to-year and by showing how the Fund’s average annual returns for the past one and five year periods and since inception compare with those of a broad measure of market performance, 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 Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted). The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free 1-800-548-7786.

rr_PerformanceInformationIllustratesVariabilityOfReturns

rr_PerformanceAvailabilityPhone

1-800-548-7786

rr_PerformanceAvailabilityWebSiteAddress

www.morganstanley.com/im

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

rr_BarChartHeading

Annual Total Returns—Calendar Years

rr_PerformanceTableDoesReflectSalesLoads

The Fund’s returns in the table include the maximum applicable sales charge for Class A and Class C and assume you sold your shares at the end of each period (unless otherwise noted).

rr_PerformanceTableUsesHighestFederalRate

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableNotRelevantToTaxDeferred

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for the Fund’s other classes will vary from Class I shares’ returns.

rr_PerformanceTableExplanationAfterTaxHigher

rr_BarChartClosingTextBlock

High Quarter

06/30/20

9.88%

Low Quarter

03/31/20

-12.27%

rr_PerformanceTableHeading

Average Annual Total Returns(for the calendar periods ended December 31, 2021)

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Bloomberg U.S. Aggregate Index (reflects no deduction for fees, expenses or taxes)

rr_PerformanceTableClosingTextBlock

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(1.54%)

^[33]

rr_AverageAnnualReturnYear05

3.57%

^[33]

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Strategic Income Blended Index (reflects no deduction for fees, expenses or taxes)

rr_AverageAnnualReturnSinceInception

3.01%

^[33],[34]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

(1.54%)

^[35]

rr_AverageAnnualReturnYear05

2.06%

^[35]

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Lipper Alternative Credit Focus Funds Index (reflects no deduction for taxes)

rr_AverageAnnualReturnSinceInception

1.52%

^[34],[35]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

2.44%

^[36]

rr_AverageAnnualReturnYear05

3.27%

^[36]

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Class I

rr_AverageAnnualReturnSinceInception

2.59%

^[34],[36]

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

1.04%

rr_ExpensesOverAssets

1.36%

^[37]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.76%

^[37]

rr_NetExpensesOverAssets

0.60%

^[37]

rr_ExpenseExampleYear01

$ 61

rr_ExpenseExampleYear03

356

rr_ExpenseExampleYear05

672

rr_ExpenseExampleYear10

1,569

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

356

rr_ExpenseExampleNoRedemptionYear05

672

rr_ExpenseExampleNoRedemptionYear10

$ 1,569

rr_AnnualReturn2015

(0.71%)

rr_AnnualReturn2016

3.92%

rr_AnnualReturn2017

7.17%

rr_AnnualReturn2018

0.94%

rr_AnnualReturn2019

6.49%

rr_AnnualReturn2020

2.79%

rr_AnnualReturn2021

1.87%

rr_HighestQuarterlyReturnLabel

High Quarter

rr_BarChartHighestQuarterlyReturn

9.88%

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

rr_LowestQuarterlyReturnLabel

Low Quarter

rr_BarChartLowestQuarterlyReturn

(12.27%)

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2020

rr_AverageAnnualReturnYear01

1.87%

rr_AverageAnnualReturnYear05

3.82%

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Class I | Return After Taxes on Distributions

rr_AverageAnnualReturnSinceInception

3.18%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

0.94%

^[38]

rr_AverageAnnualReturnYear05

2.55%

^[38]

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Class I | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnSinceInception

1.92%

^[38]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

1.10%

rr_AverageAnnualReturnYear05

2.41%

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Class A

rr_AverageAnnualReturnSinceInception

1.89%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.25%

rr_MaximumDeferredSalesChargeOverOther

none

^[39]

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

2.11%

rr_ExpensesOverAssets

2.68%

^[37]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.73%

^[37]

rr_NetExpensesOverAssets

0.95%

^[37]

rr_ExpensesDeferredChargesTextBlock

rr_ExpenseExampleYear01

$ 419

rr_ExpenseExampleYear03

971

rr_ExpenseExampleYear05

1,549

rr_ExpenseExampleYear10

3,116

rr_ExpenseExampleNoRedemptionYear01

419

rr_ExpenseExampleNoRedemptionYear03

971

rr_ExpenseExampleNoRedemptionYear05

1,549

rr_ExpenseExampleNoRedemptionYear10

$ 3,116

rr_AverageAnnualReturnYear01

(1.89%)

rr_AverageAnnualReturnYear05

2.76%

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Class C

rr_AverageAnnualReturnSinceInception

2.32%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[40]

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

1.90%

rr_ExpensesOverAssets

3.22%

^[37]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.52%

^[37]

rr_NetExpensesOverAssets

1.70%

^[37]

rr_ExpensesDeferredChargesTextBlock

rr_ExpenseExampleYear01

$ 273

rr_ExpenseExampleYear03

850

rr_ExpenseExampleYear05

1,551

rr_ExpenseExampleYear10

3,292

rr_ExpenseExampleNoRedemptionYear01

173

rr_ExpenseExampleNoRedemptionYear03

850

rr_ExpenseExampleNoRedemptionYear05

1,551

rr_ExpenseExampleNoRedemptionYear10

$ 3,292

rr_AverageAnnualReturnYear01

(0.23%)

rr_AverageAnnualReturnYear05

2.67%

(MSIFT Fixed Income Portfolios) | (Strategic Income Portfolio) | Class IS

rr_AverageAnnualReturnSinceInception

2.07%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

rr_MaximumDeferredSalesChargeOverOther

none

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

1.05%

rr_ExpensesOverAssets

1.37%

^[37]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.80%

^[37]

rr_NetExpensesOverAssets

0.57%

^[37]

rr_ExpenseExampleYear01

$ 58

rr_ExpenseExampleYear03

355

rr_ExpenseExampleYear05

673

rr_ExpenseExampleYear10

1,577

rr_ExpenseExampleNoRedemptionYear01

rr_ExpenseExampleNoRedemptionYear03

355

rr_ExpenseExampleNoRedemptionYear05

673

rr_ExpenseExampleNoRedemptionYear10

$ 1,577

rr_AverageAnnualReturnYear01

1.88%

rr_AverageAnnualReturnYear05

3.86%