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Label Element Value
Lord Abbett Short Duration Tax Free Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Lord Abbett Short Duration Tax Free Fund
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The investment objective of the Fund is to seek the maximum amount of interest income exempt from federal income tax as is consistent with reasonable risk.
Expense [Heading] rr_ExpenseHeading FEES AND EXPENSES
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and certain members of your family invest, or agree to invest in the future, at least $100,000 in the Lord Abbett Family of Funds. More information about these and other discounts is available from your financial professional and in “Sales Charge Reductions and Waivers” on page 142 of the prospectus and “Purchases, Redemptions, Pricing, and Payments to Dealers” on page 8-1 of the statement of additional information (“SAI”).
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination Jan. 31, 2019
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover.
Portfolio Turnover [Text Block] 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 the 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 23.16% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 23.16%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge discounts if you and certain members of your family invest, or agree to invest in the future, at least $100,000 in the Lord Abbett Family of Funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 100,000
Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates Based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

This Example 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 for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same, giving effect to the fee waiver and expense reimbursement arrangement described above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption If Shares Are Redeemed
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If Shares Are Not Redeemed
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

In pursuing its investment objective, the Fund uses the volatility of the Barclays Municipal Bond Short 1-5 Year Index as an approximation of reasonable risk. To pursue its investment objective, under normal conditions, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in municipal bonds that pay interest exempt from federal income tax.


Under normal conditions, the Fund invests primarily in investment grade municipal bonds, which are bonds that are rated BBB/Baa or higher (at the time of purchase) by an independent rating agency or are unrated but deemed by Lord Abbett to be of comparable quality. The Fund may invest up to 20% of its net assets in municipal bonds rated BB/Ba or lower (at the time of purchase) by an independent rating agency or that are unrated but deemed by Lord Abbett to be of comparable quality (commonly referred to as “below investment grade,” “high yield,” or “junk” bonds).


The Fund may invest in all types of municipal bonds, including general obligation bonds, revenue bonds, municipal leases, and variable rate demand notes. Municipal bonds are debt securities issued by or on behalf of U.S. states, territories (such as Puerto Rico), and possessions and their political subdivisions, agencies, and instrumentalities that provide income that generally is exempt from federal, state, and/or local personal income tax. The Fund may invest in both insured and uninsured municipal bonds.


The Fund may invest up to 20% of its net assets in municipal bonds that pay interest that is subject to the federal alternative minimum tax (“AMT”), including certain private activity bonds (commonly referred to as “AMT paper”). Although the Fund is permitted to invest up to 20% of its net assets in fixed income securities that pay interest that is subject to federal, state, and local income tax, the Fund presently has no intention of investing in this manner. The Fund will not invest more than 25% of its total assets in any industry; however, this limitation does not apply to tax-exempt securities issued by governments or their agencies or instrumentalities. Certain types of municipal securities (including general obligation, general appropriation, municipal leases, special assessment, and special tax bonds) are not considered a part of any “industry” for purposes of this industry concentration policy. Therefore, the Fund may invest more than 25% of its total assets in these types of municipal securities. The Fund may invest without limitation in securities of issuers located in a single state, territory, municipality, or region.


The Fund may invest up to 15% of its net assets (measured at the time of investment) in illiquid securities.


The Fund may invest up to 20% of its assets in inverse floaters (also known as “residual interest bonds”), which are a type of derivative investment that provides leveraged exposure to underlying municipal bonds whose interest payments vary inversely with changes in short-term tax-exempt interest rates. These investments are intended to increase the Fund’s income and potential investment return. The Fund also may invest in other types of derivatives, such as futures, for non-hedging, hedging, or duration management purposes.


The maturity of a security measures the time until final payment is due, whereas duration takes into account the expected pattern of all payments of interest and principal on a security over time, including how these payments are affected by changes in interest rates. The Fund may invest in individual securities of any maturity or duration. Normally, the Fund seeks to maintain a dollar-weighted average maturity of between one and three years. Although the Fund may invest significantly in money market securities and their equivalents for investment purposes as well as for cash management purposes, it is not a money market fund and is not subject to the regulatory requirements applicable to money market funds.


The Fund’s investment team focuses on credit risk analysis, tax-exempt income yield, total return potential, interest rate risk, and call protection in managing its portfolio. The Fund generally will sell a security when the Fund believes the security is less likely to benefit from the current market and economic environment, shows signs of deteriorating fundamentals, or has reached its valuation target, among other reasons. The Fund seeks to remain fully invested in accordance with its investment objective. The Fund may, however, deviate entirely from the investment strategy described above for temporary defensive purposes. The Fund may miss certain investment opportunities if defensive strategies are used and thus may not achieve its investment objective.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Fund will not invest more than 25% of its total assets in any industry; however, this limitation does not apply to tax-exempt securities issued by governments or their agencies or instrumentalities.
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

As with any investment in a mutual fund, investing in the Fund involves risk, including the risk that you may receive little or no return on your investment. When you redeem your shares, they may be worth more or less than what you paid for them, which means that you may lose a portion or all of the money you invested in the Fund.


The following is a summary of certain risks that could adversely affect the Fund’s performance or increase volatility:


 

•

  

Portfolio Management Risk – If the strategies used and securities selected by the Fund’s portfolio management team fail to produce the intended result, the Fund may suffer losses or underperform other funds with the same investment objective or strategies, even in a rising market.
 

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Market Risk – The market values of securities will fluctuate, sometimes sharply and unpredictably, based on overall economic conditions, governmental actions or intervention, political developments, and other factors. Although prices of debt securities tend to rise and fall less dramatically than those of equity securities, they may experience heightened volatility.
 

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Fixed Income Securities Risk – The Fund is subject to the general risks and considerations associated with investing in debt securities, including the risk that issuers will fail to make timely payments of principal or interest or default altogether. Typically, shorter-term bonds are less volatile than longer-term bonds; however, longer-term bonds typically offer higher yields and more stable interest income than shorter-term bond investments. Lower rated municipal bonds in which the Fund may invest may be more volatile and may decline more in price in response to negative issuer developments or general economic news than higher rated securities. In addition, as interest rates rise, the Fund’s investments typically will lose value.
 

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Municipal Securities Risk – Municipal securities are subject to the same risks affecting fixed income securities in general. In addition, the price of municipal securities may be adversely affected by legislative or political changes, tax rulings, judicial action, changes in market and economic conditions, and the fiscal condition of the municipal issuer, including an insolvent municipality filing for bankruptcy. The Fund may be more sensitive to these events and conditions if it invests a substantial portion of its assets in the municipal securities of similar projects (such as those relating to education, health care, housing, transportation, and utilities) or in particular types of municipal securities (such as general obligation bonds, private activity bonds, and special tax bonds) or in the securities of issuers located within a single state, municipality, or geographic area. The market for municipal securities generally is less liquid than other securities markets, which may make it more difficult for the Fund to sell its municipal securities. Nongovernmental users of facilities financed by tax-exempt revenue bonds (e.g., companies in the electric utility and health care industries) may have difficulty making payments on their obligations in the event of an economic downturn. This would negatively affect the valuation of municipal securities issued by such facilities.
 

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Below Investment Grade Municipal Bond Risk – Below investment grade municipal bonds typically pay a higher yield than investment grade municipal bonds, but may have greater price fluctuations and have a higher risk of default than investment grade municipal bonds. The market for below investment grade municipal bonds may be less liquid due to such factors as specific municipal developments, interest rate sensitivity, negative perceptions of the junk bond markets generally, and less secondary market liquidity. This may make such bonds more difficult to sell at an acceptable price, especially during periods of financial distress, increased market volatility, or significant market decline.
 

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Call Risk – A substantial portion of municipal bonds are “callable,” meaning they give the issuer the right to call or redeem the bonds before maturity. As interest rates decline, these bond issuers may pay off their loans early by buying back the bonds, thus depriving the Fund of above market interest rates. Moreover, the Fund may not recoup the full amount of its initial investment and may have to reinvest the prepayment proceeds in lower yielding securities, securities with greater credit risks, or other less attractive securities.
 

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Credit Risk – Municipal bonds are subject to the risk that the issuer or guarantor of a security may not make interest and principal payments as they become due or may default altogether. In addition, if the market perceives a deterioration in the creditworthiness of an issuer, the value and liquidity of bonds issued by that issuer may decline. Credit risk varies based upon the economic and fiscal conditions of each issuer and the municipalities, agencies, instrumentalities, and other issuers within the state, territory, or possession. As noted above, to the extent that the Fund holds below investment grade securities, these risks may be heightened. Insured municipal bonds have the credit risk of the insurer in addition to the credit risk of the underlying investment being insured. A decline in the credit quality of private activity bonds usually is directly related to a decline in the credit standing of the private user of the facility.
 

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Derivatives Risk – Loss may result from the Fund’s investments in futures contracts, inverse floaters, and other derivative instruments. These instruments may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate and substantial losses to the Fund. They also may increase the Fund’s interest rate risk and may cause the Fund to realize a limited amount of taxable income. Losses also may arise from the failure of a derivative counterparty to meet its contractual obligations. Central clearing of derivatives is intended to decrease counterparty risk but does not make these transactions risk-free. In addition, the Fund will be required to “cover” its derivatives transactions in accordance with Securities and Exchange Commission guidance. This may include segregating permissible liquid assets to cover its obligations under these transactions and the Fund may have to liquidate positions before it is desirable to do so to fulfill its requirements to segregate. Whether the Fund’s use of derivatives is successful will depend on, among other things, the Fund’s ability to correctly forecast market movements and other factors. If the Fund incorrectly forecasts these and other factors, the Fund’s performance could suffer.
     

The Fund’s use of inverse floaters may reduce the Fund’s returns and/or increase the Fund’s volatility. Inverse floaters typically are more volatile than fixed rate municipal bonds. Distributions on inverse floaters are inversely related to short-term municipal bond interest rates. Therefore, distributions paid to the Fund on its inverse floaters will fall when short-term municipal interest rates rise and will rise when short-term municipal interest rates fall. Inverse floaters generally will underperform the market for fixed rate municipal bonds in a rising interest rate environment. Holders of inverse floaters bear the risk of the fluctuation in value of the issuing trust’s underlying municipal bonds because holders of the floaters have the right to tender their notes back to the trust for payment at par plus accrued interest. This creates effective leverage because the Fund’s net cash investment is significantly less than the value of the underlying bonds. The leverage ratio increases as the value of the inverse floaters becomes a greater proportion of the value of the municipal bonds deposited into the trust.
 

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Extension Risk – Rising interest rates may cause an issuer to pay off or retire a debt security later than expected, extending the duration of a bond, making them more sensitive to changes in interest rates. This typically will reduce the bond’s value, and cause the Fund to be unable to reinvest in higher yielding securities unless it is willing to incur a loss by selling its current holding.
 

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Governmental Risk – Government actions, including U.S. federal government actions and actions by local, state, and regional governments, could have an adverse effect on municipal bond prices. In addition, the Fund’s performance may be affected by local, state, and regional factors depending on the states in which the Fund’s investments are issued.
 

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Interest Rate Risk – As interest rates rise, prices of bonds (including tax-exempt bonds) generally fall, typically causing the Fund’s investments to lose value. Additionally, rising interest rates or lack of market participants may lead to decreased liquidity in the fixed income markets. Interest rate changes typically have a greater effect on the price of longer-term bonds, including inverse floaters, than on the price of shorter-term bonds. A wide variety of market factors can cause interest rates to rise, including central bank monetary policy, rising inflation, and changes in general economic conditions. The Fund will be exposed to heightened interest rate risk as interest rates rise from historically low levels.
 

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Liquidity/Redemption Risk – It may be difficult for the Fund to sell certain securities, including below investment grade municipal bonds, in a timely manner and at their stated value, which could result in losses to the Fund. In addition, the Fund may lose money when selling securities at inopportune times to fulfill shareholder redemption requests. The risk of loss may increase depending on the size and frequency of redemption requests, whether the redemption requests occur in times of overall market turmoil or declining prices, and whether the securities the Fund intends to sell have decreased in value or are illiquid. The Fund may be unable to sell illiquid securities at its desired time or price. As noted, the market for below investment grade municipal bonds generally is less liquid than the market for higher rated bonds, subjecting them to greater price fluctuations. The purchase price and subsequent valuation of illiquid securities normally reflect a discount, which may be significant, from the market price of comparable securities for which a liquid market exists. Illiquidity can be caused by a variety of factors, including economic conditions, market events, events relating to the issuer, a drop in overall market trading volume, an inability to find a ready buyer, or legal restrictions on the securities’ resale. Liquidity risk may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed income mutual funds may be higher than normal, causing increased supply in the market due to selling activity.
 

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Short Duration Risk – Although any rise in interest rates is likely to cause the prices of debt obligations to fall, the comparatively short duration of the Fund’s portfolio holdings is intended to mitigate some of this risk. The Fund generally will earn less income and, during periods of declining interest rates, will provide lower total returns to investors than funds with longer durations.
 

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State and Territory Risks – Although the Fund does not have a specific geographic focus, from time to time, to the extent the Fund invests in securities of issuers in a particular state, territory (such as Puerto Rico), municipality, or region, the Fund may be more exposed to risks affecting that particular state, territory, municipality, or region. As a result, adverse economic, political, and regulatory conditions affecting that state, territory, or region (and their political subdivisions, agencies, instrumentalities, and public authorities) are likely to affect the Fund’s performance.
 

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Taxability Risk – Although the Fund attempts to purchase only bona fide tax-exempt securities (except for its ability to invest up to 20% of its net assets in municipal bonds that pay interest subject to AMT and fixed income securities that pay interest that is subject to regular federal income tax), there is a risk that a bond issued as tax-exempt may be reclassified by the Internal Revenue Service (“IRS”) as taxable (for example, if the bond was issued in a transaction deemed by the IRS to be abusive), creating taxable rather than tax-exempt income. From time to time, proposals have been introduced before Congress for the purpose of restricting or eliminating the federal income tax exemption for interest on certain types of municipal bonds. Additionally, certain other proposals have been introduced that would have the effect of taxing a portion of exempt interest and/or reducing the tax benefits of receiving exempt interest. These legal uncertainties could affect the municipal bond market generally, certain specific segments of the market, or the relative credit quality of particular securities. Additionally, the Fund’s use of derivatives may increase the amount of distributions taxable to you as ordinary income, increase or decrease the amount of capital gain distributions to you and/or decrease the amount available for distribution to you as exempt-interest dividends.

An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. For more information on the principal risks of the Fund, please see the “More Information About the Funds – Principal Risks” section in the prospectus.
Risk Lose Money [Text] rr_RiskLoseMoney As with any investment in a mutual fund, investing in the Fund involves risk, including the risk that you may receive little or no return on your investment. When you redeem your shares, they may be worth more or less than what you paid for them, which means that you may lose a portion or all of the money you invested in the Fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund’s returns. Each assumes reinvestment of dividends and distributions. The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. No performance is shown for Class B shares because the Fund has not issued Class B shares to date. No performance is shown for Class T shares because this class has not completed a full calendar year of operations as of the date of this prospectus.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund’s returns.
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess No performance is shown for Class B shares because the Fund has not issued Class B shares to date. No performance is shown for Class T shares because this class has not completed a full calendar year of operations as of the date of this prospectus.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 888-522-2388
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.lordabbett.com
Performance Past Does Not Indicate Future [Text] 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.
Bar Chart [Heading] rr_BarChartHeading Bar Chart (per calendar year) — Class A Shares
Bar Chart Narrative [Text Block] rr_BarChartNarrativeTextBlock

The bar chart shows changes in the performance of the Fund’s Class A shares from calendar year to calendar year. This chart does not reflect the sales charge applicable to Class A shares. If the sales charge were reflected, returns would be lower. Performance for the Fund’s other share classes will vary due to the different expenses each class bears. Updated performance information is available at www.lordabbett.com or by calling 888-522-2388.
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads This chart does not reflect the sales charge applicable to Class A shares. If the sales charge were reflected, returns would be lower.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

 

 

 

Best Quarter 1st Q ’09 +2.36%

  

Worst Quarter 4th Q ’16 -1.77%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 2.36%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2016
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (1.77%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (for the periods ended December 31, 2016)
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads The Fund’s average annual total returns include applicable sales charges.
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate The after-tax returns of Class A shares included in the table below are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or Individual Retirement Accounts (“IRAs”).
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns for other share classes are not shown in the table and will vary from those shown for Class A shares.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In some cases, the return after taxes on distributions and sale of Fund shares may exceed the return before taxes due to a tax benefit resulting from realized losses on a sale of Fund shares at the end of the period that is used to offset other gains.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock

The table below shows how the Fund’s average annual total returns compare to the returns of a securities market index with investment characteristics similar to those of the Fund. The Fund’s average annual total returns include applicable sales charges.


The after-tax returns of Class A shares included in the table below are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. In some cases, the return after taxes on distributions and sale of Fund shares may exceed the return before taxes due to a tax benefit resulting from realized losses on a sale of Fund shares at the end of the period that is used to offset other gains. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or Individual Retirement Accounts (“IRAs”). After-tax returns for other share classes are not shown in the table and will vary from those shown for Class A shares.
Lord Abbett Short Duration Tax Free Fund | Bloomberg Barclays Municipal Bond Short 1-5 Year Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 0.07%
5 Years rr_AverageAnnualReturnYear05 1.09%
Life of Class rr_AverageAnnualReturnSinceInception 2.03%
Inception Date for Performance rr_AverageAnnualReturnInceptionDate Dec. 31, 2008
Lord Abbett Short Duration Tax Free Fund | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.25%
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none [1]
Management Fees rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.20%
Other Expenses rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.71%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.65% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 290
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 435
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 599
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,076
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 290
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 435
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 599
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,076
Annual Return 2009 rr_AnnualReturn2009 6.14%
Annual Return 2010 rr_AnnualReturn2010 2.17%
Annual Return 2011 rr_AnnualReturn2011 3.46%
Annual Return 2012 rr_AnnualReturn2012 2.16%
Annual Return 2013 rr_AnnualReturn2013 0.02%
Annual Return 2014 rr_AnnualReturn2014 1.58%
Annual Return 2015 rr_AnnualReturn2015 0.71%
Annual Return 2016 rr_AnnualReturn2016 (0.66%)
1 Year rr_AverageAnnualReturnYear01 (2.88%)
5 Years rr_AverageAnnualReturnYear05 0.30%
Life of Class rr_AverageAnnualReturnSinceInception 1.64%
Inception Date for Performance rr_AverageAnnualReturnInceptionDate Dec. 31, 2008
Lord Abbett Short Duration Tax Free Fund | Class A | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (2.88%)
5 Years rr_AverageAnnualReturnYear05 0.30%
Life of Class rr_AverageAnnualReturnSinceInception 1.63%
Lord Abbett Short Duration Tax Free Fund | Class A | After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (1.17%)
5 Years rr_AverageAnnualReturnYear05 0.52%
Life of Class rr_AverageAnnualReturnSinceInception 1.65%
Lord Abbett Short Duration Tax Free Fund | Class B  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther 5.00%
Management Fees rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.51%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.45% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 648
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 765
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,012
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,574
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 148
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 465
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 812
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,574
Lord Abbett Short Duration Tax Free Fund | Class C  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther 1.00% [3]
Management Fees rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.82% [4]
Other Expenses rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.33%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.27% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 229
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 409
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 717
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,591
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 129
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 409
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 717
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,591
1 Year rr_AverageAnnualReturnYear01 (2.25%)
5 Years rr_AverageAnnualReturnYear05 0.12%
Life of Class rr_AverageAnnualReturnSinceInception 1.23%
Inception Date for Performance rr_AverageAnnualReturnInceptionDate Dec. 31, 2008
Lord Abbett Short Duration Tax Free Fund | Class F  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none
Management Fees rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.10%
Other Expenses rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.61%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.55% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 56
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 183
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 328
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 750
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 56
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 183
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 328
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 750
1 Year rr_AverageAnnualReturnYear01 (0.56%)
5 Years rr_AverageAnnualReturnYear05 0.86%
Life of Class rr_AverageAnnualReturnSinceInception 2.03%
Inception Date for Performance rr_AverageAnnualReturnInceptionDate Dec. 31, 2008
Lord Abbett Short Duration Tax Free Fund | Class I  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none
Management Fees rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.51%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.45% [2]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 46
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 151
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 273
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 629
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 46
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 151
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 273
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 629
1 Year rr_AverageAnnualReturnYear01 (0.46%)
5 Years rr_AverageAnnualReturnYear05 0.95%
Life of Class rr_AverageAnnualReturnSinceInception 2.13%
Inception Date for Performance rr_AverageAnnualReturnInceptionDate Dec. 31, 2008
Lord Abbett Short Duration Tax Free Fund | Class T  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none
Management Fees rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.11% [5]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.76% [5]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2],[5]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.70% [2],[5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 320
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 475
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 650
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,157
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 320
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 475
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 650
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,157
[1] A contingent deferred sales charge ("CDSC") of 1.00% may be assessed on certain Class A shares purchased or acquired without a sales charge if they are redeemed before the first day of the month of the one-year anniversary of the purchase.
[2] For the period from February 1, 2017 through January 31, 2019, Lord, Abbett & Co. LLC has contractually agreed to waive its fees and reimburse expenses to the extent necessary to limit total net annual operating expenses, excluding 12b-1 fees, acquired fund's fees and expenses, and interest related expenses, to an annual rate of 0.45% for each class. This agreement may be terminated only by the Fund's Board of Directors.
[3] A CDSC of 1.00% may be assessed on Class C shares if they are redeemed before the first anniversary of their purchase.
[4] The 12b-1 fee the Fund will pay on Class C shares will be a blended rate calculated based on (i) 1.00% of the Fund's average daily net assets attributable to shares held for less than one year and (ii) 0.80% of the Fund's average daily net assets attributable to shares held for one year or more. All Class C shareholders of the Fund will bear 12b-1 fees at the same rate.
[5] Based on estimated amounts for the current fiscal year.