XML 11 R9.htm IDEA: XBRL DOCUMENT v3.20.2
Label Element Value
Lord Abbett Micro-Cap Growth Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Lord Abbett Micro-Cap Growth Fund
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund’s investment objective is long-term capital appreciation.
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 $50,000 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 33 of the prospectus, Appendix A to the prospectus, titled “Intermediary-Specific Sales Charge Reductions and Waivers,” and “Purchases, Redemptions, Pricing, and Payments to Dealers” on page 9-1 of Part II 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 Feb. 28, 2022
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 94% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 94.00%
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 $50,000 in the Lord Abbett Family of Funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent These amounts have been updated from fiscal year amounts to reflect current fees and expenses.
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. Class C shares automatically convert to Class A shares after eight years. The expense example for Class C shares for the ten-year period reflects the conversion to Class A shares. 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

Under normal conditions, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in equity securities of micro-cap companies. A micro-cap company is defined as a company having a market capitalization at the time of purchase that is under $1 billion or falls within the market capitalization range of companies in the Russell Microcap® Index. The Fund uses fundamental analysis to look for micro-cap companies that appear to have the potential for more rapid growth than the overall economy. The Fund seeks to identify micro-cap companies that generally exhibit faster-than-average gains in earnings and that the portfolio management team expects to continue profit growth at a high level. The Fund evaluates companies based on an analysis of their financial statements, products and operations, market sectors, and interviews with management.


Equity securities in which the Fund may invest include common stocks, preferred stocks, equity interests in trusts (including real estate investment trusts and privately offered trusts), partnerships, joint ventures, limited liability companies and vehicles with similar legal structures, other instruments convertible or exercisable into the foregoing, and other investments with similar economic characteristics.


The Fund may invest up to 10% of its net assets in securities of foreign companies, including emerging market companies, American Depositary Receipts (“ADRs”), and other similar depositary receipts. In addition to ADRs, the Fund generally defines foreign companies as those whose securities are traded primarily on non-U.S. securities exchanges.


The Fund may engage in active and frequent trading of its portfolio securities.


The investment team may also consider the risks and return potential presented by environmental, social, and governance (ESG) factors in investment decisions. The Fund may sell a security when the Fund believes the security is less likely to benefit from the current market and economic environment, or shows signs of deteriorating fundamentals, among other reasons. The Fund may deviate 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.
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 principal risks of investing in the Fund, which could adversely affect its performance, include:


●Portfolio Management Risk: If the strategies used and investments 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 favorable market.

●Market Risk: The market values of securities will fluctuate, sometimes sharply and unpredictably, based on overall economic conditions, governmental actions or intervention, market disruptions caused by trade disputes or other factors, political developments, and other factors. Prices of equity securities tend to rise and fall more dramatically than those of debt securities.

●Equity Securities Risk: Equity securities, as well as equity-like securities such as convertible debt securities, may experience significant volatility. Such securities may fall sharply in response to adverse events affecting overall markets, a particular industry or sector, or an individual company’s financial condition.

●Industry and Sector Risk: Although the Fund does not employ an industry or sector focus, its exposure to specific industries or sectors will increase from time to time based on the portfolio management team’s perception of investment opportunities. If the Fund overweights a single industry or sector relative to its benchmark index, the Fund will face an increased risk that the value of its portfolio will decrease because of events disproportionately affecting that industry or sector. Furthermore, investments in particular industries or sectors may be more volatile than the broader market as a whole.

●Micro-Cap Company Risk: Investments in micro-cap companies may involve greater risks than investments in larger, more established companies. As compared to larger companies, micro-cap companies may have limited management experience or depth, limited ability to generate or borrow capital needed for growth, and limited products or services, or operate in less established markets. Accordingly, securities of micro-cap companies tend to be more sensitive to changing economic, market, and industry conditions and tend to be more volatile and less liquid than equity securities of larger companies, especially over the short term. The securities of micro-cap companies tend to trade less frequently than those of larger, more established companies, which can adversely affect the pricing of these securities and the ability to sell these securities in the future.
   
●Growth Investing Risk: Growth stocks typically trade at higher multiples of current earnings than other stocks. Growth stocks often are more sensitive to market fluctuations than other securities because their market prices are highly sensitive to future earnings expectations. At times when it appears that these expectations may not be met, prices of growth stocks typically fall. Growth stocks may be more volatile than securities of slower-growing issuers.

●Foreign and Emerging Market Company Risk: Investments in foreign companies and in U.S. companies with economic ties to foreign markets generally involve special risks that can increase the likelihood that the Fund will lose money. For example, as compared with companies organized and operated in the U.S., these companies may be more vulnerable to economic, political, and social instability and subject to less government supervision, lack of transparency, inadequate regulatory and accounting standards, and foreign taxes. In addition, the securities of foreign companies also may be subject to inadequate exchange control regulations, the imposition of economic sanctions or other government restrictions, higher transaction and other costs, reduced liquidity, and delays in settlement to the extent they are traded on non-U.S. exchanges or markets. Foreign company securities also include ADRs. ADRs may be less liquid than the underlying shares in their primary trading market. Foreign securities also may subject the Fund’s investments to changes in currency exchange rates. Emerging market securities generally are more volatile than other foreign securities, and are subject to greater liquidity, regulatory, and political risks. Investments in emerging markets may be considered speculative and generally are riskier than investments in more developed markets because such markets tend to develop unevenly and may never fully develop. Emerging markets are more likely to experience hyperinflation and currency devaluations. Securities of emerging market companies may have far lower trading volumes and less liquidity than securities of issuers in developed markets. Companies with economic ties to emerging markets may be susceptible to the same risks as companies organized in emerging markets.

●Liquidity/Redemption Risk: 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 less able to sell illiquid securities at its desired time or price. It may be more difficult for the Fund to value its investments in illiquid securities than more liquid securities.
   
●High Portfolio Turnover Risk: High portfolio turnover may result in increased transaction costs, reduced investment performance, and higher taxes resulting from increased realized capital gains, including short-term capital gains taxable as ordinary income when distributed to shareholders.

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 Fund – 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 [Text] rr_RiskNotInsured 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. Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have 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 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 class will vary due to the different expenses the 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 ’19 +22.67%

  

Worst Quarter 4th Q ’18 -23.39%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2019
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.67%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.39%)
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-advantaged 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 securities market indices 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-advantaged 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.
Average Annual Return, Caption rr_AverageAnnualReturnCaption Average Annual Total Returns (for the periods ended December 31, 2019)
Lord Abbett Micro-Cap Growth Fund | Russell MicroCap® Growth Index (reflects no deduction for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 23.33%
5 Years rr_AverageAnnualReturnYear05 4.87%
10 Years rr_AverageAnnualReturnYear10 10.69%
Lord Abbett Micro-Cap Growth Fund | Russell MicroCap® Index (reflects no deduction for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 22.43%
5 Years rr_AverageAnnualReturnYear05 6.57%
10 Years rr_AverageAnnualReturnYear10 11.26%
Lord Abbett Micro-Cap Growth Fund | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75% [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1],[2]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.31% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.31%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 701
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 966
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,252
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,063
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 701
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 966
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,252
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,063
Annual Return 2010 rr_AnnualReturn2010 33.77%
Annual Return 2011 rr_AnnualReturn2011 (5.87%)
Annual Return 2012 rr_AnnualReturn2012 2.35%
Annual Return 2013 rr_AnnualReturn2013 78.53%
Annual Return 2014 rr_AnnualReturn2014 10.83%
Annual Return 2015 rr_AnnualReturn2015 (6.38%)
Annual Return 2016 rr_AnnualReturn2016 2.07%
Annual Return 2017 rr_AnnualReturn2017 38.43%
Annual Return 2018 rr_AnnualReturn2018 2.74%
Annual Return 2019 rr_AnnualReturn2019 34.57%
1 Year rr_AverageAnnualReturnYear01 26.82%
5 Years rr_AverageAnnualReturnYear05 11.51%
10 Years rr_AverageAnnualReturnYear10 15.96%
Lord Abbett Micro-Cap Growth Fund | Class A | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 21.89%
5 Years rr_AverageAnnualReturnYear05 6.84%
10 Years rr_AverageAnnualReturnYear10 11.70%
Lord Abbett Micro-Cap Growth Fund | Class A | After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 18.85%
5 Years rr_AverageAnnualReturnYear05 7.83%
10 Years rr_AverageAnnualReturnYear10 11.78%
Lord Abbett Micro-Cap Growth Fund | Class C  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00% [1],[4]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.06% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 2.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 309
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 646
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,108
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,197
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 209
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 646
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,108
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,197
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
Lord Abbett Micro-Cap Growth Fund | Class F  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.10%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.16% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [5]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 353
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 624
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,395
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 108
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 353
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 624
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,395
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
Lord Abbett Micro-Cap Growth Fund | Class F3  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.15%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.05% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 334
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 579
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,283
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 107
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 334
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 579
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,283
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
Lord Abbett Micro-Cap Growth Fund | Class I  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.06% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 337
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 585
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,294
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 108
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 337
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 585
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,294
1 Year rr_AverageAnnualReturnYear01 34.56%
5 Years rr_AverageAnnualReturnYear05 12.84%
10 Years rr_AverageAnnualReturnYear10 16.74%
Lord Abbett Micro-Cap Growth Fund | Class R2  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.66% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 169
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 523
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 902
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,965
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 169
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 523
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 902
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,965
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
Lord Abbett Micro-Cap Growth Fund | Class R3  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.56% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.56%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 159
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 493
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 850
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,856
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 159
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 493
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 850
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,856
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
Lord Abbett Micro-Cap Growth Fund | Class R4  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.31% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.31%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 133
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 415
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 718
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,579
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 133
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 415
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 718
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,579
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
Lord Abbett Micro-Cap Growth Fund | Class R5  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.06% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 337
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 585
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,294
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 108
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 337
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 585
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,294
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
Lord Abbett Micro-Cap Growth Fund | Class R6  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [1]
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management Fees rr_ManagementFeesOverAssets 0.90%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.15%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.05% [3]
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets none
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 334
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 579
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,283
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 107
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 334
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 579
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,283
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance is not shown for Class C, F, F3, R2, R3, R4, R5 or R6 because these share classes have not completed a full calendar year of operations as of the date of this prospectus.
[1] A shareholder transacting in share classes without a front-end sales charge may be required to pay a commission to its financial intermediary. Please contact your financial intermediary for more information about whether such a commission may apply to your transaction.
[2] 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.
[3] These amounts have been updated from fiscal year amounts to reflect current fees and expenses.
[4] A CDSC of 1.00% may be assessed on Class C shares if they are redeemed before the first anniversary of their purchase.
[5] For the period from August 28, 2020 through February 28, 2022, Lord Abbett Distributor LLC ("Lord Abbett Distributor") has contractually agreed to waive the Fund's 0.10% Rule 12b-1 fee for Class F shares. This agreement may be terminated only by the Fund's Board of Trustees.