XML 14 R4.htm IDEA: XBRL DOCUMENT v3.20.1
Label Element Value
Prospectus [Line Items] rr_ProspectusLineItems  
Document Type dei_DocumentType 497
Document Period End Date dei_DocumentPeriodEndDate Dec. 31, 2019
Entity Registrant Name dei_EntityRegistrantName Needham Funds Inc
Entity Central Index Key dei_EntityCentralIndexKey 0001002537
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jun. 05, 2020
Document Effective Date dei_DocumentEffectiveDate Jun. 05, 2020
Prospectus Date rr_ProspectusDate May 01, 2020
Entity Inv Company Type dei_EntityInvCompanyType N-1A
Needham Aggressive Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Needham Aggressive Growth Fund
Supplement to Prospectus [Text Block] rr_SupplementToProspectusTextBlock
THE NEEDHAM FUNDS, INC.
Needham Aggressive Growth Fund

SUPPLEMENT DATED JUNE 5, 2020 TO THE SUMMARY PROSPECTUS
AND PROSPECTUS DATED MAY 1, 2020

Needham Investment Management L.L.C. (the “Adviser”) has entered into a new Fee Waiver and Expense Reimbursement Agreement under which the Adviser has agreed to waive its fee and, if necessary, reimburse the Needham Aggressive Growth Fund (the “Fund”) until April 30, 2021 to the extent Total Annual Fund Operating Expenses exceed 1.85% and 1.18% of the average daily net assets of Retail Class shares and Institutional Class shares, respectively, of the Fund (subject to certain exclusions).

Accordingly, effective as of June 1, 2020, the following replaces any contrary information contained in “Fees and Expenses of the Aggressive Growth Fund” in the Summary Prospectus and “Summary Section—Needham Aggressive Growth Fund—Fees and Expenses of the Aggressive Growth Fund” in the Prospectus:
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Aggressive Growth Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
This table describes the fees and expenses you may pay if you buy and hold shares of the Aggressive Growth Fund.
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 04/30/2021
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 Aggressive Growth Fund with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the Aggressive Growth Fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year, that all dividends and distributions have been reinvested, and that the Aggressive Growth Fund’s operating expenses remain the same (after giving effect to the fee waiver and expense reimbursement arrangement in year one only).
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Supplement Closing [Text Block] ck0001002537_SupplementClosingTextBlock
Please retain this Supplement with your Summary Prospectus and Prospectus for future reference.
Needham Aggressive Growth Fund | Retail Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol NEAGX
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.25%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Component2 Other Expenses rr_Component2OtherExpensesOverAssets 0.07%
Component3 Other Expenses rr_Component3OtherExpensesOverAssets 0.60%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.67%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 2.17%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.25%) [1]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 195
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 655
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,142
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,484
Needham Aggressive Growth Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol NEAIX
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.25%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Component2 Other Expenses rr_Component2OtherExpensesOverAssets 0.06%
Component3 Other Expenses rr_Component3OtherExpensesOverAssets 0.59%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.65%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.90%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.66%) [1]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.24%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 126
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 533
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 965
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,168
[1] Reflects a contractual agreement by Needham Investment Management LLC (the “Adviser”) to waive its fee and, if necessary, reimburse the Aggressive Growth Fund until April 30, 2021 to the extent Total Annual Fund Operating Expenses exceed 1.85% and 1.18% of the average daily net assets of Retail Class shares and Institutional Class shares, respectively, of the Aggressive Growth Fund (the “Expense Cap”). This agreement can only be amended or terminated by agreement of the Company, upon approval of the Company’s Board of Directors, and the Adviser and will terminate automatically in the event of termination of the Investment Advisory Agreement between the Adviser and the Company, on behalf of the Aggressive Growth Fund. For a period of up to 36 months from the time of any waiver or reimbursement pursuant to this agreement, the Adviser may recoup from the Aggressive Growth Fund fees waived and expenses reimbursed to the extent that such recovery would not cause the Total Annual Fund Operating Expenses of the Aggressive Growth Fund to exceed the lesser of the Expense Cap in effect (i) at the time of the waiver or reimbursement, or (ii) at the time of recoupment. Any such recovery will not include interest. The Expense Cap limitation on Total Annual Fund Operating Expenses excludes taxes, interest, brokerage, dividends on short positions, fees and expenses of “acquired funds” and extraordinary items but includes the management fee.