2.2.0.25truefalse010002 - Document - Delaware U.S. Growth Fund {Unlabeled}falsefalsetrue1falsefalseUSDtruefalse{dei_DocumentInformationDocumentAxis} : AAAA Member {dei_LegalEntityAxis} : S000003912 Member 4/15/2011 - 4/15/2011 USD ($) $c_S000003912_AAAAhttp://www.sec.gov/CIK0000910682duration2011-04-15T00:00:002011-04-15T00:00:00falsefalsedelaware_AAAAMemberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_AAAAMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedelaware_S000003912Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170RatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$1false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://delaware/role/aaaa1falsefalsefalse00Delaware U.S. Growth Fund | Delaware U.S. Growth FundDelaware U.S. Growth Fund | Delaware U.S. Growth Fundfalsefalsefalsefalsefalse1falsefalseUSDtruefalse{dei_DocumentInformationDocumentAxis} : AAAA Member {dei_LegalEntityAxis} : S000003912 Member 4/15/2011 - 4/15/2011 USD ($) $c_S000003912_AAAAhttp://www.sec.gov/CIK0000910682duration2011-04-15T00:00:002011-04-15T00:00:00falsefalsedelaware_AAAAMemberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_AAAAMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedelaware_S000003912Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170RatioStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseDelaware U.S. Growth Fund | Delaware U.S. Growth Fund3false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"><b> What is the Fund's investment objective? </b></p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective [Heading]4false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> Delaware U.S. Growth Fund seeks long-term capital appreciation by investing in equity securities of companies we believe have the potential for sustainable free cash flow growth. </p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective, Primary [Text Block]5false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"><b> What are the Fund's fees and expenses? </b></p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Fee Table Includes the following information, in plain English under rule 421(d) under the Securities Act, after Item 2 Fees and expenses of the Fund This table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Shareholder Fees (fees paid directly from your investment) Example 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 you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be You would pay the following expenses if you did not redeem your shares The Example does not reflect sales charges (loads) on reinvested dividends [and other distributions]. If these sales charges (loads) were included, your costs would be higher. Portfolio Turnover The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover may indicate higher transaction costs. These costs, which are not reflected in 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 __% of the average value of its whole portfolio. Instructions. A.3.instructions.6 New Funds. For purposes of this Item, a "New Fund" is a Fund that does not include in Form N-1A financial statements reporting operating results or that includes financial statements for the Fund's initial fiscal year reporting operating results for a period of 6 months or less. The following Instructions apply to New Funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph d -Subsection instructions falsefalseExpense [Heading]6false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> The following 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 your family invest, or agree to invest in the future, at least $50,000 in Delaware Investments® Funds. More information about these and other discounts is available from your financial advisor, in this prospectus under the section entitled "About your account," and in the Fund's statement of additional information under the section entitled "Purchasing shares." </p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThis table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown.The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Narrative [Text Block]7false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> Shareholder fees (fees paid directly from your investment) </p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringShareholder Fees (fees paid directly from your investment).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subsection table falsefalseShareholder Fees Caption [Text]8false0rr_ShareholderFeesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~http://delaware/role/ShareholderFeesDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsefalse<div style="display:none">~http://delaware/role/ShareholderFeesDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsehttp://delaware/role/ShareholderFeesDataAAAAfalsefalse020012 - Schedule - Shareholder Feestruefalsefalse1falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010961Memberrr_ProspectusShareClassAxisexplicitMemberClass AUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$2falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Brr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010962Memberrr_ProspectusShareClassAxisexplicitMemberClass BUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$3falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Crr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010963Memberrr_ProspectusShareClassAxisexplicitMemberClass CUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$4falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Rrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010964Memberrr_ProspectusShareClassAxisexplicitMemberClass RUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member3false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05750.0575falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalse3truetruetrue00falsefalsefalsetruefalse4truetruetrue00falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureMaximum Deferred Sales Charge (Load) (as a percentage of ____) A.3.instructions.2.a.i "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection table falsefalseMaximum sales charge (load) imposed on purchases as a percentage of offering pricefalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricetruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05750.0575falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalse3truetruetrue00falsefalsefalsetruefalse4truetruetrue00falsefalsefalsetruefalseOthernanafalsefalseMaximum sales charge (load) imposed on purchases as a percentage of offering price2falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member4false0rr_MaximumDeferredSalesChargeOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue00falsefalsefalsetruefalse2truetruetrue0.040.04[1]falsefalsefalsetruefalse3truetruetrue0.010.01[1]falsefalsefalsetruefalse4truetruetrue00falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureMaximum Deferred Sales Charge (Load) (as a percentage of ____) A.3.instructions.2.a.i "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph a -Clause i -Subsection instructions falsefalseMaximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lowerfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_MaximumDeferredSalesChargeOverOfferingPricetruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue00falsefalsefalsetruefalse2truetruetrue0.040.04[1]falsefalsefalsetruefalse3truetruetrue0.010.01[1]falsefalsefalsetruefalse4truetruetrue00falsefalsefalsetruefalseOthernanafalsefalseMaximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower1 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">If you redeem Class B shares during the first year after you buy them, you will pay a contingent deferred sales charge (CDSC) of 4.00%, which declines to 3.25% during the second year, 2.75% during the third year, 2.25% during the fourth and fifth years, 1.50% during the sixth year, and 0% thereafter. Class C shares redeemed within one year of purchase are subject to a 1.00% CDSC.</p> 42Shareholder Fees Delaware U.S. Growth FundUnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912MemberfalsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No authoritative reference available.falsefalseShareholder Fees [Table]9false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment) </p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 7 -Subsection table falsefalseOperating Expenses Caption [Text]10false0rr_AnnualFundOperatingExpensesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://delaware/role/OperatingExpensesDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsefalse<div style="display:none">~ http://delaware/role/OperatingExpensesDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsehttp://delaware/role/OperatingExpensesDataAAAAfalsefalse020022 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010961Memberrr_ProspectusShareClassAxisexplicitMemberClass AUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$2falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Brr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010962Memberrr_ProspectusShareClassAxisexplicitMemberClass BUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$3falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Crr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010963Memberrr_ProspectusShareClassAxisexplicitMemberClass CUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$4falseColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Rrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010964Memberrr_ProspectusShareClassAxisexplicitMemberClass RUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member3false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00640.0064falsefalsefalsetruefalse2truetruetrue0.00640.0064falsefalsefalsetruefalse3truetruetrue0.00640.0064falsefalsefalsetruefalse4truetruetrue0.00640.0064falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureManagement Fees include investment advisory fees (including any fees based on the Fund's performance), any other management fees payable to the investment adviser or its affiliates, and administrative fees payable to the investment adviser or its affiliates that are not included as "Other Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph a -Subsection instructions falsefalseManagement feesfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_ManagementFeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00640.0064falsefalsefalsetruefalse2truetruetrue0.00640.0064falsefalsefalsetruefalse3truetruetrue0.00640.0064falsefalsefalsetruefalse4truetruetrue0.00640.0064falsefalsefalsetruefalseOthernanafalsefalseManagement fees2falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member4false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.0030.003falsefalsefalsetruefalse2truetruetrue0.010.01falsefalsefalsetruefalse3truetruetrue0.010.01falsefalsefalsetruefalse4truetruetrue0.0060.006falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureDistribution [and/or Service] (12b-1) Fees" include all distribution or other expenses incurred during the most recent fiscal year under a plan adopted pursuant to rule 12b-1 [17 CFR 270.12b-1]. Under an appropriate caption or a subcaption of "Other Expenses," disclose the amount of any distribution or similar expenses deducted from the Fund's assets other than pursuant to a rule 12b-1 plan.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 9 -Subsection table falsefalseDistribution and service (12b-1) feesfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_DistributionAndService12b1FeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.0030.003falsefalsefalsetruefalse2truetruetrue0.010.01falsefalsefalsetruefalse3truetruetrue0.010.01falsefalsefalsetruefalse4truetruetrue0.0060.006falsefalsefalsetruefalseOthernanafalsefalseDistribution and service (12b-1) fees3falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member5false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruetrue0.00320.0032falsefalsefalsetruefalse2truetruetrue0.00320.0032falsefalsefalsetruefalse3truetruetrue0.00320.0032falsefalsefalsetruefalse4truetruetrue0.00320.0032falsefalsefalsetruefalseOtherrr:NonNegativePure4Typepure"Other Expenses" include all expenses not otherwise disclosed in the table that are deducted from the Fund's assets or charged to all shareholder accounts. The amount of expenses deducted from the Fund's assets are the amounts shown as expenses in the Fund's statement of operations (including increases resulting from complying with paragraph 2(g) of rule 6-07 of Regulation S-X [17 CFR 210.6-07]). "Other Expenses" do not include extraordinary expenses as determined under generally accepted accounting principles (see Accounting Principles Board Opinion No. 30). If extraordinary expenses were incurred that materially affected the Fund's "Other Expenses," disclose in a footnote to the table what "Other Expenses" would have been had the extraordinary expenses been included.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph c -Clause i -Subsection instructions truefalseOther expensesfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_OtherExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00320.0032falsefalsefalsetruefalse2truetruetrue0.00320.0032falsefalsefalsetruefalse3truetruetrue0.00320.0032falsefalsefalsetruefalse4truetruetrue0.00320.0032falsefalsefalsetruefalseOthernanafalsefalseOther expenses4falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member6false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruetrue0.01260.0126falsefalsefalsetruefalse2truetruetrue0.01960.0196falsefalsefalsetruefalse3truetruetrue0.01960.0196falsefalsefalsetruefalse4truetruetrue0.01560.0156falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses. If the Fund is a Feeder Fund, reflect the aggregate expenses of the Feeder Fund and the Master Fund in a single fee table using the captions provided. In a footnote to the fee table, state that the table and Example reflect the expenses of both the Feeder and Master Funds. If the prospectus offers more than one Class of a Multiple Class Fund or more than one Feeder Fund that invests in the same Master Fund, provide a separate response for each Class or Feeder Fund. Base the percentages of "Annual Fund Operating Expenses" on amounts incurred during the Fund's most recent fiscal year, but include in expenses amounts that would have been incurred absent expense reimbursement or fee waiver arrangements. If the Fund has changed its fiscal year and, as a result, the most recent fiscal year is less than three months, use the fiscal year prior to the most recent fiscal year as the basis for determining "Annual Fund Operating Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph d -Subsection instructions truefalseTotal annual fund operating expensesfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_ExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01260.0126falsefalsefalsetruefalse2truetruetrue0.01960.0196falsefalsefalsetruefalse3truetruetrue0.01960.0196falsefalsefalsetruefalse4truetruetrue0.01560.0156falsefalsefalsetruefalseOthernanafalsefalseTotal annual fund operating expenses5falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member7false0rr_FeeWaiverOrReimbursementOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue-0.0016-0.0016[1]falsefalsefalsetruefalse2truetruetrue-0.0011-0.0011[1]falsefalsefalsetruefalse3truetruetrue-0.0011-0.0011[1]falsefalsefalsetruefalse4truetruetrue-0.0021-0.0021[1]falsefalsefalsetruefalseOtherrr:NonPositivePure4TypepureTotal Annual Fund Operating Expenses. If there were expense reimbursement or fee waiver arrangements that reduced any Fund operating expenses and will continue to reduce them for no less than one year from the effective date of the Fund's registration statement, a Fund may add two captions to the table one caption showing the amount of the expense reimbursement or fee waiver, and a second caption showing the Fund's net expenses after subtracting the fee reimbursement or expense waiver from the total fund operating expenses. The Fund should place these additional captions directly below the "Total Annual Fund Operating Expenses" caption of the table and should use appropriate descriptive captions, such as "Fee Waiver [and/or Expense Reimbursement]" and "Total Annual Fund Operating Expenses After Fee Waiver [and/or Expense Reimbursement]," respectively. If the Fund provides this disclosure, also disclose the period for which the expense reimbursement or fee waiver arrangement is expected to continue, and briefly describe who can terminate the arrangement and under what circumstances.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table falsefalseFee waivers and expense reimbursementsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_FeeWaiverOrReimbursementOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse[1]1truetruetrue-0.0016-0.0016falsefalsefalsetruefalse2truetruetrue-0.0011-0.0011falsefalsefalsetruefalse3truetruetrue-0.0011-0.0011falsefalsefalsetruefalse4truetruetrue-0.0021-0.0021falsefalsefalsetruefalseOthernanafalsefalseFee waivers and expense reimbursements6falseRowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912Member8false0rr_NetExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruetrue0.0110.011falsefalsefalsetruefalse2truetruetrue0.01850.0185falsefalsefalsetruefalse3truetruetrue0.01850.0185falsefalsefalsetruefalse4truetruetrue0.01350.0135falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table truefalseTotal annual fund operating expenses after fee waivers and expense reimbursementsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth Fund0rr_NetExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.0110.011falsefalsefalsetruefalse2truetruetrue0.01850.0185falsefalsefalsetruefalse3truetruetrue0.01850.0185falsefalsefalsetruefalse4truetruetrue0.01350.0135falsefalsefalsetruefalseOthernanafalsefalseTotal annual fund operating expenses after fee waivers and expense reimbursements1 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">The Fund's investment manager, Delaware Management Company (Manager), has contractually agreed to waive all or a portion of its investment advisory fees and/or pay/reimburse expenses (excluding any 12b-1 plan, taxes, interest, inverse floater program expenses, short sale and dividend interest expenses, brokerage fees, certain insurance costs, and nonroutine expenses or costs, including, but not limited to, those relating to reorganizations, litigation, conducting shareholder meetings, and liquidations) in order to prevent total annual fund operating expenses from exceeding 0.85% of the Fund's average daily net assets from February 28, 2011 through February 28, 2012. The Fund's distributor, Delaware Distributors, L.P. (Distributor), has also contracted to limit the Fund's Class A and Class R shares' 12b-1 fees from February 28, 2011 through February 28, 2012 to no more than 0.25% and 0.50% of average daily net assets, respectively. These waivers and reimbursements may be terminated only by agreement of the Manager or Distributor, as applicable, and the Fund.</p> 46Annual Fund Operating Expenses Delaware U.S. Growth FundUnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*Rowdei_LegalEntityAxisAxisdelaware_S000003912MemberfalsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No authoritative reference available.falsefalseAnnual Fund Operating Expenses [Table]11false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"><b> Example </b></p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalseExpense Example [Heading]12false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">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 reflects the applicable waivers and reimbursements for the 1-year contractual period and the total operating expenses without waivers for years 2 through 10. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThe Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection example falsefalseExpense Example Narrative [Text Block]13false0rr_ExpenseExampleWithRedemptionTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://delaware/role/ExpenseExampleAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsefalse<div style="display:none">~ http://delaware/role/ExpenseExampleAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>truehttp://delaware/role/ExpenseExampleAAAAfalsefalse020032 - Schedule - Expense Example {Transposed}truefalsefalse1falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member3false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue678678falsefalsefalsetruefalse2truefalsetrue585585falsefalsefalsetruefalse3truefalsetrue285285falsefalsefalsetruefalse4truefalsetrue134134falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalse1 YearfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$2falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member4false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue934934falsefalsefalsetruefalse2truefalsetrue877877falsefalsefalsetruefalse3truefalsetrue602602falsefalsefalsetruefalse4truefalsetrue469469falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse3 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$3falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member5false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue12101210falsefalsefalsetruefalse2truefalsetrue12691269falsefalsefalsetruefalse3truefalsetrue10441044falsefalsefalsetruefalse4truefalsetrue827827falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse5 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$4falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member6false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue19941994falsefalsefalsetruefalse2truefalsetrue20922092falsefalsefalsetruefalse3truefalsetrue22742274falsefalsefalsetruefalse4truefalsetrue18361836falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse10 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$1falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010961Memberrr_ProspectusShareClassAxisexplicitMemberClass AUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue678678falsefalsefalsetruefalse2truefalsetrue934934falsefalsefalsetruefalse3truefalsetrue12101210falsefalsefalsetruefalse4truefalsetrue19941994falsefalsefalsetruefalseOthernanafalsefalseClass A2falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Brr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010962Memberrr_ProspectusShareClassAxisexplicitMemberClass BUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue585585falsefalsefalsetruefalse2truefalsetrue877877falsefalsefalsetruefalse3truefalsetrue12691269falsefalsefalsetruefalse4truefalsetrue20922092falsefalsefalsetruefalseOthernanafalsefalseClass B3falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Crr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010963Memberrr_ProspectusShareClassAxisexplicitMemberClass CUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue285285falsefalsefalsetruefalse2truefalsetrue602602falsefalsefalsetruefalse3truefalsetrue10441044falsefalsefalsetruefalse4truefalsetrue22742274falsefalsefalsetruefalseOthernanafalsefalseClass C4falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Rrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010964Memberrr_ProspectusShareClassAxisexplicitMemberClass RUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue134134falsefalsefalsetruefalse2truefalsetrue469469falsefalsefalsetruefalse3truefalsetrue827827falsefalsefalsetruefalse4truefalsetrue18361836falsefalsefalsetruefalseOthernanafalsefalseClass R44Expense Example Delaware U.S. Growth Fund (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912MemberRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExample.No authoritative reference available.falsefalseExpense Example, With Redemption [Table]14false0rr_ExpenseExampleNoRedemptionTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://delaware/role/ExpenseExampleNoRedemptionAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsefalse<div style="display:none">~ http://delaware/role/ExpenseExampleNoRedemptionAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>truehttp://delaware/role/ExpenseExampleNoRedemptionAAAAfalsefalse020042 - Schedule - Expense Example, No Redemption {Transposed}truefalsefalse1falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member3false0rr_ExpenseExampleNoRedemptionYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue185185falsefalsefalsetruefalse2truefalsetrue185185falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example falsefalse1 YearfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$2falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member4false0rr_ExpenseExampleNoRedemptionYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue602602falsefalsefalsetruefalse2truefalsetrue602602falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example falsefalse3 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$3falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member5false0rr_ExpenseExampleNoRedemptionYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue10441044falsefalsefalsetruefalse2truefalsetrue10441044falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions falsefalse5 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$4falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member6false0rr_ExpenseExampleNoRedemptionYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue20922092falsefalsefalsetruefalse2truefalsetrue22742274falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions falsefalse10 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$1falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Brr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010962Memberrr_ProspectusShareClassAxisexplicitMemberClass BUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue185185falsefalsefalsetruefalse2truefalsetrue602602falsefalsefalsetruefalse3truefalsetrue10441044falsefalsefalsetruefalse4truefalsetrue20922092falsefalsefalsetruefalseOthernanafalsefalseClass B2falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Crr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010963Memberrr_ProspectusShareClassAxisexplicitMemberClass CUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue185185falsefalsefalsetruefalse2truefalsetrue602602falsefalsefalsetruefalse3truefalsetrue10441044falsefalsefalsetruefalse4truefalsetrue22742274falsefalsefalsetruefalseOthernanafalsefalseClass C42Expense Example, No Redemption Delaware U.S. Growth Fund (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912MemberRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExampleNoRedemption.No authoritative reference available.falsefalseExpense Example, No Redemption [Table]15false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"><b> Portfolio turnover </b></p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 5 -Subsection instructions falsefalsePortfolio Turnover [Heading]16false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">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 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 22% of the average value of its portfolio.</p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subsection example falsefalsePortfolio Turnover [Text Block]17false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"><b> What are the Fund's principal investment strategies? </b></p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalseStrategy [Heading]18false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">We invest primarily in common stocks. The Fund invests primarily in companies that we believe have long-term capital appreciation potential and are expected to grow faster than the U.S. economy. Using a bottom up approach, we seek to select securities we believe have large end-market potential, dominant business models, and strong free cash flow generation that are attractively priced compared to the intrinsic value of the securities. We also consider a company's operational efficiencies, management's plans for capital allocation, and the company's shareholder orientation. All of these factors give us insight into the outlook for a company, helping identify companies poised for sustainable free cash flow growth. We believe that sustainable free cash flow growth, if it occurs, may result in price appreciation for the company's stock. We may sell a security if we no longer believe that the security is likely to contribute to meeting the investment objective of the Fund or if there are other opportunities that appear more attractive.</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">Under normal circumstances, the Fund will invest at least 80% of its net assets in U.S. investments. This policy is not a fundamental investment policy and may be changed without shareholder approval. However, shareholders will be given at least 60 days' notice prior to any such change. We may also invest up to 20% of the Fund's assets in debt securities and bonds. In addition, we may invest in convertible bonds, preferred stocks, and convertible preferred stocks, provided that these investments, when aggregated with the Fund's debt securities and bonds, do not exceed 35% of the Fund's assets.</p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalseStrategy Narrative [Text Block]19false0rr_RiskHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"><b> What are the principal risks of investing in the Fund? </b></p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b falsefalseRisk [Heading]20false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">Investing in any mutual fund involves the risk that you may lose part or all of the money you invest. Over time, the value of your investment in the Fund will increase and decrease according to changes in the value of the securities in the Fund's portfolio. Principal risks include:</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> <b>Investment not guaranteed by the Manager or its affiliates</b> -- Investments in the Fund are not and will not be deposits with or liabilities of Macquarie Bank Limited ABN 46 008 583 542 and its holding companies, including their subsidiaries or related companies (the "Macquarie Group"), and are subject to investment risk, including possible delays in repayment and loss of income and capital invested. No Macquarie Group company guarantees or will guarantee the performance of the Fund, the repayment of capital from the Fund, or any particular rate of return.</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> <b>Market risk</b> -- The risk that all or a majority of the securities in a certain market -- like the stock or bond market -- will decline in value because of factors such as adverse political or economic conditions, future expectations, investor confidence or heavy institutional selling.</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> <b>Foreign risk</b> -- The risk that foreign securities (particularly in emerging markets) may be adversely affected by political instability; changes in currency exchange rates; inefficient markets and higher transaction costs; foreign economic conditions; or inadequate or different regulatory and accounting standards.</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> <b>Currency risk</b> -- The risk that the value of a portfolio's investments may be negatively affected by changes in foreign currency exchange rates.</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> <b>Futures and options risk</b> -- The possibility that a fund may experience a loss if it employs an options or futures strategy related to a security or a market index and that security or index moves in the opposite direction from what the manager anticipated. Futures and options also involve additional expenses, which could reduce any benefit or increase any loss that a fund gains from using the strategy.</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> <b>Credit risk</b> -- The risk that a bond's issuer will be unable to make timely payments of interest and principal. Investing in so-called "junk" or "high yield" bonds entails greater risk of principal loss than the risk involved in investment grade bonds.</p> <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> <b>Liquidity risk</b> -- The possibility that securities cannot be readily sold within seven days at approximately the price at which a fund has valued them, which may prevent the Manager from disposing of securities at a favorable time or price during periods of infrequent trading of such securities.</p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringNarrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph i -Clause instruction -Subsection b falsefalseRisk Narrative [Text Block]21false0rr_BarChartAndPerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"><b> How has Delaware U.S. Growth Fund performed? </b></p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalseBar Chart and Performance Table [Heading]22false0rr_PerformanceNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance. The Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. The returns reflect expense caps in effect during these periods. The returns would be lower without the expense caps. You may obtain the Fund's most recently available month-end performance by calling 800 523-1918 or by visiting our web site at www.delawareinvestments.com/performance.</p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalsePerformance Narrative [Text Block]23false0rr_BarChartHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> Year-by-year total return (Class A) </p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalseBar Chart [Heading]24false0rr_BarChartTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://delaware/role/BarChartDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsefalseBarChart2.jpg<div style="display:none">~ http://delaware/role/BarChartDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>truehttp://delaware/role/BarChartDataAAAAfalsefalse020052 - Schedule - Annual Total Returns {Transposed}truefalsefalse1falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member3false0rr_AnnualReturn2001rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.2436-0.2436falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2001falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$2falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member4false0rr_AnnualReturn2002rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.2901-0.2901falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2002falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$3falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member5false0rr_AnnualReturn2003rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.23280.2328falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a -Subsection b falsefalseAnnual Return 2003falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$4falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member6false0rr_AnnualReturn2004rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.03010.0301falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a -Subsection b falsefalseAnnual Return 2004falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$5falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member7false0rr_AnnualReturn2005rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.13680.1368falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2005falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$6falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member8false0rr_AnnualReturn2006rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.02270.0227falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2006falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$7falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member9false0rr_AnnualReturn2007rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.12880.1288falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a -Subsection b falsefalseAnnual Return 2007falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$8falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member10false0rr_AnnualReturn2008rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.4367-0.4367falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2008falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$9falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member11false0rr_AnnualReturn2009rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.440.44falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a -Subsection b falsefalseAnnual Return 2009falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$10falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member12false0rr_AnnualReturn2010rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.13990.1399falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2010falsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$1falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010961Memberrr_ProspectusShareClassAxisexplicitMemberClass AUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.2436-0.2436falsefalsefalsetruefalse2truetruefalse-0.2901-0.2901falsefalsefalsetruefalse3truetruefalse0.23280.2328falsefalsefalsetruefalse4truetruefalse0.03010.0301falsefalsefalsetruefalse5truetruefalse0.13680.1368falsefalsefalsetruefalse6truetruefalse0.02270.0227falsefalsefalsetruefalse7truetruefalse0.12880.1288falsefalsefalsetruefalse8truetruefalse-0.4367-0.4367falsefalsefalsetruefalse9truetruefalse0.440.44falsefalsefalsetruefalse10truetruefalse0.13990.1399falsefalsefalsetruefalseOthernanafalsefalseClass A101Annual Total Returns Delaware U.S. Growth FundUnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912MemberRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No authoritative reference available.falsefalseBar Chart [Table]25false0rr_BarChartClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">During the periods illustrated in this bar chart, Class A's highest quarterly return was 15.50% for the quarter ended June 30, 2009 and its lowest quarterly return was -22.40% for the quarter ended December 31, 2008. The maximum Class A sales charge of 5.75%, which is normally deducted when you purchase shares, is not reflected in the highest/lowest quarterly returns or in the bar chart. If this fee were included, the returns would be less than those shown. The average annual returns in the table below do include the sales charge.</p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseBar Chart Closing [Text Block]26false0rr_PerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;"> Average annual total returns for periods ended December 31, 2010 </p> falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit c -Subsection b falsefalsePerformance Table Heading27false0rr_PerformanceTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://delaware/role/PerformanceTableDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>falsefalse<div style="display:none">~ http://delaware/role/PerformanceTableDataAAAA column period compact * column rr_ProspectusShareClassAxis compact * row primary compact * row dei_LegalEntityAxis compact delaware_S000003912Member ~</div>truehttp://delaware/role/PerformanceTableDataAAAAfalsefalse020062 - Schedule - Average Annual Total Returns {Transposed}truefalsefalse1falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member3false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.07470.0747falsefalsefalsetruefalse2truetruetrue0.07470.0747falsefalsefalsetruefalse3truetruetrue0.04910.0491falsefalsefalsetruefalse4truetruetrue0.09060.0906falsefalsefalsetruefalse5truetruetrue0.12070.1207falsefalsefalsetruefalse6truetruetrue0.13710.1371falsefalsefalsetruefalse7truetruetrue0.16710.1671falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalse1 YearfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$2falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member4false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00110.0011falsefalsefalsetruefalse2truetruetrue0.00110.0011falsefalsefalsetruefalse3truetruetrue0.0010.001falsefalsefalsetruefalse4truetruetrue0.00120.0012falsefalsefalsetruefalse5truetruetrue0.00560.0056falsefalsefalsetruefalse6truetruetrue0.01090.0109falsefalsefalsetruefalse7truetruetrue0.03750.0375falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalse5 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$3falseColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912Member5false0rr_AverageAnnualReturnYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue-0.0246-0.0246falsefalsefalsetruefalse2truetruetrue-0.0246-0.0246falsefalsefalsetruefalse3truetruetrue-0.0205-0.0205falsefalsefalsetruefalse4truetruetrue-0.0244-0.0244falsefalsefalsetruefalse5truetruetrue-0.0258-0.0258falsefalsefalsetruefalse6truetruetrue0.04220.0422falsefalsefalsetruefalse7truetruetrue0.00020.0002falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalse10 YearsfalsefalseDelaware U.S. Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_S000003912Memberdei_LegalEntityAxisexplicitMemberDelaware U.S. Growth FundfalseUSDfalsefalse$1falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010961Memberrr_ProspectusShareClassAxisexplicitMembertruefalsereturn before taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberClass Areturn before taxesUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.07470.0747falsefalsefalsetruefalse2truetruetrue0.00110.0011falsefalsefalsetruefalse3truetruetrue-0.0246-0.0246falsefalsefalsetruefalseOthernanafalsefalseClass A2falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010961Memberrr_ProspectusShareClassAxisexplicitMemberfalsefalsereturn after taxes on distributionsrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsMemberrr_PerformanceMeasureAxisexplicitMemberClass Areturn after taxes on distributionsStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.07470.0747falsefalsefalsetruefalse2truetruetrue0.00110.0011falsefalsefalsetruefalse3truetruetrue-0.0246-0.0246falsefalsefalsetruefalseOthernanafalsefalseClass A return after taxes on distributions3falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010961Memberrr_ProspectusShareClassAxisexplicitMemberfalsefalsereturn after taxes on distributions and sale of Fund sharesrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsAndSalesMemberrr_PerformanceMeasureAxisexplicitMemberClass Areturn after taxes on distributions and sale of Fund sharesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.04910.0491falsefalsefalsetruefalse2truetruetrue0.0010.001falsefalsefalsetruefalse3truetruetrue-0.0205-0.0205falsefalsefalsetruefalseOthernanafalsefalseClass A return after taxes on distributions and sale of Fund shares4falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Brr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010962Memberrr_ProspectusShareClassAxisexplicitMembertruefalsereturn before taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberClass Breturn before taxesUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.09060.0906falsefalsefalsetruefalse2truetruetrue0.00120.0012falsefalsefalsetruefalse3truetruetrue-0.0244-0.0244falsefalsefalsetruefalseOthernanafalsefalseClass B5falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Crr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010963Memberrr_ProspectusShareClassAxisexplicitMembertruefalsereturn before taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberClass Creturn before taxesUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.12070.1207falsefalsefalsetruefalse2truetruetrue0.00560.0056falsefalsefalsetruefalse3truetruetrue-0.0258-0.0258falsefalsefalsetruefalseOthernanafalsefalseClass C6falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00falsefalseClass Rrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_C000010964Memberrr_ProspectusShareClassAxisexplicitMembertruefalsereturn before taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberClass Rreturn before taxesUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.13710.1371falsefalsefalsetruefalse2truetruetrue0.01090.0109falsefalsefalsetruefalse3truetruetrue0.04220.0422falsefalsefalsetruefalseOthernanafalsefalseClass R7falseRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-04-15T00:00:002011-04-15T00:00:00truefalseShare Classesrr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseRussell 1000(R) Growth Index (reflects no deduction for fees, expenses, or taxes)rr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldidelaware_benchmark0119AAAAMemberrr_PerformanceMeasureAxisexplicitMemberShare ClassesRussell 1000(R) Growth Index (reflects no deduction for fees, expenses, or taxes)Standard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.16710.1671falsefalsefalsetruefalse2truetruetrue0.03750.0375falsefalsefalsetruefalse3truetruetrue0.00020.0002falsefalsefalsetruefalseOthernanafalsefalseRussell 1000(R) Growth Index (reflects no deduction for fees, expenses, or taxes)37Average Annual Total Returns Delaware U.S. Growth FundUnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*Columndei_LegalEntityAxisAxisdelaware_S000003912MemberRowperiodPeriod*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No authoritative reference available.falsefalsePerformance [Table]28false0rr_PerformanceTableClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <p style="font-size:12;padding-top:2;padding-bottom:0;padding-left:0;">After-tax performance is only presented for Class A shares of the Fund. The after-tax returns for other Fund classes may vary. Actual after-tax returns depend on the investor's individual tax situation and may differ from the returns shown. After-tax returns are not relevant for shares held in tax-deferred investment vehicles such as employer-sponsored 401(k) plans and individual retirement accounts (IRAs). The after-tax returns shown are calculated using the highest individual federal marginal income tax rates in effect during the periods presented and do not reflect the impact of state and local taxes.</p> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a table showing the Fund's (A) average annual total return; (B) average annual total return (after taxes on distributions); and (C) average annual total return (after taxes on distributions and redemption). A Money Market Fund should show only the returns described in clause (A) of the preceding sentence. All returns should be shown for 1-, 5-, and 10- calendar year periods ending on the date of the most recently completed calendar year (or for the life of the Fund, if shorter), but only for periods subsequent to the effective date of the Fund's registration statement. The table also shouldshow the returns of an appropriate broadbased securities market index as defined in Instruction 5 to Item 22(b)(7) for the same periods. A Fund that has been in existence for more than 10 years also may include returns for the life of the Fund. A Money Market Fund may provide the Fund's 7-day yield ending on the date of the most recent calendar year or disclose a toll-free (or collect) telephone number that investors can use to obtain the Fund's current 7-day yield. For a Fund (other than a Money Market Fund or a Fund described in General Instruction C.3.(d)(iii)), provide the information in the following table with the specified captions AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, _____)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Subsection b falsefalsePerformance Table Closing [Text Block]127Delaware U.S. Growth Fund (Delaware U.S. Growth Fund, Delaware U.S. Growth Fund)UnKnownUnKnownUnKnownUnKnownfalsetrue