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Label Element Value
Prospectus [Line Items] rr_ProspectusLineItems  
SEC Form dei_DocumentType 485BPOS
Period end date dei_DocumentPeriodEndDate Oct. 31, 2020
Registrant Name dei_EntityRegistrantName DELAWARE GROUP ADVISER FUNDS
Registrant CIK dei_EntityCentralIndexKey 0000910682
Amendment Flag dei_AmendmentFlag false
Prospectus #1  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return rr_RiskReturnHeading Prospectus
Prospectus #1 | Class A  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DPDFX
Prospectus #1 | Class C  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DPCFX
Prospectus #1 | Class R  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DPRFX
Prospectus #1 | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DPFFX
Prospectus #1 | Class R6  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DPZRX
Prospectus #1 | Delaware Diversified Income Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Objective rr_ObjectiveHeading What is the Fund’s investment objective?
Objective, Primary rr_ObjectivePrimaryTextBlock

Delaware Diversified Income Fund seeks maximum long-term total return, consistent with reasonable risk.
Expense rr_ExpenseHeading What are the Fund’s fees and expenses?
Expense Narrative rr_ExpenseNarrativeTextBlock

The table below 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 $100,000 in Delaware Funds® by Macquarie. More information about these and other discounts is available from your financial intermediary, in the Fund’s Prospectus under the section entitled “About your account,” and in the Fund’s statement of additional information (SAI) under the section entitled “Purchasing Shares.”

Operating Expenses Caption rr_OperatingExpensesCaption Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in the annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 112% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 112.00%
Expense Breakpoint Discounts rr_ExpenseBreakpointDiscounts You may qualify for sales-charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in Delaware Funds® by Macquarie.
Expense Breakpoint, Minimum Investment Required rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 100,000
Expense Example rr_ExpenseExampleHeading Example
Expense Example Narrative rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. In addition, the example shows expenses for Class C shares, assuming those shares were not redeemed at the end of those periods. The example also assumes that your investment has a 5% return each year and reflects the Manager’s expense 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:
Strategy rr_StrategyHeading What are the Fund’s principal investment strategies?
Strategy Narrative rr_StrategyNarrativeTextBlock

The Fund allocates its investments principally among the following four sectors of the fixed income securities markets: the US investment grade sector, the US high yield sector, the international developed markets sector, and the emerging markets sector. Under normal circumstances, the Fund will invest at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in fixed income securities (80% policy). The Fund’s investment manager, Delaware Management Company (Manager), will determine how much of the Fund’s assets to allocate to each of the four sectors, based on its evaluation of economic and market conditions, and its assessment of the returns and potential for appreciation that can be achieved from investments in each of the four sectors. The Manager will periodically reallocate the Fund’s assets as deemed necessary. In addition, the Manager may seek investment advice and recommendations from its affiliates: Macquarie Investment Management Europe Limited, Macquarie Investment Management Austria Kapitalanlage AG, and Macquarie Investment Management Global Limited (together, the “Affiliated Sub-Advisors”). The Manager may also permit these Affiliated Sub-Advisors to execute Fund security trades on behalf of the Manager and exercise investment discretion for securities in certain markets where DMC believes it will be beneficial to utilize an Affiliated Sub-Advisor’s specialized market knowledge.

Under normal circumstances, between 5% and 35% of the Fund’s net assets will be allocated to the US high yield sector. The Fund’s investments in emerging markets will, in the aggregate, be limited to no more than 20% of the Fund’s net assets. The Fund will limit its investments in foreign securities to between 5% and 40% of its net assets and will seek to hedge its foreign currency exposure, which will be limited to 20% of the Fund’s net assets, by entering into forward foreign currency contracts.

The Fund may hold a substantial portion of its assets in cash or short-term fixed income obligations in unusual market conditions to meet redemption requests, for temporary defensive purposes, and pending investment. The Fund may invest in mortgage-backed securities and other asset-backed securities. The Fund may also use a wide range of derivatives instruments, typically including options, futures contracts, options on futures contracts, and swaps. The Fund will use derivatives for both hedging and nonhedging purposes. For example, the Fund may invest in: futures and options to manage duration and for defensive purposes, such as to protect gains or hedge against potential losses in the portfolio without actually selling a security, or to stay fully invested; forward foreign currency contracts to manage foreign currency exposure; interest rate swaps to neutralize the impact of interest rate changes; credit default swaps to hedge against a credit event, to gain exposure to certain securities or markets, or to enhance total return; and index swaps to enhance return or to effect diversification. The Fund will not use derivatives for reasons inconsistent with its investment objective.

The Fund’s 80% policy is nonfundamental and may be changed without shareholder approval. Fund shareholders would be given at least 60 days’ notice prior to any such change.
Strategy Portfolio Concentration rr_StrategyPortfolioConcentration The Fund allocates its investments principally among the following four sectors of the fixed income securities markets: the US investment grade sector, the US high yield sector, the international developed markets sector, and the emerging markets sector.
Risk rr_RiskHeading What are the principal risks of investing in the Fund?
Risk Narrative rr_RiskNarrativeTextBlock

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. An investment in the Fund may not be appropriate for all investors. The Fund’s principal risks include:

Market risk — The risk that all or a majority of the securities in a certain market — such as 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.

Credit risk — The risk that an issuer of a debt security, including a governmental issuer or an entity that insures a bond, may be unable to make interest payments and/or repay principal in a timely manner.

High yield (junk bond) risk — The risk that high yield securities, commonly known as “junk bonds,” are subject to reduced creditworthiness of issuers, increased risk of default, and a more limited and less liquid secondary market. High yield securities may also be subject to greater price volatility and risk of loss of income and principal than are higher-rated securities. High yield bonds are sometimes issued by municipalities that have less financial strength and therefore have less ability to make projected debt payments on the bonds.

Interest rate risk — The risk that the prices of bonds and other fixed income securities will increase as interest rates fall and decrease as interest rates rise. Interest rate changes are influenced by a number of factors, such as government policy, monetary policy, inflation expectations, and the supply and demand of

 

bonds. Bonds and other fixed income securities with longer maturities or duration generally are more sensitive to interest rate changes. A fund may be subject to a greater risk of rising interest rates due to the current period of historically low interest rates.

Loans and other indebtedness risk — The risk that a fund will not receive payment of principal, interest, and other amounts due in connection with these investments and will depend primarily on the financial condition of the borrower and the lending institution. A fund’s ability to sell its loans or to realize their full value upon sale may also be impaired due to the lack of an active trading market, irregular trading activity, wide bid/ask spreads, contractual restrictions, and extended trade settlement periods. In addition, certain loans in which a fund invests may not be considered securities. A fund therefore may not be able to rely upon the anti-fraud provisions of the federal securities laws with respect to these investments.

Prepayment risk — The risk that the principal on mortgage-backed or asset-backed securities may be prepaid at any time, which will reduce the yield and market value. A fund may then have to reinvest that money at a lower interest rate.

Foreign risk — 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, the imposition of economic or trade sanctions, or inadequate or different regulatory and accounting standards.

Derivatives risk — Derivatives contracts, such as futures, forward foreign currency contracts, options, and swaps, may involve additional expenses (such as the payment of premiums) and are subject to significant loss if a security, index, reference rate, or other asset or market factor to which a derivatives contract is associated, moves in the opposite direction from what the portfolio manager anticipated. When used for hedging, the change in value of the derivatives instrument may also not correlate specifically with the currency, rate, or other risk being hedged, in which case a fund may not realize the intended benefits. Derivatives contracts are also subject to the risk that the counterparty may fail to perform its obligations under the contract due to, among other reasons, financial difficulties (such as a bankruptcy or reorganization).

Leveraging risk — The risk that certain fund transactions, such as reverse repurchase agreements, short sales, loans of portfolio securities, and the use of when-issued, delayed delivery or forward commitment transactions, or derivatives instruments, may give rise to leverage, causing a fund to be more volatile than if it had not been leveraged, which may result in increased losses to the fund.

Liquidity risk — The possibility that investments cannot be readily sold within seven calendar days at approximately the price at which a fund has valued them.

Valuation risk — The risk that a less liquid secondary market may make it more difficult for a fund to obtain precise valuations of certain securities in its portfolio.

Government and regulatory risk — The risk that governments or regulatory authorities may take actions that could adversely affect various sectors of the securities markets and affect fund performance.

IBOR risk — The risk that changes related to the use of the London Interbank Offered Rate (LIBOR) or similar interbank offered rates (“IBORs,” such as the Euro Overnight Index Average (EONIA)) could have adverse impacts on financial instruments that reference LIBOR or a similar rate. While some instruments may contemplate a scenario where LIBOR or a similar rate is no longer available by providing for an alternative rate setting methodology, not all instruments have such fallback provisions and the effectiveness of replacement rates is uncertain. The abandonment of LIBOR and similar rates could affect the value and liquidity of instruments that reference such rates, especially those that do not have fallback provisions. The use of alternative reference rate products may impact investment strategy performance.

Active management and selection risk — The risk that the securities selected by a fund’s management will underperform the markets, the relevant indices, or the securities selected by other funds with similar investment objectives and investment strategies. The securities and sectors selected may vary from the securities and sectors included in the relevant index.
Risk Closing rr_RiskClosingTextBlock

The Manager is an indirect wholly owned subsidiary of Macquarie Group Limited (MGL). Other than Macquarie Bank Limited (MBL), a subsidiary of MGL and an affiliate of the Manager, none of the entities noted are authorized deposit-taking institutions for the purposes of the Banking Act 1959 (Commonwealth of Australia). The obligations of these entities do not represent deposits or other liabilities of MBL. MBL does not guarantee or otherwise provide assurance in respect of the obligations of these entities, unless noted otherwise. The Fund is governed by US laws and regulations.

Risk Lose Money rr_RiskLoseMoney 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.
Bar Chart and Performance Table rr_BarChartAndPerformanceTableHeading How has Delaware Diversified Income Fund performed?
Performance Narrative rr_PerformanceNarrativeTextBlock

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual total returns for the 1-, 5-, and 10-year or lifetime periods 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 any

 

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 website at delawarefunds.com/performance.
Performance Availability Phone rr_PerformanceAvailabilityPhone 800 523-1918
Performance Availability Website Address rr_PerformanceAvailabilityWebSiteAddress delawarefunds.com/performance
Performance Past Does Not Indicate Future rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods illustrated in this bar chart, Class A’s highest quarterly return was 6.77% for the quarter ended June 30, 2020, and its lowest quarterly return was -3.63% for the quarter ended June 30, 2013. The maximum Class A sales charge of 4.50%, 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 total returns in the table below do include the sales charge.

Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate 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.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred After-tax returns are not relevant for shares held in tax-advantaged investment vehicles such as employer-sponsored 401(k) plans and individual retirement accounts (IRAs).
Performance Table One Class of after Tax Shown rr_PerformanceTableOneClassOfAfterTaxShown After-tax performance is presented only for Class A shares of the Fund.
Performance Table Closing rr_PerformanceTableClosingTextBlock

After-tax performance is presented only 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-advantaged 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.
Prospectus #1 | Delaware Diversified Income Fund | Bloomberg Barclays US Aggregate Index  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
1 year rr_AverageAnnualReturnYear01 7.51%
5 years rr_AverageAnnualReturnYear05 4.44%
10 years or lifetime rr_AverageAnnualReturnYear10 3.84%
Prospectus #1 | Delaware Diversified Income Fund | Class A  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.50%
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management fees rr_ManagementFeesOverAssets 0.46%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.16% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 0.87%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.17%) [3]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 0.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 518
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 699
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 895
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,459
2011 rr_AnnualReturn2011 6.38%
2012 rr_AnnualReturn2012 6.88%
2013 rr_AnnualReturn2013 (1.37%)
2014 rr_AnnualReturn2014 5.11%
2015 rr_AnnualReturn2015 (1.15%)
2016 rr_AnnualReturn2016 3.56%
2017 rr_AnnualReturn2017 5.26%
2018 rr_AnnualReturn2018 (2.23%)
2019 rr_AnnualReturn2019 10.76%
2020 rr_AnnualReturn2020 10.55%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 6.77%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.63%)
1 year rr_AverageAnnualReturnYear01 5.52%
5 years rr_AverageAnnualReturnYear05 4.51%
10 years or lifetime rr_AverageAnnualReturnYear10 3.80%
Prospectus #1 | Delaware Diversified Income Fund | Class A | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
1 year rr_AverageAnnualReturnYear01 4.28%
5 years rr_AverageAnnualReturnYear05 3.16%
10 years or lifetime rr_AverageAnnualReturnYear10 2.33%
Prospectus #1 | Delaware Diversified Income Fund | Class A | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
1 year rr_AverageAnnualReturnYear01 3.23%
5 years rr_AverageAnnualReturnYear05 2.84%
10 years or lifetime rr_AverageAnnualReturnYear10 2.28%
Prospectus #1 | Delaware Diversified Income Fund | Class C  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00% [1]
Management fees rr_ManagementFeesOverAssets 0.46%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other expenses rr_OtherExpensesOverAssets 0.16% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 1.62%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.17%) [3]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 1.45%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 248
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 495
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 865
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,908
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 148
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 495
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 865
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,908
1 year rr_AverageAnnualReturnYear01 8.72%
5 years rr_AverageAnnualReturnYear05 4.68%
10 years or lifetime rr_AverageAnnualReturnYear10 3.50%
Prospectus #1 | Delaware Diversified Income Fund | Class R  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management fees rr_ManagementFeesOverAssets 0.46%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other expenses rr_OtherExpensesOverAssets 0.16% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.17%) [3]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 339
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 600
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,348
1 year rr_AverageAnnualReturnYear01 10.40%
5 years rr_AverageAnnualReturnYear05 5.23%
10 years or lifetime rr_AverageAnnualReturnYear10 4.02%
Prospectus #1 | Delaware Diversified Income Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management fees rr_ManagementFeesOverAssets 0.46%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.16% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 0.62%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.17%) [3]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 0.45%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 46
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 181
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 329
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 758
1 year rr_AverageAnnualReturnYear01 10.94%
5 years rr_AverageAnnualReturnYear05 5.75%
10 years or lifetime rr_AverageAnnualReturnYear10 4.54%
Prospectus #1 | Delaware Diversified Income Fund | Class R6  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [1]
Management fees rr_ManagementFeesOverAssets 0.46%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.07% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 0.53%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.17%) [3]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 0.36%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 37
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 153
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 279
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 649
1 year rr_AverageAnnualReturnYear01 11.04%
Lifetime rr_AverageAnnualReturnSinceInception 5.51%
Inception Date rr_AverageAnnualReturnInceptionDate May 02, 2016
Prospectus #2  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return rr_RiskReturnHeading Prospectus
Prospectus #2 | Class A  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DUGAX
Prospectus #2 | Class C  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DEUCX
Prospectus #2 | Class R  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DEURX
Prospectus #2 | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DEUIX
Prospectus #2 | Class R6  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol DUZRX
Prospectus #2 | Delaware U.S. Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Objective rr_ObjectiveHeading What is the Fund’s investment objective?
Objective, Primary rr_ObjectivePrimaryTextBlock

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.
Expense rr_ExpenseHeading What are the Fund’s fees and expenses?
Expense Narrative rr_ExpenseNarrativeTextBlock

The table below 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 Funds® by Macquarie. More information about these and other discounts is available from your financial intermediary, in the Fund’s Prospectus under the section entitled “About your account,” and in the Fund’s statement of additional information (SAI) under the section entitled “Purchasing Shares.”

Operating Expenses Caption rr_OperatingExpensesCaption Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in the annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 54% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 54.00%
Expense Breakpoint Discounts rr_ExpenseBreakpointDiscounts 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 Funds® by Macquarie.
Expense Breakpoint, Minimum Investment Required rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expense Example rr_ExpenseExampleHeading Example
Expense Example Narrative rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. In addition, the example shows expenses for Class C shares, assuming those shares were not redeemed at the end of those periods. The example also assumes that your investment has a 5% return each year and reflects the Manager’s expense 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:
Strategy rr_StrategyHeading What are the Fund’s principal investment strategies?
Strategy Narrative rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund will invest at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in US investments (80% policy). The Fund invests primarily in common stocks of companies that its portfolio managers believe have long-term capital appreciation potential and are expected to grow faster than the US economy. Using a bottom-up approach, the portfolio managers seek to select securities they 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. The portfolio managers also consider a company’s operational efficiencies, management’s plans for capital allocation, and the company’s shareholder orientation. All of these factors give the portfolio managers insight into the outlook for a company, helping identify companies poised for sustainable free cash flow growth. The portfolio managers believe that sustainable free cash flow growth, if it occurs, may result in price appreciation for the company’s stock. The portfolio managers may sell a security if they 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.

The Fund’s 80% policy is nonfundamental and may be changed without shareholder approval. Fund shareholders would be given at least 60 days’ notice prior to any such change.
Strategy Portfolio Concentration rr_StrategyPortfolioConcentration Under normal circumstances, the Fund will invest at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in US investments (80% policy).
Risk rr_RiskHeading What are the principal risks of investing in the Fund?
Risk Narrative rr_RiskNarrativeTextBlock

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. An investment in the Fund may not be appropriate for all investors. The Fund’s principal risks include:

Market risk — The risk that all or a majority of the securities in a certain market — such as 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.

Liquidity risk — The possibility that investments cannot be readily sold within seven calendar days at approximately the price at which a fund has valued them.

Foreign risk — 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, the imposition of economic or trade sanctions, or inadequate or different regulatory and accounting standards.

IBOR risk — The risk that changes related to the use of the London Interbank Offered Rate (LIBOR) or similar interbank offered rates (“IBORs,” such as the Euro Overnight Index Average (EONIA)) could have adverse impacts on financial instruments that reference LIBOR or a similar rate. While some instruments may contemplate a scenario where LIBOR or a similar rate is no longer available by providing for an alternative rate setting methodology, not all instruments have such fallback provisions and the effectiveness of replacement rates is uncertain. The abandonment of LIBOR and similar rates could affect the value and liquidity of instruments that reference such rates, especially those that do not have fallback provisions. The use of alternative reference rate products may impact investment strategy performance.

Active management and selection risk — The risk that the securities selected by a fund’s management will underperform the markets, the relevant indices, or the securities selected by other funds with similar investment objectives and investment strategies. The securities and sectors selected may vary from the securities and sectors included in the relevant index.
Risk Closing rr_RiskClosingTextBlock

The Manager is an indirect wholly owned subsidiary of Macquarie Group Limited (MGL). Other than Macquarie Bank Limited (MBL), a subsidiary of MGL and an affiliate of the Manager, none of the entities noted are authorized deposit-taking institutions for the purposes of the Banking Act 1959 (Commonwealth of Australia). The obligations of these entities do not represent deposits or other liabilities of MBL. MBL does not guarantee or otherwise provide assurance in respect of the obligations of these entities, unless noted otherwise. The Fund is governed by US laws and regulations.

Risk Lose Money rr_RiskLoseMoney 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.
Bar Chart and Performance Table rr_BarChartAndPerformanceTableHeading How has Delaware U.S. Growth Fund performed?
Performance Narrative rr_PerformanceNarrativeTextBlock

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual total returns for the 1-, 5-, and 10-year or lifetime periods 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 any 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 website at delawarefunds.com/performance.
Performance Availability Phone rr_PerformanceAvailabilityPhone 800 523-1918
Performance Availability Website Address rr_PerformanceAvailabilityWebSiteAddress delawarefunds.com/performance
Performance Past Does Not Indicate Future rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods illustrated in this bar chart, Class A’s highest quarterly return was 29.79% for the quarter ended June 30, 2020, and its lowest quarterly return was -14.19% for the quarter ended Dec. 31, 2018. 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 total returns in the table below do include the sales charge.

Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate 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.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred After-tax returns are not relevant for shares held in tax-advantaged investment vehicles such as employer-sponsored 401(k) plans and individual retirement accounts (IRAs).
Performance Table One Class of after Tax Shown rr_PerformanceTableOneClassOfAfterTaxShown After-tax performance is presented only for Class A shares of the Fund.
Performance Table Closing rr_PerformanceTableClosingTextBlock

After-tax performance is presented only 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-advantaged 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.
Prospectus #2 | Delaware U.S. Growth Fund | Russell 1000® Growth Index  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
1 year rr_AverageAnnualReturnYear01 38.49%
5 years rr_AverageAnnualReturnYear05 21.00%
10 years or lifetime rr_AverageAnnualReturnYear10 17.21%
Prospectus #2 | Delaware U.S. Growth Fund | Class A  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [4]
Management fees rr_ManagementFeesOverAssets 0.58%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.29% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.03%) [6]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 680
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 908
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,154
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,857
2011 rr_AnnualReturn2011 7.73%
2012 rr_AnnualReturn2012 15.67%
2013 rr_AnnualReturn2013 33.86%
2014 rr_AnnualReturn2014 12.44%
2015 rr_AnnualReturn2015 4.88%
2016 rr_AnnualReturn2016 (5.39%)
2017 rr_AnnualReturn2017 27.89%
2018 rr_AnnualReturn2018 (3.50%)
2019 rr_AnnualReturn2019 26.85%
2020 rr_AnnualReturn2020 44.17%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 29.79%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.19%)
1 year rr_AverageAnnualReturnYear01 35.86%
5 years rr_AverageAnnualReturnYear05 15.01%
10 years or lifetime rr_AverageAnnualReturnYear10 14.75%
Prospectus #2 | Delaware U.S. Growth Fund | Class A | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
1 year rr_AverageAnnualReturnYear01 32.35%
5 years rr_AverageAnnualReturnYear05 11.65%
10 years or lifetime rr_AverageAnnualReturnYear10 12.68%
Prospectus #2 | Delaware U.S. Growth Fund | Class A | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
1 year rr_AverageAnnualReturnYear01 23.61%
5 years rr_AverageAnnualReturnYear05 11.08%
10 years or lifetime rr_AverageAnnualReturnYear10 11.79%
Prospectus #2 | Delaware U.S. Growth Fund | Class C  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00% [4]
Management fees rr_ManagementFeesOverAssets 0.58%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other expenses rr_OtherExpensesOverAssets 0.29% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 1.87%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.03%) [6]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 1.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 287
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 585
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,008
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,188
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 187
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 585
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,008
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,188
1 year rr_AverageAnnualReturnYear01 42.07%
5 years rr_AverageAnnualReturnYear05 15.50%
10 years or lifetime rr_AverageAnnualReturnYear10 14.57%
Prospectus #2 | Delaware U.S. Growth Fund | Class R  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [4]
Management fees rr_ManagementFeesOverAssets 0.58%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other expenses rr_OtherExpensesOverAssets 0.29% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 1.37%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.03%) [6]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 1.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 136
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 431
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 747
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,644
1 year rr_AverageAnnualReturnYear01 43.81%
5 years rr_AverageAnnualReturnYear05 16.09%
10 years or lifetime rr_AverageAnnualReturnYear10 15.14%
Prospectus #2 | Delaware U.S. Growth Fund | Institutional Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [4]
Management fees rr_ManagementFeesOverAssets 0.58%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.29% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 0.87%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.03%) [6]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 0.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 275
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 479
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,070
1 year rr_AverageAnnualReturnYear01 44.49%
5 years rr_AverageAnnualReturnYear05 16.67%
10 years or lifetime rr_AverageAnnualReturnYear10 15.72%
Prospectus #2 | Delaware U.S. Growth Fund | Class R6  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum sales charge (load) imposed on purchases as a percentage of offering price rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum contingent deferred sales charge (load) as a percentage of original purchase price or redemption price, whichever is lower rr_MaximumDeferredSalesChargeOverOfferingPrice none [4]
Management fees rr_ManagementFeesOverAssets 0.58%
Distribution and service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.07% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 0.65%
Fee waivers and expense reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.03%) [6]
Total annual fund operating expenses after fee waivers and expense reimbursements rr_NetExpensesOverAssets 0.62%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 63
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 205
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 359
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 808
1 year rr_AverageAnnualReturnYear01 44.82%
Lifetime rr_AverageAnnualReturnSinceInception 20.12%
Inception Date rr_AverageAnnualReturnInceptionDate May 02, 2016
[1] Class C shares redeemed within one year of purchase are subject to a 1.00% contingent deferred sales charge (CDSC).
[2] “Other expenses” account for Class R6 shares not being subject to certain expenses as described further in the section of the Prospectus entitled “Choosing a share class.”
[3] 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 fees, acquired fund fees and expenses, taxes, interest, short sale dividend and 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 0.45% of the Fund's average daily net assets for all share classes other than Class R6, and 0.36% of the Fund's Class R6 shares' average daily net assets, from Feb. 26, 2021 through March 1, 2022. These waivers and reimbursements may only be terminated by agreement of the Manager and the Fund.
[4] Class C shares redeemed within one year of purchase are subject to a 1.00% contingent deferred sales charge (CDSC).
[5] “Other expenses” account for Class R6 shares not being subject to certain expenses as described further in the section of the Prospectus entitled “Choosing a share class.”
[6] 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 fees, acquired fund fees and expenses, taxes, interest, short sale dividend and 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 0.84% of the Fund’s average daily net assets for all share classes other than Class R6, and 0.62% of the Fund's Class R6 shares' average daily net assets, from Feb. 26, 2021 through March 1, 2022. These waivers and reimbursements may only be terminated by agreement of the Manager and the Fund.