2.2.0.25truefalse040000 - Disclosure - Risk/Return Detail Data {Elements}truetruefalse1falsefalsefalsefalse1/28/2010 - 1/28/2011 eol_0001111178-11-000004_STD_366_20110128_0http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00pureStandardhttp://www.xbrl.org/2003/instancepure0iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso421702true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:3false0dei_DocumentTypedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00485BPOSfalsefalsefalsefalsefalseOtherus-types:SECReportItemTypenaThe type of document being provided (such as 10-K, 10-Q, N-1A, etc). The document type should be limited to the same value as the supporting SEC submission type. The acceptable values are as follows: S-1, S-3, S-4, S-11, F-1, F-3, F-4, F-9, F-10, 6-K, 8-K, 10, 10-K, 10-Q, 20-F, 40-F, N-1A, 485BPOS, NCSR, N-Q, and Other.No authoritative reference available.falsefalseDocument Type4false0dei_DocumentPeriodEndDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002010-09-30falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements this will be the filing date. The format of the date is CCYY-MM-DD.No authoritative reference available.falsefalseDocument Period End Date5false0dei_EntityRegistrantNamedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00DREYFUS OPPORTUNITY FUNDSfalsefalsefalsefalsefalseOtherxbrli:normalizedStringItemTypenormalizedstringThe exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 falsefalseRegistrant Name6false0dei_EntityCentralIndexKeydeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse000001111178falsefalsefalsefalsefalseOtherus-types:centralIndexKeyItemTypenaA unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 falsefalseCentral Index Key7false0dei_AmendmentFlagdeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalsefalseOtherxbrli:booleanItemTypenaIf the value is true, then the document as an amendment to previously-filed/accepted document.No authoritative reference available.falsefalseAmendment Flag8false0dei_DocumentCreationDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-01-28falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.No authoritative reference available.falsefalseDocument Creation Date9false0dei_DocumentEffectiveDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-02-01falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.No authoritative reference available.falsefalseDocument Effective Date10false0rr_ProspectusDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-02-01falsefalsetruefalsefalseOtherxbrli:dateItemTypedateThe date of the prospectus.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 1 -Paragraph 3 -Subsection a falsefalseProspectusDate11false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse2falsefalseUSDtruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund 1/28/2010 - 1/28/2011 USD ($) $eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170pureStandardhttp://www.xbrl.org/2003/instancepure0USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund12true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:13false0rr_RiskReturnHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Fund SummaryfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicatedReference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 falsefalseRisk/Return, Heading14false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Investment ObjectivefalsefalsefalsefalsefalseOtherxbrli: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 falsefalseInvestment Objective, Heading15false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The fund seeks long-term capital appreciation.</pre>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 falsefalseinvestment Objective, Primary16false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Fees and ExpensesfalsefalsefalsefalsefalseOtherxbrli: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, Heading17false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in certain funds in the Dreyfus Family of Funds. More information about these and other discounts is available from your financial professional and in the Shareholder Guide section on page 9 of the Prospectus and in the How to Buy Shares section on page B-37 of the fund's Statement of Additional Information.</pre>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, Narrative18false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Shareholder Fees (fees paid directly from your investment)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, Caption19false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)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, Caption20false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Portfolio TurnoverfalsefalsefalsefalsefalseOtherxbrli: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, Heading21false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>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 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 58.38% of the average value of its portfolio.</pre>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 Turnover22false0rr_PortfolioTurnoverRaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.58380.5838falsefalsefalsefalsefalseOtherxbrli:pureItemTypepureThis element represents the rate of portfolio turnover presented as a percentage (SEC Form N-1A 2006-09-14 A.3.example.3 Portfolio Turnover A.3.instructions.5 Portfolio Turnover).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subsection example falsefalsePortfolio Turnover, Rate23false0rr_ExpenseBreakpointDiscountsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in certain funds in the Dreyfus Family of Funds.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInclude 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.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Breakpoint, Discounts24false0rr_ExpenseBreakpointMinimumInvestmentRequiredAmountrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse5000050000falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis element represents the minimum level of investment required to qualify for discounted sales charges or fund expenses (SEC Form N-1A 2006-09-14 A.3.instructions.1.b).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Breakpoint, Minimum Investment Required Amount25false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00ExamplefalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalseExpense Example, Heading26false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. The ten-year example for Class B assumes conversion of Class B to Class A at the end of the sixth year following the date of purchase. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</pre>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, Narrative27false0rr_ExpenseExampleNoRedemptionByYearCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00You would pay the following expenses if you did not redeem your shares:falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringYou 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 falsefalseExpense Example, No Redemption, By Year, Caption28false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Principal Investment StrategyfalsefalsefalsefalsefalseOtherxbrli: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 falsefalseInvestment Strategy, Heading29false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>To pursue its goal, the fund normally invests at least 80% of its assets in stocks of companies in the natural resources and natural resources related sectors. Generally, these are companies principally engaged in owning or developing natural resources, or supplying goods, technology and services relating to natural resources. The fund invests in growth and value stocks and typically will maintain exposure to the major natural resources sectors. There are no prescribed limits on the weightings of securities in any particular natural resources sector or in any individual company, and the fund may invest in companies of any market capitalization. The fund typically will invest in equity securities of U.S.-based companies, but may invest up to 45% of its total assets in foreign securities, including emerging market securities.</pre>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 falsefalseInvestment Strategy, Narrative30false0rr_StrategyPortfolioConcentrationrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00To pursue its goal, the fund normally invests at least 80% of its assets in stocks of companies in the natural resources and natural resources related sectors.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 falsefalseInvestment Strategy, Portfolio Concentration31false0rr_RiskHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Principal RisksfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b falsefalseRisk, Heading32false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>An investment in the fund is not a bank deposit. It is not insured or guaranteed by the FDIC or any other government agency. It is not a complete investment program. The fund's share price fluctuates, sometimes dramatically, which means you could lose money. o Natural resources sector risk. Investments in the natural resources and related sectors may be affected by numerous factors, including events occurring in nature, inflationary pressures and domestic and international politics. For example, events occurring in nature (such as earthquakes or fires in prime natural resource areas) and political events (such as coups or military confrontations) can affect the overall supply of a natural resource and the value of companies involved in such natural resource. Political risks and other risks to which foreign securities are subject also may affect domestic companies in which the fund invests if they have significant operations or investments in foreign countries. In addition, interest rates, prices of raw materials and other commodities, international economic developments, energy conservation, tax and other government regulations (both domestic and foreign) may affect the supply of and demand for natural resources, which can affect the profitability and value of securities issued by companies in the natural resources sectors. Securities of companies within specific natural resources sectors can perform differently than the overall market. This may be due to changes in such things as the regulatory or competitive environment or to changes in investor perceptions regarding a sector. Because the fund may allocate relatively more assets to certain natural resources sectors than others, the fund's performance may be more sensitive to developments which affect those sectors emphasized by the fund. o Risks of stock investing. Stocks generally fluctuate more in value than bonds and may decline significantly over short time periods. There is the chance that stock prices overall will decline because stock markets tend to move in cycles, with periods of rising prices and falling prices. The market value of a stock may decline due to general market conditions that are not related to the particular company, such as real or perceived adverse economic conditions, changes in the outlook for corporate earnings, changes in interest or currency rates, or adverse investor sentiment generally. A security's market value also may decline because of factors that affect a particular industry, such as labor shortages or increased production costs and competitive conditions within an industry, or factors that affect a particular company, such as management performance, financial leverage, and reduced demand for the company's products or services. o Issuer risk. The value of a security may decline for a number of reasons which directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer's products or services. o Growth and value stock risk. By investing in a mix of growth and value companies, the fund assumes the risks of both. Investors often expect growth companies to increase their earnings at a certain rate. If these expectations are not met, investors can punish the stocks inordinately, even if earnings do increase. In addition, growth stocks typically lack the dividend yield that can cushion stock prices in market downturns. Value stocks involve the risk that they may never reach their expected full market value, either because the market fails to recognize the stock's intrinsic worth, or the expected value was misgauged. They also may decline in price even though in theory they are already undervalued. o Foreign investment risk. Special risks associated with investments in foreign companies include exposure to currency fluctuations, less liquidity, less developed or less efficient trading markets, lack of comprehensive company information, political instability and differing auditing and legal standards. Emerging markets tend to be more volatile and less liquid than the markets of more mature economies, and generally have less diverse and less mature economic structures and less stable political systems than those of developed countries. o Non-diversification risk. The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.</pre>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, Narrative33false0rr_RiskLoseMoneyrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The fund's share price fluctuates, sometimes dramatically, which means you could lose money.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringSummarize the principal risks of investing in the Fund, including the risks to which the Fund's portfolio as a whole is subject and the circumstances reasonably likely to affect adversely the Fund's net asset value, yield, and total return. Unless the Fund is a Money Market Fund, disclose that loss of money is a risk of investing in the Fund. 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 -Subsection b falsefalseRisk, Lose Money34false0rr_RiskNondiversifiedStatusrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringIf applicable, state that the Fund is non-diversified, describe the effect of non-diversification (e.g., disclose that, compared with other funds, the Fund may invest a greater percentage of its assets in a particular issuer), and summarize the risks of investing in a non-diversified fund.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph iv -Subsection b falsefalseRisk, Nondiversified Status35false0rr_RiskNotInsuredDepositoryInstitutionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00An investment in the fund is not a bank deposit. It is not insured or guaranteed by the FDIC or any other government agency.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringIf the Fund is advised by or sold through an insured depository institution, state that An investment in the Fund is not a deposit of the bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. A Money Market Fund that is advised by or sold through an insured depository institution should combine the disclosure required by Items 2(c)(1)(ii) and (iii) in a single statement.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph iii -Subsection b falsefalseRisk, Not Insured Depository Institution36false0rr_BarChartAndPerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PerformancefalsefalsefalsefalsefalseOtherxbrli: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, Heading37false0rr_PerformanceNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The following bar chart and table provide some indication of the risks of investing in the fund. The table compares the average annual total returns of the fund's shares to those of a broad measure of market performance. The fund's past performance (before and after taxes) is no guarantee of future results. More recent performance information may be available at www.dreyfus.com.</pre>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, Narrative38false0rr_PerformanceInformationIllustratesVariabilityOfReturnsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The following bar chart and table provide some indication of the risks of investing in the fund.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInclude the bar chart and table required by paragraphs (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides 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). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalsePerformance, Information Illustrates Variability of Returns39false0rr_PerformanceAvailabilityWebSiteAddressrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00www.dreyfus.comfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringIf applicable, include a statement explaining that updated performance information is available and providing a Website address and/or toll-free (or collect) telephone number where the updated information may be obtained.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalsePerformance, Availability Website Address40false0rr_PerformancePastDoesNotIndicateFuturerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The fund's past performance (before and after taxes) is no guarantee of future results.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInclude the bar chart and table required by paragraphs (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides 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). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalsePerformance, Past Does Not Indicate Future41false0rr_BarChartNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The bar chart shows changes in the performance of the fund's Class A shares from year to year. Sales charges, if any, are not reflected in the bar chart, and if those charges were included, returns would have been less than those shown.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringProvide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides 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). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalseBar Chart, Narrative42false0rr_BarChartDoesNotReflectSalesLoadsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Sales charges, if any, are not reflected in the bar chart, and if those charges were included, returns would have been less than those shown.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInclude the bar chart and table required by Item 4 (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides 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). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Provide annual total returns beginning with the earliest calendar year. Calculate annual returns using the Instructions to Item 8(a), except that the calculations should be based on calendar years. If a Fund's shares are sold subject to a sales load or account fees, state that sales loads or account fees are not reflected in the bar chart and that, if these amounts were reflected, returns would be less than those shown.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalseBar Chart, Does Not Reflect Sales Loads43false0rr_AnnualReturnCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Year-by-Year Total Returns as of 12/31 each year (%) Class A Shares falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringIf 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. Provide annual total returns beginning with the earliest calendar year. Calculate annual returns using the Instructions to Item 8(a), except that the calculations should be based on calendar years. If a Fund's shares are sold subject to a sales load or account fees, state that sales loads or account fees are not reflected in the bar chart and that, if these amounts were reflected, returns would be less than those shown. 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). When a Multiple Class Fund offering one or more Classes offers a new Class in a prospectus that does not offer the shares of any other Class, include the bar chart with annual total returns for any other existing Class for the first year that the Class is offered. Explain in a footnote that the returns are for a Class that is not offered in the prospectus that would have substantially similar annual returns because the shares are invested in the same portfolio of securities and the annual returns would differ only to the extent that the Classes do not have the same expenses. Include return information for the other Class reflected in the bar chart in the performance table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit b -Subsection b falsefalseAnnual Return, Caption44false0rr_BarChartClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>Best Quarter Q2, 2008: 27.43% Worst Quarter Q3, 2008: -38.26%</pre>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, Closing45false0rr_PerformanceTableNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>After-tax performance is shown only for Class A shares. After-tax performance of the fund's other share classes will vary. After-tax returns are calculated using the historical highest individual federal marginal tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.</pre>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, _____). For a Fund that provides annual total returns for only one calendar year or for a Fund that does not include the bar chart because it does not have annual returns for a full calendar year, modify, as appropriate, the narrative explanation required by paragraph (c)(2)(i) (e.g., by stating that the information gives some indication of the risks of an investment in the Fund by comparing the Fund's performance with a broad measure of market performance).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iv -Subsection b falsefalsePerformance Table, Narrative46false0rr_AverageAnnualReturnCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Average Annual Total Returns (as of 12/31/10)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 5 -Subsection b falsefalseAverage Annual Returns, Caption47false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse3falsefalseUSDtruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_ProspectusShareClassAxis} : Dreyfus Natural Resources Fund - Class A 1/28/2010 - 1/28/2011 USD ($) $eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429423x-9996663http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseDreyfus Natural Resources Fund - Class Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_C000004623Memberrr_ProspectusShareClassAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170pureStandardhttp://www.xbrl.org/2003/instancepure0USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | Dreyfus Natural Resources Fund - Class A48true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:49false0dei_TradingSymboldeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00DNLAXfalsefalsefalsefalsefalseOtherxbrli:normalizedStringItemTypenormalizedstringTrading symbol of an instrument as listed on an exchange.No authoritative reference available.falsefalseTrading Symbol50false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05750.0575falsefalsefalsefalsefalseOtherrr: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 price)51false0rr_MaximumDeferredSalesChargeOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000[1]falsefalsefalsefalsefalseOtherrr: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 deferred sales charge (load) (as a percentage of lower of purchase or sale price)52false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00750.0075falsefalsefalsefalsefalseOtherrr: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 fees53false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsefalsefalseOtherrr: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 (Rule 12b-1) fees54false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01040.0104falsefalsefalsefalsefalseOtherrr: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 falsefalseOther expenses (including shareholder services fees)55false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01790.0179falsefalsefalsefalsefalseOtherrr: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 falsefalseTotal annual fund operating expenses56false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue746746falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 1 Year57false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue11061106falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 3 Years58false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue14891489falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 5 Years59false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue25592559falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 10 Years60false0rr_ExpenseExampleNoRedemptionYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue746746falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 1 Year61false0rr_ExpenseExampleNoRedemptionYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue11061106falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 3 Years62false0rr_ExpenseExampleNoRedemptionYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue14891489falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 5 Years63false0rr_ExpenseExampleNoRedemptionYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue25592559falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 10 Years64false0rr_AnnualReturn2004rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.28000.2800falsefalsefalsefalsefalseOtherxbrli: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 200465false0rr_AnnualReturn2005rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.34790.3479falsefalsefalsefalsefalseOtherxbrli: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 200566false0rr_AnnualReturn2006rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.12080.1208falsefalsefalsefalsefalseOtherxbrli: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 200667false0rr_AnnualReturn2007rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.43750.4375falsefalsefalsefalsefalseOtherxbrli: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 200768false0rr_AnnualReturn2008rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.4989-0.4989falsefalsefalsefalsefalseOtherxbrli: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 200869false0rr_AnnualReturn2009rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.42350.4235falsefalsefalsefalsefalseOtherxbrli: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 200970false0rr_AnnualReturn2010rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.20490.2049falsefalsefalsefalsefalseOtherxbrli: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 201071false0rr_HighestQuarterlyReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Best QuarterfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringIf 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 falsefalseHighest Quarterly Return, Label72false0rr_BarChartHighestQuarterlyReturnDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002008-06-30falsefalsetruefalsefalseOtherxbrli:dateItemTypedateIf 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 falsefalseHighest Quarterly Return, Date73false0rr_BarChartHighestQuarterlyReturnrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.27430.2743falsefalsefalsefalsefalseOtherxbrli: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.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseHighest Quarterly Return74false0rr_LowestQuarterlyReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Worst QuarterfalsefalsefalsefalsefalseOtherxbrli:stringItemTypestringIf 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 falsefalseLowest Quarterly Return, Label75false0rr_BarChartLowestQuarterlyReturnDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002008-09-30falsefalsetruefalsefalseOtherxbrli:dateItemTypedateIf 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 falsefalseLowest Quarterly Return, Date76false0rr_BarChartLowestQuarterlyReturnrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.3826-0.3826falsefalsefalsefalsefalseOtherxbrli: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.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseLowest Quarterly Return77false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Class A returns before taxesfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label78false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.13570.1357falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year79false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05470.0547falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years80false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.14230.1423falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception81false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date82false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse4falsefalsetruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_ProspectusShareClassAxis} : Dreyfus Natural Resources Fund - Class A {rr_PerformanceMeasureAxis} : After Taxes on Distributions 1/28/2010 - 1/28/2011 eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429423x-9996663_429555x429511http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseDreyfus Natural Resources Fund - Class Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_C000004623Memberrr_ProspectusShareClassAxisexplicitMemberfalsefalseAfter Taxes on Distributionsrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsMemberrr_PerformanceMeasureAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | Dreyfus Natural Resources Fund - Class A | After Taxes on Distributions83true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:84false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Class A returns after taxes on distributionsfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label85false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.13570.1357falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year86false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05080.0508falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years87false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.13510.1351falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception88false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date89false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse5falsefalsetruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_ProspectusShareClassAxis} : Dreyfus Natural Resources Fund - Class A {rr_PerformanceMeasureAxis} : After Taxes on Distributions and Sales 1/28/2010 - 1/28/2011 eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429423x-9996663_429555x429483http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseDreyfus Natural Resources Fund - Class Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_C000004623Memberrr_ProspectusShareClassAxisexplicitMemberfalsefalseAfter Taxes on Distributions and Salesrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsAndSalesMemberrr_PerformanceMeasureAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | Dreyfus Natural Resources Fund - Class A | After Taxes on Distributions and Sales90true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:91false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Class A returns after taxes on distributions and sale of fund sharesfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label92false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.08820.0882falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year93false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.04680.0468falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years94false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.12400.1240falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception95false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date96false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse6falsefalseUSDtruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_ProspectusShareClassAxis} : Dreyfus Natural Resources Fund - Class B 1/28/2010 - 1/28/2011 USD ($) $eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429423x-9996662http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseDreyfus Natural Resources Fund - Class Brr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_C000004624Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | Dreyfus Natural Resources Fund - Class B97true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:98false0dei_TradingSymboldeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00DLDBXfalsefalsefalsefalsefalseOtherxbrli:normalizedStringItemTypenormalizedstringTrading symbol of an instrument as listed on an exchange.No authoritative reference available.falsefalseTrading Symbol99false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsefalsefalseOtherrr: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 price)100false0rr_MaximumDeferredSalesChargeOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.04000.0400falsefalsefalsefalsefalseOtherrr: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 deferred sales charge (load) (as a percentage of lower of purchase or sale price)101false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00750.0075falsefalsefalsefalsefalseOtherrr: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 fees102false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00750.0075falsefalsefalsefalsefalseOtherrr: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 (Rule 12b-1) fees103false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01090.0109falsefalsefalsefalsefalseOtherrr: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 falsefalseOther expenses (including shareholder services fees)104false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.02590.0259falsefalsefalsefalsefalseOtherrr: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 falsefalseTotal annual fund operating expenses105false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue662662falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 1 Year106false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue11051105falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 3 Years107false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue15751575falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 5 Years108false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue25512551falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 10 Years109false0rr_ExpenseExampleNoRedemptionYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue262262falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 1 Year110false0rr_ExpenseExampleNoRedemptionYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue805805falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 3 Years111false0rr_ExpenseExampleNoRedemptionYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue13751375falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 5 Years112false0rr_ExpenseExampleNoRedemptionYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue25512551falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 10 Years113false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Class B returns before taxesfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label114false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.15520.1552falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year115false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05560.0556falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years116false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.14440.1444falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception117false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date118false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse7falsefalseUSDtruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_ProspectusShareClassAxis} : Dreyfus Natural Resources Fund - Class C 1/28/2010 - 1/28/2011 USD ($) $eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429423x-9996661http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseDreyfus Natural Resources Fund - Class Crr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_C000004625Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | Dreyfus Natural Resources Fund - Class C119true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:120false0dei_TradingSymboldeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00DLDCXfalsefalsefalsefalsefalseOtherxbrli:normalizedStringItemTypenormalizedstringTrading symbol of an instrument as listed on an exchange.No authoritative reference available.falsefalseTrading Symbol121false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsefalsefalseOtherrr: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 price)122false0rr_MaximumDeferredSalesChargeOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01000.0100falsefalsefalsefalsefalseOtherrr: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 deferred sales charge (load) (as a percentage of lower of purchase or sale price)123false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00750.0075falsefalsefalsefalsefalseOtherrr: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 fees124false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00750.0075falsefalsefalsefalsefalseOtherrr: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 (Rule 12b-1) fees125false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01050.0105falsefalsefalsefalsefalseOtherrr: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 falsefalseOther expenses (including shareholder services fees)126false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.02550.0255falsefalsefalsefalsefalseOtherrr: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 falsefalseTotal annual fund operating expenses127false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue358358falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 1 Year128false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue793793falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 3 Years129false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue13551355falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 5 Years130false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue28852885falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 10 Years131false0rr_ExpenseExampleNoRedemptionYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue258258falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 1 Year132false0rr_ExpenseExampleNoRedemptionYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue793793falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 3 Years133false0rr_ExpenseExampleNoRedemptionYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue13551355falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 5 Years134false0rr_ExpenseExampleNoRedemptionYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue28852885falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 10 Years135false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Class C returns before taxesfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label136false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.18600.1860falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year137false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05940.0594falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years138false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.14340.1434falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception139false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date140false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse8falsefalseUSDtruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_ProspectusShareClassAxis} : Dreyfus Natural Resources Fund - Class I 1/28/2010 - 1/28/2011 USD ($) $eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429423x-9996660http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseDreyfus Natural Resources Fund - Class Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_C000004626Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | Dreyfus Natural Resources Fund - Class I141true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:142false0dei_TradingSymboldeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00DLDRXfalsefalsefalsefalsefalseOtherxbrli:normalizedStringItemTypenormalizedstringTrading symbol of an instrument as listed on an exchange.No authoritative reference available.falsefalseTrading Symbol143false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsefalsefalseOtherrr: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 price)144false0rr_MaximumDeferredSalesChargeOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsefalsefalseOtherrr: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 deferred sales charge (load) (as a percentage of lower of purchase or sale price)145false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00750.0075falsefalsefalsefalsefalseOtherrr: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 fees146false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsefalsefalseOtherrr: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 (Rule 12b-1) fees147false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00750.0075falsefalsefalsefalsefalseOtherrr: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 falsefalseOther expenses (including shareholder services fees)148false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01500.0150falsefalsefalsefalsefalseOtherrr: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 falsefalseTotal annual fund operating expenses149false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue153153falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 1 Year150false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue474474falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 3 Years151false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue818818falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 5 Years152false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue17911791falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, With Redemption, 10 Years153false0rr_ExpenseExampleNoRedemptionYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue153153falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 1 Year154false0rr_ExpenseExampleNoRedemptionYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue474474falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 3 Years155false0rr_ExpenseExampleNoRedemptionYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue818818falsefalsefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 5 Years156false0rr_ExpenseExampleNoRedemptionYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue17911791falsetruefalsefalsefalseMonetaryrr: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 falsefalseExpense Example, No Redemption, 10 Years157false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Class I returns before taxesfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label158false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.20930.2093falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year159false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.07020.0702falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years160false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.15510.1551falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception161false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date162false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse9falsefalsetruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_PerformanceMeasureAxis} : S&P 500 Index 1/28/2010 - 1/28/2011 eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429555x-9998778http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseS&P 500 Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_RRINDEX00001Memberrr_PerformanceMeasureAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | S&P 500 Index163true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:164false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00S&P 500® Index reflects no deduction for fees, expenses or taxesfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label165false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.15080.1508falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year166false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.02290.0229falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years167false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.04630.0463falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception168false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date169false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://xbrl.sec.gov/rr/role/riskreturndetaildata1falsefalsefalse00falsefalsefalsefalsefalse10falsefalsetruefalse{dei_LegalEntityAxis} : Dreyfus Natural Resources Fund {rr_PerformanceMeasureAxis} : S&P North American Natural Resources Sector Index 1/28/2010 - 1/28/2011 eol_0001111178-11-000004_STD_366_20110128_0_396770x-9996659_429555x-9998694http://www.sec.gov/CIK0001111178duration2010-01-28T00:00:002011-01-28T00:00:00falsefalseDreyfus Natural Resources Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_S000001720Memberdei_LegalEntityAxisexplicitMemberfalsefalseS&P North American Natural Resources Sector Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldick0001111178_RRINDEX00002Memberrr_PerformanceMeasureAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0OthernaNo definition available.No authoritative reference available.falsefalseDreyfus Natural Resources Fund | S&P North American Natural Resources Sector Index170true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:171false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00S&P North American Natural Resources Sector Index reflects no deduction for fees, expenses or taxesfalsefalsefalsefalsefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalseAverage Annual Returns, Label172false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.23880.2388falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 1 Year173false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.08990.0899falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, 5 Years174false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.16640.1664falsefalsefalsefalsefalseOtherxbrli: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 falsefalseAverage Annual Returns, Since Inception175false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002003-10-31falsefalsetruefalsefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseAverage Annual Returns, Inception Date1Class A shares bought without an initial sales charge as part of an investment of $1 million or more may be charged a deferred sales charge of 1.00% if redeemed within one year.1174Risk/Return Detail Data (USD $)NoRoundingUnKnownUnKnownUnKnowntruetrue