2.4.0.8020000 - Document - Risk/Return Summary {Unlabeled} - Dreyfus Mid-Cap Growth Fundfalsefalsefalse1false falsefalseS000000571Memberhttp://www.sec.gov/CIK0000038403duration2013-07-25T00:00:002013-07-25T00:00:001false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00Dreyfus Mid-Cap Growth Fundfalsefalsefalse1false truefalseS000000571Memberhttp://www.sec.gov/CIK0000038403duration2013-07-25T00:00:002013-07-25T00:00:00falsefalseDreyfus Mid-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000038403_S000000571Memberdei_LegalEntityAxisexplicitMembernanafalse0Dreyfus Mid-Cap Growth Fund2false 4rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Dreyfus Mid-Cap Growth Fundfalsefalsefalsexbrli: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 false0Risk/Return [Heading]3false 4ck0000038403_SupplementTextBlockck0000038403_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 July 25, 2013 DREYFUS FUNDS, INC. -          Dreyfus Mid-Cap Growth Fund Supplement to Summary Prospectus dated May 21, 2013 and Statutory Prospectus dated May 1, 2013 As revised, May 21, 2013 IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY falsefalsefalsenonnum:textBlockItemTypenaNo authoritative reference available.No definition available.false0Supplement [Text Block]4false 4rr_StrategyNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 Effective on or about October 1, 2013, the following information will supersede and replace the first sentence of the first paragraph in “Principal Investment Strategy” in the summary prospectus and “Fund Summary - Principal Investment Strategy” in the prospectus and the second through eight sentences of the first paragraph in “Fund Details - Goal and Approach” in the prospectus: To pursue its goal, the fund normally invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities of companies with market capitalizations that fall within the range of $500 million and $20 billion (i.e., mid-cap companies).  The fund may invest up to 20% of its net assets in securities not considered to be mid-cap companies. falsefalsefalsenonnum:textBlockItemTypenaPrincipal 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a false0Strategy Narrative [Text Block]falseRisk/Return Summary - Dreyfus Mid-Cap Growth Fund (Dreyfus Mid-Cap Growth Fund)UnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://dreyfus.com/20130725/role/DocumentRiskReturnSummaryUnlabeledDreyfusMidCapGrowthFund14