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Midcap Stock Portfolio
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Supplement [Text Block]	ck0001056707_SupplementTextBlock	July 19, 2013 DREYFUS INVESTMENT PORTFOLIOS - MidCap Stock Portfolio Supplement to Summary and Statutory Prospectuses dated May 1, 2013 IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY
Risk/Return [Heading]	rr_RiskReturnHeading	Midcap Stock Portfolio
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Effective on or about October 1, 2013, the following information will supplement the “Principal Investment Strategy” in the Summary prospectus and “Fund Summary –Principal Investment Strategy” and “Fund Details – Goal and Approach” sections in the prospectus: The fund currently considers mid-cap companies to be those companies with market capitalizations that fall within the range of $400 million and $29 billion. The fund may invest up to 20% of its net assets in securities not considered to be mid-cap companies.

Principal 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

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-Number N-1A

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-Section 4

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