Label	Element	Value
Opportunistic Small Cap Portfolio
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	ck0000813383_SupplementTextBlock	DREYFUSVARIABLE INVESTMENT FUND - Opportunistic Small Cap Portfolio Supplement to Summary and Statutory Prospectuses dated May 1, 2013 IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY
Risk/Return [Heading]	rr_RiskReturnHeading	Opportunistic Small Cap Portfolio
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Effective on or about October 1, 2013, the following information will supersede and replace the second sentence of the first paragraph in “Principal Investment Strategy” in the summary prospectus and “Fund Summary – Principal Investment Strategy” in the prospectus and the third and fourth sentences of the first paragraph in “Fund Details – Goal and Approach” in the prospectus: The fund currently considers small cap companies to be those companies with market capitalizations that fall within the range of $50 million and $4 billion.The fund may invest up to 20% of its net assets in securities not considered to be small 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

-Name Form

-Number N-1A

-Chapter A

-Section 4

-Subsection a

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