Label	Element	Value
Class X Prospectus \| INCOME PLUS PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	ck0000716716_SupplementTextBlock	Morgan Stanley June 18, 2018 Supplement SUPPLEMENT DATED JUNE 18, 2018 TO THE PROSPECTUS OF MORGAN STANLEY VARIABLE INVESTMENT SERIES THE INCOME PLUS PORTFOLIO CLASS X Dated April 30, 2018
Risk/Return [Heading]	rr_RiskReturnHeading	INCOME PLUS PORTFOLIO
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The following is hereby added as the sixth paragraph of the section of the Prospectus entitled "Fund Summary—Principal Investment Strategies": The Fund's investment process incorporates information about environmental, social and governance issues (also referred to as ESG) via an integrated approach within the investment team's fundamental investment analysis framework. The Fund's Adviser may engage with management of certain issuers regarding corporate governance practices as well as what the Fund's Adviser deems to be materially important environmental and/or social issues facing a company. PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE.

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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Balance Type:	na
Period Type:	duration