Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Apr. 29, 2011
Morgan Stanley US Government Securities Trust (Prospectus Summary): \| Morgan Stanley US Government Securities Trust
Risk/Return:	rr_RiskReturnAbstract
Supplement Text	ck0000730044_SupplementTextBlock	Morgan Stanley June 13, 2011 Supplement SUPPLEMENT DATED JUNE 13, 2011 TO THE PROSPECTUS OF MORGAN STANLEY U.S. GOVERNMENT SECURITIES TRUST Dated April 29, 2011 The following disclosure is hereby added as the last sentence of the second paragraph in the section of the Prospectus titled "Fund Summary—Principal Investment Strategies": The Fund may invest in restricted and illiquid securities. The following disclosure is hereby added as the fifth paragraph under the section of the Prospectus titled "Fund Summary—Principal Risks": *Liquidity Risk.* The Fund's investments in restricted and illiquid securities may entail greater risk than investments in publicly traded securities. These securities may be more difficult to sell, particularly in times of market turmoil. Illiquid securities may be more difficult to value. If the Fund is forced to sell an illiquid security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss. PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE. USGSPT 6/11
Investment Strategy, Heading	rr_StrategyHeading	The following disclosure is hereby added as the last sentence of the second paragraph in the section of the Prospectus titled "Fund Summary—Principal Investment Strategies":
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund may invest in restricted and illiquid securities.
Risk, Heading	rr_RiskHeading	The following disclosure is hereby added as the fifth paragraph under the section of the Prospectus titled "Fund Summary—Principal Risks":
Risk, Narrative	rr_RiskNarrativeTextBlock	*Liquidity Risk.* The Fund's investments in restricted and illiquid securities may entail greater risk than investments in publicly traded securities. These securities may be more difficult to sell, particularly in times of market turmoil. Illiquid securities may be more difficult to value. If the Fund is forced to sell an illiquid security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss.
Morgan Stanley US Government Securities Trust \| A
Risk/Return:	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	USGAX
Morgan Stanley US Government Securities Trust \| B
Risk/Return:	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	USGBX
Morgan Stanley US Government Securities Trust \| C
Risk/Return:	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	USGCX
Morgan Stanley US Government Securities Trust \| I
Risk/Return:	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	USGDX

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The date of the prospectus.

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Narrative Risk Disclosure.

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Narrative 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.

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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.

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