Label	Element	Value
MORGAN STANLEY US GOVERNMENT MONEY MARKET TRUST
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	ck0000356409_SupplementTextBlock	JULY 26, 2017 Supplement SUPPLEMENT DATED JULY 26, 2017 TO THE SUMMARY PROSPECTUS AND PROSPECTUS OF Morgan Stanley U.S. Government Money Market Trust, dated May 31, 2017 (the "Fund")
Risk/Return [Heading]	rr_RiskReturnHeading	MORGAN STANLEY US GOVERNMENT MONEY MARKET TRUST
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The Fund's Adviser, Morgan Stanley Investment Management Inc., has agreed to waive the Fund's advisory fee to the extent that such fee on an annualized basis exceeds 0.15% of the average daily net assets of the Fund, effective August 1, 2017. This fee waiver will continue for at least one year or until such time as the Fund's Board of Trustees acts to discontinue all or a portion of such waiver when it deems such action is appropriate. Please retain this supplement for future reference.

This table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown. The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection instructions
-Paragraph 1
-Subparagraph b

Name:	rr_ExpenseNarrativeTextBlock
Namespace Prefix:	rr_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration