Document and Entity Information	0 Months Ended
	Jan. 31, 2013
Risk/Return:
Document Type	485BPOS
Document Period End Date	Jan. 31, 2013
Registrant Name	MORGAN STANLEY US GOVERNMENT MONEY MARKET TRUST
Central Index Key	0000356409
Amendment Flag	false
Document Creation Date	May 31, 2013
Document Effective Date	May 31, 2013
Prospectus Date	May 31, 2013
MORGAN STANLEY US GOVERNMENT MONEY MARKET TRUST | MORGAN STANLEY US GOVERNMENT MONEY MARKET TRUST
Risk/Return:
Trading Symbol	DWGXX