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Shareholder Report
 12 Months Ended
Jan. 31, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSR
Amendment Flag false
Registrant Name Morgan Stanley U.S. Government Money Market Trust
Entity Central Index Key 0000356409
Entity Investment Company Type N-1A
Document Period End Date Jan. 31, 2025
C000011343  
Shareholder Report [Line Items]  
Fund Name Morgan Stanley U.S. Government Money Market Trust
Class Name R
Trading Symbol DWGXX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about Morgan Stanley U.S. Government Money Market Trust for the period of February 1, 2024 to January 31, 2025.
Shareholder Report Annual or Semi-Annual Annual Shareholder Report
Additional Information [Text Block] You can find additional information about the Fund at www.morganstanley.com/im/shareholderreports. You can also request this information by contacting us at 1-800-869-6397.
Additional Information Phone Number 1-800-869-6397
Additional Information Website <span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: left;">www.morganstanley.com/im/shareholderreports</span>
Expenses [Text Block]

What were the Fund costs for the last year?

(based on a hypothetical $10,000 investment)

Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Class R
$36
0.35%
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.35%
AssetsNet $ 1,085,484,801
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 1,539,299
Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets
$1,085,484,801
# of Portfolio Holdings
130
Total Advisory Fees Paid
$1,539,299
Holdings [Text Block]

Asset Allocation (% of total investments)

Credit Rating Chart
Value
Value
U.S. Agency Securities
11.8%
U.S. Treasury Securities
41.0%
Repurchase Agreements
47.2%

Maturity Schedule (% of total investments)

Group By Asset Type Chart
Value
Value
121+ Days
11.5%
91 - 120 Days
6.8%
61 - 90 Days
7.5%
31 - 60 Days
5.5%
1 - 30 Days
68.7%
Material Fund Change [Text Block]
Updated Prospectus Web Address <span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: left;">www.morganstanley.com/im/shareholderreports</span>
C000171230  
Shareholder Report [Line Items]  
Fund Name Morgan Stanley U.S. Government Money Market Trust
Class Name S
Trading Symbol DGEXX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about Morgan Stanley U.S. Government Money Market Trust for the period of February 1, 2024 to January 31, 2025.
Shareholder Report Annual or Semi-Annual Annual Shareholder Report
Additional Information [Text Block] You can find additional information about the Fund at www.morganstanley.com/im/shareholderreports. You can also request this information by contacting us at 1-800-869-6397.
Additional Information Phone Number 1-800-869-6397
Additional Information Website <span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: left;">www.morganstanley.com/im/shareholderreports</span>
Expenses [Text Block]

What were the Fund costs for the last year?

(based on a hypothetical $10,000 investment)

Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Class S
$36
0.35%
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.35%
AssetsNet $ 1,085,484,801
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 1,539,299
Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets
$1,085,484,801
# of Portfolio Holdings
130
Total Advisory Fees Paid
$1,539,299
Holdings [Text Block]

Asset Allocation (% of total investments)

Credit Rating Chart
Value
Value
U.S. Agency Securities
11.8%
U.S. Treasury Securities
41.0%
Repurchase Agreements
47.2%

Maturity Schedule (% of total investments)

Group By Asset Type Chart
Value
Value
121+ Days
11.5%
91 - 120 Days
6.8%
61 - 90 Days
7.5%
31 - 60 Days
5.5%
1 - 30 Days
68.7%
Material Fund Change [Text Block]
Updated Prospectus Web Address <span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: left;">www.morganstanley.com/im/shareholderreports</span>