XML 10 R2.htm IDEA: XBRL DOCUMENT v3.25.1
Shareholder Report
 6 Months Ended
Feb. 28, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name Vanguard Money Market Reserves
Entity Central Index Key 0000106830
Entity Investment Company Type N-1A
Document Period End Date Feb. 28, 2025
C000012240  
Shareholder Report [Line Items]  
Fund Name Cash Reserves Federal Money Market Fund
Class Name Admiral™ Shares
Trading Symbol VMRXX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Cash Reserves Federal Money Market Fund (the "Fund") for the period of September 1, 2024, to February 28, 2025.
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature. You can also request this information by contacting us at 800-662-7447.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Share Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Admiral Shares
$5
0.10%Footnote Reference1
FootnoteDescription
Footnote1
Annualized.
Expenses Paid, Amount $ 5
Expense Ratio, Percent 0.10%
AssetsNet $ 122,578,000,000
Holdings Count | Holding 298
Additional Fund Statistics [Text Block]

Fund Statistics

(as of February 28, 2025)

Fund Net Assets (in millions)
$122,578
Number of Portfolio Holdings
298
Holdings [Text Block]

This table reflects the Fund's investments, including short-term investments and other assets and liabilities.

Distribution by Effective Maturity % of Net Assets

(as of February 28, 2025)

1 to 7 Days
56.9%
8 to 30 Days
13.7%
31 to 60 Days
15.0%
61 to 90 Days
8.3%
91 to 180 Days
5.7%
Over 180 Days
1.5%
Other Assets and Liabilities—Net
(1.1%)
Material Fund Change [Text Block]
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000012238  
Shareholder Report [Line Items]  
Fund Name Federal Money Market Fund
Class Name Investor Shares
Trading Symbol VMFXX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Federal Money Market Fund (the "Fund") for the period of September 1, 2024, to February 28, 2025.
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature. You can also request this information by contacting us at 800-662-7447.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Share Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Shares
$6
0.11%Footnote Reference1
FootnoteDescription
Footnote1
Annualized.
Expenses Paid, Amount $ 6
Expense Ratio, Percent 0.11%
AssetsNet $ 344,324,000,000
Holdings Count | Holding 297
Additional Fund Statistics [Text Block]

Fund Statistics

(as of February 28, 2025)

Fund Net Assets (in millions)
$344,324
Number of Portfolio Holdings
297
Holdings [Text Block]

This table reflects the Fund's investments, including short-term investments and other assets and liabilities.

Distribution by Effective Maturity % of Net Assets

(as of February 28, 2025)

1 to 7 Days
59.8%
8 to 30 Days
13.2%
31 to 60 Days
14.8%
61 to 90 Days
7.4%
91 to 180 Days
4.9%
Over 180 Days
1.1%
Other Assets and Liabilities—Net
(1.2%)
Material Fund Change [Text Block]
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature