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      id="x_1929dda7-2836-4888-b45a-7ff23d65b0e7">&lt;span style="color:#000000;font-family:Arial;font-size:13pt;font-weight:bold;"&gt;Vanguard Cash Reserves Federal Money Market Fund&lt;/span&gt;</oef:RiskReturnHeading>
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      id="x_55bf01d4-6ff0-47ae-b4d8-3daa83fee213">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Investment Objective&lt;/span&gt;</oef:ObjectiveHeading>
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      id="c3b12164-1556-43f3-a8f3-aa37dff4a98a">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Vanguard Cash Reserves Federal Money Market Fund (the &#x201c;Fund&#x201d;) seeks to provide current income while maintaining liquidity and a stable share price of $1.&lt;/span&gt;</oef:ObjectivePrimaryTextBlock>
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      id="x_46de9617-d348-4a61-903a-eb5a04c50757">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Fees and Expenses&lt;/span&gt;</oef:ExpenseHeading>
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      id="d02f6eec-82c8-4b75-9f00-87bf3f0a9412">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The following tables describe the fees and expenses you may pay if you buy, hold, and sell shares of the Fund. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.&lt;/span&gt;</oef:ExpenseNarrativeTextBlock>
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      id="x_32fc4ef0-10df-453c-b3f9-726e922e7aee">&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;font-weight:bold;"&gt;Shareholder Fees&lt;/span&gt;
&lt;br/&gt;&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;"&gt;(Fees paid directly from your investment)&lt;/span&gt;</oef:ShareholderFeesCaption>
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      id="x_256da73d-9e7e-497f-9739-f64ab4951edc">&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;font-weight:bold;"&gt;Annual Fund Operating Expenses&lt;/span&gt;
&lt;br/&gt;&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;"&gt;(Expenses that you pay each year as a percentage of the value of your investment)&lt;/span&gt;</oef:OperatingExpensesCaption>
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      id="x_6b6055a7-8f72-4e57-a4df-a87556aa8f9c">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Example&lt;/span&gt;</oef:ExpenseExampleHeading>
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      id="x_4edf0a29-64fe-43d3-a21f-739d2ce4454e">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund&#x2019;s operating expenses remain the same.&lt;/span&gt;</oef:ExpenseExampleNarrativeTextBlock>
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      decimals="INF"
      id="x_8faf3890-346f-443e-a914-ad95c420eb3a"
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      decimals="INF"
      id="d09e933d-9928-4de8-8363-9f95b51241d7"
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    <oef:ExpenseExampleYear10
      contextRef="RetailProspectusMember_S000004463_C000012240"
      decimals="INF"
      id="f48a6900-c695-4b4a-bbe6-5bf070e0d256"
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    <oef:StrategyHeading
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      id="x_4ebf2929-f12b-47f5-a210-ca8b96aa3ccf">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Principal Investment Strategies&lt;/span&gt;</oef:StrategyHeading>
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      id="x_2e4a8a35-f6b9-48b2-a08b-3128d293274e">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The Fund employs an active management approach, investing primarily in high-quality, short-term money market instruments. Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in securities issued by the U.S. government and its agencies and instrumentalities, which includes repurchase agreements that are collateralized solely by U.S. government securities or by cash.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;line-height:11.5pt;"&gt;The Fund has elected to operate as a government money market fund under Rule 2a-7 of the Investment Company Act of 1940, as amended. Government money market funds are required to invest at least 99.5% of their total assets in cash, U.S. government securities, and/or repurchase agreements that are collateralized solely by U.S. government securities or by cash. The Fund generally invests 100% of its assets in U.S. government securities (including repurchase agreements) and therefore satisfies the requirement for designation as a government money market fund. The Fund seeks to maintain a stable share price, or net asset value (NAV), of $1; maintains a dollar-weighted average maturity of 60 days or less and a dollar-weighted average life of 120 days or less; and invests in high-quality securities with effective maturities of 397 days or less. To be eligible for investment by the Fund, a security must be determined by methods approved by the board of trustees of Vanguard Money Market Reserves to present minimal credit risk. As a result, the Fund selects securities based in part on a consideration of maturity, portfolio diversification, portfolio liquidity, and credit quality. Some of the securities held by the Fund, while still considered high quality, are neither guaranteed by the U.S. Treasury nor supported by the full faith and credit of the U.S. government. Securities held by the Fund may pay fixed, variable, or floating rates of interest.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;line-height:11.5pt;"&gt;As a matter of fundamental policy, the Fund concentrates (i.e., invests more than 25% of) its assets in the securities of issuers whose principal business activities are in the financial services industry, which includes, without limitation, securities issued by certain government-sponsored enterprises.&lt;/span&gt;</oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="RetailProspectusMember_S000004463_RiskLoseMoneyMember"
      id="x_3c3673e7-7657-4f1f-ae17-152470c39612">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;As with any investment, an investment in the Fund could lose money over any time period.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;You could lose money by investing in the Fund.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="RetailProspectusMember_S000004463_GeneralMarketRiskMember"
      id="aaafc02d-b903-4138-b28f-0620ac9de596">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;General Market Risk.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The markets in which the Fund invests can be affected by a variety of factors. These factors, which can be real or perceived, may include economic, market, political, and regulatory conditions and developments as well as local, regional, or global events such as wars, military conflicts, natural disasters, and public health issues. In addition, investor sentiment and expectations regarding these factors can also impact the markets. Different parts of the market, including different industries and &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:0.0pt;"&gt;sectors as well as different types of securities, may react differently to factors that affect the market. These factors can contribute to market uncertainty, market volatility, and fluctuations in the value of the Fund&#x2019;s investments, thereby resulting in potential losses to the Fund over short or long periods.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004463_InvestingInBondMarketsRiskMember"
      id="x_10e55382-0c27-44da-8179-243e374a7eca">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Investing in Bond Markets&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund invests in money market instruments, which are high quality, short-term debt securities. As a result, the Fund may be impacted by the general condition of the bond markets and by factors that affect bonds and bond issuers. For example, as a general rule, bond prices and interest rates move in opposite directions. When interest rates rise, bond prices tend to fall, and when interest rates fall, bond prices tend to go up. Bond income also is affected by changes in interest rates. Interest rates can rise or fall for a number of reasons, including, but not limited to, central bank monetary policy, inflationary or deflationary pressures, and changes in general market and economic conditions. Changing interest rates, including, but not limited to, rates that fall below zero, could have unpredictable effects on the overall market and may expose the bond markets in particular to heightened volatility and potential illiquidity. The degree to which the Fund is impacted by certain bond market risks may vary based on factors disclosed in its principal investment strategies, such as the types of bonds in which it invests and the overall credit quality, average maturity, and/or average duration of its bond holdings.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="RetailProspectusMember_S000004463_StableNAVRiskMember"
      id="x_44a59883-6f37-41cc-8044-e7e6071347b6">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Stable NAV&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;. There can be no assurance that the Fund will be successful in maintaining a stable NAV. A wide variety of factors, such as significant market volatility, very low or negative interest rates, periods of high redemption activity, or other factors could affect the Fund&#x2019;s ability to maintain a stable NAV.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="RetailProspectusMember_S000004463_MoneyMarketFundsandInterestRatesRiskMember"
      id="x_537e2678-8cc0-4400-9891-fdf85e8b2e44">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Money Market Funds and Interest Rates.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; In general, the prices of money market instruments are less sensitive to changes in interest rates than the prices of longer-term debt securities. However, money market fund income is based on short-term interest rates, which means the Fund&#x2019;s income may fluctuate significantly over short periods and may decline during periods of falling interest rates. In addition, interest rate changes could have unpredictable impacts on the overall market, which could negatively impact the Fund. For example, the Fund may be subject to loss if interest rates increase substantially and/or rapidly. Depending on the duration and severity, a period of low or negative interest rates could prevent the Fund from, among other things, providing a positive yield to its shareholders, paying expenses out of current income, and/or achieving its investment objective, including maintaining a stable NAV of $1.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004463_CreditRiskMember"
      id="x_4c720459-ef2e-41fe-9a3c-fe6cf08478ad">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Credit Risk&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; Credit risk refers to the chance that an issuer will default (fail to meet its credit obligations) or fail to make payments in a timely manner, which could result in a loss to the Fund. In addition, negative perceptions of an issuer&#x2019;s ability to make payments can cause the price of a security to decline. While all debt securities are subject to credit risk to some extent, those with &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:0.0pt;"&gt;higher credit quality ratings generally pose less credit risk than those with lower credit quality ratings.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004463_BondLiquidityRiskMember"
      id="x_60778aa2-5fbb-4420-a3be-c90b17de8b76">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Bond Liquidity Risk&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; If the Fund is unable to sell a security at an advantageous time or price, its returns may be reduced. There may be limited trading in the secondary market for certain debt securities, which could make them more difficult to value or sell.&lt;/span&gt;</oef:RiskTextBlock>
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      id="x_499c9413-d746-4d22-832a-a69a644bfd66">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Repurchase Agreements.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund invests in repurchase agreements, which are agreements under which the Fund acquires a security from a seller while simultaneously agreeing to resell the security to the seller at an agreed-upon price on a specific date. If the seller does not fulfill its obligation, the Fund could lose money, suffer delays, or incur costs arising from holding or selling the security.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004463_VariableFloatingRateSecuritiesRiskMember"
      id="ef102243-1d39-4943-8306-811b92d51e5f">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Variable and Floating Rate Securities.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund may invest in securities that pay variable or floating rates of interest. At any given time, the current interest rate of a variable or floating rate security may not accurately reflect current market interest rates, or may yield less than is appropriate to compensate the investor for the issuer&#x2019;s current credit quality. As a result, the value of the Fund&#x2019;s investments in such securities is subject to decline. In addition, an active market for variable and floating rate securities may not always exist at the time the Fund wishes to dispose of them.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004463_ActiveManagementRiskMember"
      id="e4fdd1df-2882-4a90-ac44-6b4a0798aa10">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Active Management.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund is actively managed. The advisor&#x2019;s security selection and/or strategy execution could cause the Fund to underperform relevant securities markets or other funds with a similar investment objective.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="RetailProspectusMember_S000004463_IndustryConcentrationRiskMember"
      id="x_72bf740c-a596-49b2-88c9-ab77408d5be2">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Industry Concentration&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;. The Fund concentrates its investments in the securities of issuers in the financial services industry. As a result, the Fund&#x2019;s performance depends to a greater extent on the overall condition of, and is more susceptible to events affecting, this industry.&lt;/span&gt;</oef:RiskTextBlock>
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      id="x_63861458-0be8-4b99-a3bc-6031141b9501">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt; Although the Fund seeks &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;to preserve the value of your investment at $1 per share, it cannot guarantee it will do so. &lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004463_RiskNotInsuredMember"
      id="x_98338805-be10-4dd7-96ed-01185a9ea0c7">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;An investment in the Fund is not a bank account &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. &lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004463_RiskMoneyMarketFundSponsorMayNotProvideSupportMember"
      id="e5155091-bda5-4599-9c13-f7c0263d2fd5">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;The Fund&#x2019;s sponsor is not &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;required to reimburse the Fund for losses, and you should not expect that the sponsor will provide financial support to the Fund at any time, including during periods of market stress.&lt;/span&gt;</oef:RiskTextBlock>
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      id="x_965adf78-2949-4574-9982-76b85478106b">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Annual Total Returns&lt;/span&gt;</oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="RetailProspectusMember_S000004463"
      id="x_9b923d1a-6913-4aaa-a0be-b45a4e395e62">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Effective September 29, 2020, the Fund changed its investment strategy and name, and changed its designation to a government money market fund. Performance for the periods prior to September 29, 2020, is based on the investment strategy utilized by the Fund prior to September 29, 2020, under the name Vanguard Prime Money Market Fund. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The following bar chart and table &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;show the Fund&#x2019;s historical performance and are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Fund compare with those of a relevant peer group average and one or more additional indexes with similar investment characteristics as the Fund.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; Returns &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;for the U.S. Government Money Market Funds Average are derived from data provided by Lipper, a Thomson Reuters Company. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Keep in mind that the Fund&#x2019;s &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;past performance does not indicate how the Fund will perform in the future.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Updated performance information is available on our website at &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;"&gt;vanguard.com/performance&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;.&lt;/span&gt;</oef:PerformanceNarrativeTextBlock>
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      id="d20ba031-d237-4228-8bcc-3f476cf1d88f">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The following bar chart and table &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;show the Fund&#x2019;s historical performance and are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Fund compare with those of a relevant peer group average and one or more additional indexes with similar investment characteristics as the Fund.&lt;/span&gt;</oef:PerformanceInformationIllustratesVariabilityOfReturns>
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      id="a11e7e82-006e-42a1-a6b4-e5b7f6fe9474">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Keep in mind that the Fund&#x2019;s &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;past performance does not indicate how the Fund will perform in the future.&lt;/span&gt;</oef:PerformancePastDoesNotIndicateFuture>
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      id="x_424d35d7-a630-4623-8ff8-d38e7e0813ee">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;"&gt;vanguard.com/performance&lt;/span&gt;</oef:PerformanceAvailabilityWebSiteAddress>
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      id="dd37ebc1-c646-464b-adc8-4781f55656a6">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;font-weight:bold;"&gt;Annual Total Returns &#x2014; Vanguard Cash Reserves Federal Money Market Fund Admiral Shares&lt;/span&gt;</oef:BarChartHeading>
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      id="x_87b13627-4d23-44bb-8d7d-d2ac578ee02d">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The highest and lowest returns for a calendar quarter during the periods shown in the bar chart and the year-to-date return as of the most recent calendar quarter were:&lt;/span&gt;</oef:BarChartClosingTextBlock>
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      id="x_515f503c-de34-4350-85b6-eac643766e6a">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;"&gt;Highest&lt;/span&gt;</oef:HighestQuarterlyReturnLabel>
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      decimals="4"
      id="x_5a4370c4-82ab-4c8a-a111-579de5e7ec06"
      unitRef="pure">0.0134</oef:BarChartHighestQuarterlyReturn>
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      contextRef="RetailProspectusMember_S000004463_C000012240"
      id="a5073e6b-049e-4730-bb94-1cc446fb9fe5">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
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      id="x_16e7acf3-65a3-4654-8614-90c318e5f4ab">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;"&gt;Lowest&lt;/span&gt;</oef:LowestQuarterlyReturnLabel>
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      decimals="4"
      id="bc4f7116-6c24-4121-a658-ebeff55926b7"
      unitRef="pure">0.0000</oef:BarChartLowestQuarterlyReturn>
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      contextRef="RetailProspectusMember_S000004463_C000012240"
      id="x_77948ddf-f927-42a4-996a-82a32bd1ca72">2021-06-30</oef:BarChartLowestQuarterlyReturnDate>
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      id="x_3a12320d-a56e-48f8-8473-6320d6a650e3">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;"&gt;Year-to-Date Return&lt;/span&gt;</oef:YearToDateReturnLabel>
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      contextRef="RetailProspectusMember_S000004463_C000012240"
      decimals="4"
      id="x_903cdc8d-624d-4678-ab42-6e27cc17b867"
      unitRef="pure">0.0321</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="RetailProspectusMember_S000004463_C000012240"
      id="x_63148e24-643a-4628-bcc6-8607b8e0b6c2">2025-09-30</oef:BarChartYearToDateReturnDate>
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      id="x_78f2def3-aae1-4e59-bd76-f33301283d82">&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;font-weight:bold;"&gt;Average Annual Total Returns for Periods Ended December 31, 2024&lt;/span&gt;</oef:PerformanceTableHeading>
    <oef:AvgAnnlRtrPct
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      decimals="4"
      id="x_9991c01d-bfe0-48a5-b9ec-2e793ebb8b65"
      unitRef="pure">0.0524</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_C000012240_01Jan2020_31Dec2024"
      decimals="4"
      id="x_4bd37894-9ea9-423a-804f-f7e4dc91eefa"
      unitRef="pure">0.0248</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_C000012240_01Jan2015_31Dec2024"
      decimals="4"
      id="x_85bcc8ed-f19b-4f36-82ab-fd4a09563649"
      unitRef="pure">0.0184</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_FTSE3MonthUSTreasuryBillIndexMember_01Jan2024_31Dec2024"
      decimals="4"
      id="x_33c9461f-5b89-4409-a14c-31cef9f3e799"
      unitRef="pure">0.0545</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_FTSE3MonthUSTreasuryBillIndexMember_01Jan2020_31Dec2024"
      decimals="4"
      id="x_956691c9-3e27-4a67-b239-8e2bb207fd03"
      unitRef="pure">0.0254</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_FTSE3MonthUSTreasuryBillIndexMember_01Jan2015_31Dec2024"
      decimals="4"
      id="x_62df53e8-bae8-4270-9401-847dc59f0b41"
      unitRef="pure">0.0179</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_USGovernmentMoneyMarketFundsAverageMember_01Jan2024_31Dec2024"
      decimals="4"
      id="e5f04908-065e-4be3-acb6-3c5a9f4e113a"
      unitRef="pure">0.0473</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_USGovernmentMoneyMarketFundsAverageMember_01Jan2020_31Dec2024"
      decimals="4"
      id="x_0471a08f-8dae-453c-bd2f-7a7d107ba837"
      unitRef="pure">0.0215</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_USGovernmentMoneyMarketFundsAverageMember_01Jan2015_31Dec2024"
      decimals="4"
      id="x_57d95e6f-4e9a-4640-af76-67af06869636"
      unitRef="pure">0.0139</oef:AvgAnnlRtrPct>
    <oef:RiskReturnHeading
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      id="x_89440367-a5b1-43f9-a80a-221d9c0a55d7">&lt;span style="color:#000000;font-family:Arial;font-size:13pt;font-weight:bold;"&gt;Vanguard Federal Money Market Fund&lt;/span&gt;</oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="RetailProspectusMember_S000004462"
      id="x_22bed86b-0c75-4187-bb2d-1445fb09e2ce">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Investment Objective&lt;/span&gt;</oef:ObjectiveHeading>
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      id="e6c279d2-08db-4592-9e43-dff7b73fa88e">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Vanguard Federal Money Market Fund (the &#x201c;Fund&#x201d;) seeks to provide current income while maintaining liquidity and a stable share price of $1.&lt;/span&gt;</oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
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      id="x_9e5125a0-ab57-43f4-8e0f-3e3781abbc56">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Fees and Expenses&lt;/span&gt;</oef:ExpenseHeading>
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      id="b933ee27-590e-428c-bcad-b32f6bf9442b">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The following tables describe the fees and expenses you may pay if you buy, hold, and sell shares of the Fund. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.&lt;/span&gt;</oef:ExpenseNarrativeTextBlock>
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      id="x_8c84aa9e-770f-459c-a3f0-d3e08a9512f6">&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;font-weight:bold;"&gt;Shareholder Fees&lt;/span&gt;
&lt;br/&gt;&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;"&gt;(Fees paid directly from your investment)&lt;/span&gt;</oef:ShareholderFeesCaption>
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      id="x_66833b26-d554-4595-ba2d-b75fad8750c5"
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      id="x_9c443d84-60b8-4d3c-a089-5779628e014d">&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;font-weight:bold;"&gt;Annual Fund Operating Expenses&lt;/span&gt;
&lt;br/&gt;&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;"&gt;(Expenses that you pay each year as a percentage of the value of your investment)&lt;/span&gt;</oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
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      id="x_6c9a15d3-7cd1-46be-a5a9-cdeac698446e"
      unitRef="pure">0.0010</oef:ManagementFeesOverAssets>
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      decimals="4"
      id="c7fa3575-ec91-4a97-9763-76d0d3f00d0d"
      unitRef="pure">0.0001</oef:OtherExpensesOverAssets>
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      decimals="4"
      id="ea82c75c-1dc7-49d0-bfd2-50a0014178c9"
      unitRef="pure">0.0011</oef:ExpensesOverAssets>
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      id="x_41f024b2-439f-4983-b079-abf7df962552">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Example&lt;/span&gt;</oef:ExpenseExampleHeading>
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      id="a1d0af0f-eeb4-4255-a4d9-5e0d01f5162b">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund&#x2019;s operating expenses remain the same.&lt;/span&gt;</oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
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      decimals="INF"
      id="x_49644a32-2f43-4e6e-b9a5-87f56778629e"
      unitRef="USD">11</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
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      decimals="INF"
      id="x_621881ed-ee21-4eda-94fe-c1ade38df25f"
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      decimals="INF"
      id="x_2219839f-a2f9-4115-b134-8ed17ac53843"
      unitRef="USD">62</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
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      decimals="INF"
      id="fbd4d1db-27f1-4b4d-b5d4-e3b1546a1cb0"
      unitRef="USD">141</oef:ExpenseExampleYear10>
    <oef:StrategyHeading
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      id="x_78936df9-facd-46f1-9261-f2d1d4e9e668">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Principal Investment Strategies&lt;/span&gt;</oef:StrategyHeading>
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      contextRef="RetailProspectusMember_S000004462"
      id="x_714ca435-da85-4473-a505-89306c88bb6e">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The Fund is actively managed, investing primarily in high-quality, short-term money market instruments. Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in securities issued by the U.S. government and its agencies and instrumentalities, which includes repurchase agreements that are collateralized solely by U.S. government securities or by cash.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;line-height:11.5pt;"&gt;The Fund has elected to operate as a government money market fund under Rule 2a-7 of the Investment Company Act of 1940, as amended. Government money market funds are required to invest at least 99.5% of their total assets in cash, U.S. government securities, and/or repurchase agreements that are collateralized solely by U.S. government securities or by cash. The Fund generally invests 100% of its assets in U.S. government securities (including repurchase agreements) and therefore satisfies the requirement for designation as a government money market fund. The Fund seeks to maintain a stable share price, or net asset value (NAV), of $1; maintains a dollar-weighted average maturity of 60 days or less and a dollar-weighted average life of 120 days or less; and invests in high-quality securities with effective maturities of 397 days or less. To be eligible for investment by the Fund, a security must be determined by methods approved by the board of trustees of Vanguard Money Market Reserves to present minimal credit risk. As a result, the Fund selects securities based in part on a consideration of maturity, portfolio diversification, portfolio liquidity, and credit quality. Some of the securities held by the Fund, while still considered high quality, are neither guaranteed by the U.S. Treasury nor supported by the full faith and credit of the U.S. government. Securities held by the Fund may pay fixed, variable, or floating rates of interest.&lt;/span&gt;</oef:StrategyNarrativeTextBlock>
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      id="x_99861178-1f50-4875-8b68-2fd9473a0111">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;As with any investment, an investment in the Fund could lose money over any time period.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;You could lose money by investing in the Fund.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_GeneralMarketRiskMember"
      id="x_96f090ba-35d4-4229-8f4a-9a458b05bc18">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;General Market Risk.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The markets in which the Fund invests can be affected by a variety of factors. These factors, which can be real or perceived, may include economic, market, political, and regulatory conditions and developments as well as local, regional, or global events such as wars, military conflicts, natural disasters, and public health issues. In addition, investor sentiment and expectations regarding these factors can also impact the markets. Different parts of the market, including different industries and sectors as well as different types of securities, may react differently to factors that affect the market. These factors can contribute to market uncertainty, market volatility, and fluctuations in the value of the Fund&#x2019;s investments, thereby resulting in potential losses to the Fund over short or long periods.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_InvestingInBondMarketsRiskMember"
      id="x_968cda1c-b97a-4b4d-a387-dd4b406d7878">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Investing in Bond Markets&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund invests in money market instruments, which are high quality, short-term debt securities. As a result, the Fund may &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:0.0pt;"&gt;be impacted by the general condition of the bond markets and by factors that affect bonds and bond issuers. For example, as a general rule, bond prices and interest rates move in opposite directions. When interest rates rise, bond prices tend to fall, and when interest rates fall, bond prices tend to go up. Bond income also is affected by changes in interest rates. Interest rates can rise or fall for a number of reasons, including, but not limited to, central bank monetary policy, inflationary or deflationary pressures, and changes in general market and economic conditions. Changing interest rates, including, but not limited to, rates that fall below zero, could have unpredictable effects on the overall market and may expose the bond markets in particular to heightened volatility and potential illiquidity. The degree to which the Fund is impacted by certain bond market risks may vary based on factors disclosed in its principal investment strategies, such as the types of bonds in which it invests and the overall credit quality, average maturity, and/or average duration of its bond holdings.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_StableNAVRiskMember"
      id="x_60955bf1-bcd6-4db4-b9be-4ff1e7ce331b">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Stable NAV&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;. There can be no assurance that the Fund will be successful in maintaining a stable NAV. A wide variety of factors, such as significant market volatility, very low or negative interest rates, periods of high redemption activity, or other factors could affect the Fund&#x2019;s ability to maintain a stable NAV.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_MoneyMarketFundsandInterestRatesRiskMember"
      id="a271e782-d8e2-4886-be9a-2aa3755c86ab">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Money Market Funds and Interest Rates.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; In general, the prices of money market instruments are less sensitive to changes in interest rates than the prices of longer-term debt securities. However, money market fund income is based on short-term interest rates, which means the Fund&#x2019;s income may fluctuate significantly over short periods and may decline during periods of falling interest rates. In addition, interest rate changes could have unpredictable impacts on the overall market, which could negatively impact the Fund. For example, the Fund may be subject to loss if interest rates increase substantially and/or rapidly. Depending on the duration and severity, a period of low or negative interest rates could prevent the Fund from, among other things, providing a positive yield to its shareholders, paying expenses out of current income, and/or achieving its investment objective, including maintaining a stable NAV of $1.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_CreditRiskMember"
      id="x_39494afa-0008-4245-80bf-0e831890cb68">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Credit Risk&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; Credit risk refers to the chance that an issuer will default (fail to meet its credit obligations) or fail to make payments in a timely manner, which could result in a loss to the Fund. In addition, negative perceptions of an issuer&#x2019;s ability to make payments can cause the price of a security to decline. While all debt securities are subject to credit risk to some extent, those with higher credit quality ratings generally pose less credit risk than those with lower credit quality ratings.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_BondLiquidityRiskMember"
      id="x_1604bffa-ee26-43df-98ac-c895ba0dc451">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Bond Liquidity Risk&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; If the Fund is unable to sell a security at an advantageous time or price, its returns may be reduced. There may be limited trading in the secondary market for certain debt securities, which could make them more difficult to value or sell.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_RepurchaseAgreementsRiskMember"
      id="d1383641-b0a3-4214-8095-9f8d7f4669f2">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Repurchase Agreements.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund invests in repurchase agreements, which are agreements under which the Fund acquires a security from a seller while simultaneously agreeing to resell the security to the seller at an agreed-upon price on a specific date. If the seller does not fulfill its obligation, the Fund could lose money, suffer delays, or incur costs arising from holding or selling the security.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_VariableFloatingRateSecuritiesRiskMember"
      id="x_2a1fc2f7-d169-4f8a-b22d-698ea3885858">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Variable and Floating Rate Securities.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund may invest in securities that pay variable or floating rates of interest. At any given time, the current interest rate of a variable or floating rate security may not accurately reflect current market interest rates, or may yield less than is appropriate to compensate the investor for the issuer&#x2019;s current credit quality. As a result, the value of the Fund&#x2019;s investments in such securities is subject to decline. In addition, an active market for variable and floating rate securities may not always exist at the time the Fund wishes to dispose of them.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_ActiveManagementRiskMember"
      id="aaef5a05-480b-417d-960c-e49928697101">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;margin-left:-8.6pt;"&gt;&#x2022;&#x2002;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;font-weight:bold;"&gt;Active Management.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; The Fund is actively managed. The advisor&#x2019;s security selection and/or strategy execution could cause the Fund to underperform relevant securities markets or other funds with a similar investment objective.&lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_RiskMoneyMarketFundMayNotPreserveDollarMember"
      id="x_8ed70147-75d6-45a6-8975-515a2ee4be68">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt; Although the Fund seeks &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;to preserve the value of your investment at $1 per share, it cannot guarantee it will do so. &lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_RiskNotInsuredMember"
      id="c31a2bd6-3fe4-43bf-8f20-dac3c6974a66">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;An investment in the Fund is not a bank account &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. &lt;/span&gt;</oef:RiskTextBlock>
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      contextRef="RetailProspectusMember_S000004462_RiskMoneyMarketFundSponsorMayNotProvideSupportMember"
      id="ccc2924e-bd12-46dd-8ce0-b6068013b038">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;The Fund&#x2019;s sponsor is not &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-weight:bold;"&gt;required to reimburse the Fund for losses, and you should not expect that the sponsor will provide financial support to the Fund at any time, including during periods of market stress.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="RetailProspectusMember_S000004462"
      id="f57557ec-28a0-4e66-8e42-7a63d8d1fbcb">&lt;span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;"&gt;Annual Total Returns&lt;/span&gt;</oef:BarChartAndPerformanceTableHeading>
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      contextRef="RetailProspectusMember_S000004462"
      id="x_4cbc490c-9243-4e41-8304-34a4c1d15f1e">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The following bar chart and table show the Fund&#x2019;s historical performance and are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Fund compare with those of a relevant peer group average and one or more additional indexes with similar investment characteristics as the Fund.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; Returns for the U.S. Government Money Market &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Funds Average are derived from data provided by Lipper, a Thomson Reuters Company. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Keep in mind that the Fund&#x2019;s past performance does not indicate &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;how the Fund will perform in the future.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt; Updated performance information is &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;available on our website at &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;"&gt;vanguard.com/performance&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;.&lt;/span&gt;</oef:PerformanceNarrativeTextBlock>
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      contextRef="RetailProspectusMember_S000004462"
      id="x_70156f9f-7e41-4477-ba7c-f78c6c95bcf4">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The following bar chart and table show the Fund&#x2019;s historical performance and are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Fund compare with those of a relevant peer group average and one or more additional indexes with similar investment characteristics as the Fund.&lt;/span&gt;</oef:PerformanceInformationIllustratesVariabilityOfReturns>
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      contextRef="RetailProspectusMember_S000004462"
      id="e1b74b54-07d6-4d35-a7e4-b39caa372a49">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;Keep in mind that the Fund&#x2019;s past performance does not indicate &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;how the Fund will perform in the future.&lt;/span&gt;</oef:PerformancePastDoesNotIndicateFuture>
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      contextRef="RetailProspectusMember_S000004462"
      id="x_31ecfea6-35da-4f53-8ea3-d95170f2c524">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;"&gt;vanguard.com/performance&lt;/span&gt;</oef:PerformanceAvailabilityWebSiteAddress>
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      contextRef="RetailProspectusMember_S000004462"
      id="cb5d00d4-55e2-45b0-8b3f-9707549d2527">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;font-weight:bold;"&gt;Annual Total Returns &#x2014; Vanguard Federal Money Market Fund Investor Shares&lt;/span&gt;</oef:BarChartHeading>
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      id="x_8acdc07d-0e64-4af8-b95a-dbd08087b132">&lt;span style="color:#000000;font-family:Arial;font-size:9.5pt;"&gt;The highest and lowest returns for a calendar quarter during the periods shown in the bar chart and the year-to-date return as of the most recent calendar quarter were:&lt;/span&gt;</oef:BarChartClosingTextBlock>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      id="x_4fdac3a8-b015-40d4-9d92-3c456c8cd7f0">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;"&gt;Highest&lt;/span&gt;</oef:HighestQuarterlyReturnLabel>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      decimals="4"
      id="f19b98d8-1c6c-4a5d-ba62-11189f7f6a43"
      unitRef="pure">0.0134</oef:BarChartHighestQuarterlyReturn>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      id="x_50767bf0-5616-4c57-b593-14455a274161">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
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      id="fe317f5e-a924-4853-a2a3-0dd0f5b9bf16">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;"&gt;Lowest&lt;/span&gt;</oef:LowestQuarterlyReturnLabel>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      decimals="4"
      id="x_9baeae7c-d65c-4ff6-91d8-21a80e15db6b"
      unitRef="pure">0.0000</oef:BarChartLowestQuarterlyReturn>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      id="x_71f34a77-2016-49f9-b07c-e1b3da66d09e">2015-03-31</oef:BarChartLowestQuarterlyReturnDate>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      id="x_5276ffd4-7e20-450d-b815-f93b5a8c946f">&lt;span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;"&gt;Year-to-Date Return&lt;/span&gt;</oef:YearToDateReturnLabel>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      decimals="4"
      id="x_5037db81-39b3-49f3-a1ea-74a94b1a6a5e"
      unitRef="pure">0.0320</oef:BarChartYearToDateReturn>
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      contextRef="RetailProspectusMember_S000004462_C000012238"
      id="x_53092026-ea99-4eed-bed4-f0e2d27fc35e">2025-09-30</oef:BarChartYearToDateReturnDate>
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      id="a2f460dc-e159-4596-9c53-22dfbf661980">&lt;span style="color:#000000;font-family:Arial;font-size:8.5pt;font-weight:bold;"&gt;Average Annual Total Returns for Periods Ended December 31, 2024&lt;/span&gt;</oef:PerformanceTableHeading>
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      unitRef="pure">0.0523</oef:AvgAnnlRtrPct>
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      contextRef="RetailProspectusMember_C000012238_01Jan2020_31Dec2024"
      decimals="4"
      id="x_89b0342c-f41b-4fe7-9e45-b85a7cc61175"
      unitRef="pure">0.0244</oef:AvgAnnlRtrPct>
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      contextRef="RetailProspectusMember_C000012238_01Jan2015_31Dec2024"
      decimals="4"
      id="x_66402fc3-ed90-4dcd-af2e-574af28a6806"
      unitRef="pure">0.0172</oef:AvgAnnlRtrPct>
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      contextRef="RetailProspectusMember_FTSE3MonthUSTreasuryBillIndexMember_01Jan2024_31Dec2024"
      decimals="4"
      id="f6cec552-493f-4e86-9b88-aa65a0b7fd61"
      unitRef="pure">0.0545</oef:AvgAnnlRtrPct>
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      contextRef="RetailProspectusMember_FTSE3MonthUSTreasuryBillIndexMember_01Jan2020_31Dec2024"
      decimals="4"
      id="x_3dfd82e8-8d1a-413f-908d-04e05a5da166"
      unitRef="pure">0.0254</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_FTSE3MonthUSTreasuryBillIndexMember_01Jan2015_31Dec2024"
      decimals="4"
      id="x_0162c922-da9b-48cc-ab06-43ca8bc0330a"
      unitRef="pure">0.0179</oef:AvgAnnlRtrPct>
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      contextRef="RetailProspectusMember_USGovernmentMoneyMarketFundsAverageMember_01Jan2024_31Dec2024"
      decimals="4"
      id="e1394978-ca60-4125-b4ac-495d48f1e709"
      unitRef="pure">0.0473</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_USGovernmentMoneyMarketFundsAverageMember_01Jan2020_31Dec2024"
      decimals="4"
      id="d3c59203-df17-45fb-b80e-0e4c75f173df"
      unitRef="pure">0.0215</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="RetailProspectusMember_USGovernmentMoneyMarketFundsAverageMember_01Jan2015_31Dec2024"
      decimals="4"
      id="e4881ade-48d6-4fb3-b5bc-14e4ab7307c8"
      unitRef="pure">0.0139</oef:AvgAnnlRtrPct>
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