Vanguard Inflation-Protected Securities Fund Investment Risks - Institutional Prospectus [Member] - Vanguard Inflation-Protected Securities Fund	Dec. 31, 2025
General Market Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• General Market Risk. 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’s investments, thereby resulting in potential losses to the Fund over short or long periods.
Investing in Bond Markets Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Investing in Bond Markets. 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.
Interest Rate Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Interest Rate Risk. During periods of rising interest rates, bond prices overall may decline, which could result in a decline in the Fund’s value. The prices of longer-term bonds are more sensitive to changes in interest rates than the prices of shorter-term bonds.
Income Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Income Risk. During periods of falling interest rates, the Fund’s income may decline. The income paid by shorter-term bonds is subject to a higher degree of fluctuation than the income paid by longer-term bonds.
Credit Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Credit Risk. 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’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.
Bond Liquidity Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Bond Liquidity Risk. 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.
Inflation Indexed Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Inflation-Indexed Securities. Because they are adjusted for inflation, TIPS and other inflation-indexed securities typically have lower yields than conventional bonds. As a result of its investment in such securities, the Fund’s income distributions are likely to fluctuate considerably more than the income distributions of a conventional bond fund. In fact, under certain conditions, the Fund may not have income to distribute at all. Although the prices of inflation-indexed securities are not meaningfully affected by changes in “nominal” (stated) interest rates, their prices may decline when “real” (adjusted for inflation) interest rates rise, and vice versa. The prices of inflation-indexed securities also are subject to decline if prices throughout the U.S. economy decline over time (a period of deflation), which could result in a loss to the Fund and/or cause the Fund’s performance to lag that of conventional bond funds.
Active Management Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Active Management. The Fund is actively managed. The advisor’s security selection and/or strategy execution could cause the Fund to underperform relevant securities markets or other funds with a similar investment objective.
Derivatives Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	• Investing in Derivatives. Investing in derivatives may present risks different from, and/or greater than, those associated with investing directly in stocks, bonds, or other types of investments. Derivatives could expose the Fund to increased volatility and/or significant loss. Certain derivatives have an inherent leverage component, providing the Fund exposure to a sizable position in an underlying asset with a relatively small upfront investment at the time the Fund enters into the derivatives position. For these derivatives, an adverse change in the value or price of the underlying asset could result in a loss substantially greater than the amount invested in the derivative itself. Some derivatives require the Fund to enter into a contract with a counterparty. If the counterparty is unable or unwilling to fulfill its contractual obligation, the Fund may experience a loss. A liquid market may not always exist for the Fund’s derivatives positions. The Fund may be unable to sell or otherwise exit its derivatives position at desired times or prices, which could also result in a loss to the Fund. Some derivatives, particularly OTC derivatives, can be complex and often are valued subjectively. Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them. Improper valuations can result in increased cash payment requirements to counterparties or a loss of value to the Fund. Derivatives may not perform as intended, which may result in losses to the Fund. For example, derivatives used for hedging or as a substitute for a portfolio instrument may not provide the expected benefits, particularly during adverse market conditions. The use of derivatives is also subject to legal risk, which includes the risk of loss resulting from insufficient or unenforceable contractual documentation, insufficient capacity or authority of the Fund’s counterparty, and operational risk, which includes documentation or settlement issues, system failures, inadequate controls, and human error.
Risk Lose Money [Member]
Prospectus [Line Items]
Risk [Text Block]	As with any investment, an investment in the Fund could lose money over any time period.
Risk Not Insured Depository Institution [Member]
Prospectus [Line Items]
Risk [Text Block]	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Vanguard Inflation-Protected Securities Fund Investment Risks - Institutional Prospectus [Member] - Vanguard Inflation-Protected Securities Fund

Dec. 31, 2025

• General Market Risk. 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’s investments, thereby resulting in potential losses to the Fund over short or long periods.

Prospectus [Line Items]

Risk [Text Block]

• Investing in Bond Markets. 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.

Interest Rate Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

• Interest Rate Risk. During periods of rising interest rates, bond prices overall may decline, which could result in a decline in the Fund’s value. The prices of longer-term bonds are more sensitive to changes in interest rates than the prices of shorter-term bonds.

Income Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

• Income Risk. During periods of falling interest rates, the Fund’s income may decline. The income paid by shorter-term bonds is subject to a higher degree of fluctuation than the income paid by longer-term bonds.

Credit Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

• Credit Risk. 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’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.

Bond Liquidity Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

• Bond Liquidity Risk. 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.

Inflation Indexed Securities Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

• Inflation-Indexed Securities. Because they are adjusted for inflation, TIPS and other inflation-indexed securities typically have lower yields than conventional bonds. As a result of its investment in such securities, the Fund’s income distributions are likely to fluctuate considerably more than the income distributions of a conventional bond fund. In fact, under certain conditions, the Fund may not have income to distribute at all. Although the prices of inflation-indexed securities are not meaningfully affected by changes in “nominal” (stated) interest rates, their prices may decline when “real” (adjusted for inflation) interest rates rise, and vice versa. The prices of inflation-indexed securities also are subject to decline if prices throughout the U.S. economy decline over time (a period of deflation), which could result in a loss to the Fund and/or cause the Fund’s performance to lag that of conventional bond funds.

Active Management Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

• Active Management. The Fund is actively managed. The advisor’s security selection and/or strategy execution could cause the Fund to underperform relevant securities markets or other funds with a similar investment objective.

Derivatives Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

• Investing in Derivatives. Investing in derivatives may present risks different from, and/or greater than, those associated with investing directly in stocks, bonds, or other types of investments. Derivatives could expose the Fund to increased volatility and/or significant loss. Certain derivatives have an inherent leverage component, providing the Fund exposure to a sizable position in an underlying asset with a relatively small upfront investment at the time the Fund enters into the derivatives position. For these derivatives, an adverse change in the value or price of the underlying asset could result in a loss substantially greater than the amount invested in the derivative itself. Some derivatives require the Fund to enter into a contract with a counterparty. If the counterparty is unable or unwilling to fulfill its contractual obligation, the Fund may experience a loss. A liquid market may not always exist for the Fund’s derivatives positions. The Fund may be unable to sell or otherwise exit its derivatives position at desired times or prices, which could also result in a loss to the Fund. Some derivatives, particularly OTC derivatives, can be complex and often are valued subjectively. Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them. Improper valuations can result in increased cash payment requirements to counterparties or a loss of value to the Fund.
Derivatives may not perform as intended, which may result in losses to the Fund. For example, derivatives used for hedging or as a substitute for a portfolio instrument may not provide the expected benefits, particularly during adverse market conditions. The use of derivatives is also subject to legal risk, which includes the risk of loss resulting from insufficient or unenforceable contractual documentation, insufficient capacity or authority of the Fund’s counterparty, and operational risk, which includes documentation or settlement issues, system failures, inadequate controls, and human error.

Risk Lose Money [Member]

Prospectus [Line Items]

Risk [Text Block]

As with any investment, an investment in the Fund could lose money over any time period.

Risk Not Insured Depository Institution [Member]

Prospectus [Line Items]

Risk [Text Block]

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.