Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	VANGUARD MALVERN FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 25, 2019
Retail | Vanguard Short-Term Inflation-Protected Securities Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Summary
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks to track the performance of a benchmark index that measures the investment return of inflation-protected public obligations of the U.S. Treasury with remaining maturities of less than 5 years.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses you may pay if you buy and hold Investor Shares or Admiral Shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees<br/><br/> (Fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses<br/><br/> (Expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in more taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the previous expense examples, reduce the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 25% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	25.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Examples
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following examples are intended to help you compare the cost of investing in the Fund’s Investor Shares or Admiral Shares with the cost of investing in other mutual funds. They illustrate the hypothetical expenses that you would incur over various periods if you were to invest $10,000 in the Fund’s shares. These examples assume that the shares provide a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you were to redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund employs an indexing investment approach designed to track the performance of the Bloomberg Barclays U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Year Index. The Index is a market-capitalization-weighted index that includes all inflation-protected public obligations issued by the U.S. Treasury with remaining maturities of less than 5 years. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the securities that make up the Index, holding each security in approximately the same proportion as its weighting in the Index. The Fund maintains a dollar-weighted average maturity consistent with that of the target index, which generally does not exceed 3 years.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The Fund is designed for investors with a low tolerance for risk, but you could still lose money by investing in it. The Fund is subject to the following risks, which could affect the Fund’s performance: • Income fluctuations. The Fund’s quarterly income distributions are likely to fluctuate considerably more than the income distributions of a typical bond fund. In fact, under certain conditions, the Fund may not have any income to distribute. Income fluctuations associated with changes in interest rates are expected to be low; however, income fluctuations associated with changes in inflation are expected to be high. Overall, investors can expect income fluctuations to be high for the Fund. • Real interest rate risk, which is the chance that the value of a bond will fluctuate because of a change in the level of real, or after inflation, interest rates. Although inflation-indexed bonds seek to provide inflation protection, their prices may decline when real interest rates rise and vice versa. Because the Fund’s dollar-weighted average maturity is expected to be 5 years or less, real interest rate risk is expected to be low for the Fund. 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	The Fund is designed for investors with a low tolerance for risk, but you could still lose money by investing in it.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	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.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Annual Total Returns
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund‘s Investor Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the share classes presented compare with those of the Fund‘s target index, which has investment characteristics similar to those of the Fund. Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance or by calling Vanguard toll-free at 800-662-7447.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund‘s Investor Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the share classes presented compare with those of the Fund‘s target index, which has investment characteristics similar to those of the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-662-7447
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	vanguard.com/performance
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns — Vanguard Short-Term Inflation-Protected Securities Index Fund Investor Shares
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the periods shown in the bar chart, the highest return for a calendar quarter was 1.78% (quarter ended March 31, 2016), and the lowest return for a quarter was –2.42% (quarter ended June 30, 2013).
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns for Periods Ended December 31, 2018
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	After-tax returns are not relevant for a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	Please note that after-tax returns are shown only for the Investor Shares and may differ for each share class.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Actual after-tax returns depend on your tax situation and may differ from those shown in the preceding table. When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations. Please note that after-tax returns are shown only for the Investor Shares and may differ for each share class. After-tax returns are not relevant for a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.
Retail | Vanguard Short-Term Inflation-Protected Securities Index Fund | Investor Shares
Risk/Return:	rr_RiskReturnAbstract
Purchase Fee	rr_MaximumCumulativeSalesChargeOverOther	none
Sales Charge (Load) Imposed on Purchases	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Sales Charge (Load) Imposed on Reinvested Dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee	rr_RedemptionFeeOverRedemption	none
Account Service Fee (for certain fund account balances below $10,000)	rr_MaximumAccountFee	$ 20	[1]
Management Fees	rr_ManagementFeesOverAssets	0.12%
12b-1 Distribution Fee	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.02%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.14%
1 Year	rr_ExpenseExampleYear01	$ 14
3 Years	rr_ExpenseExampleYear03	45
5 Years	rr_ExpenseExampleYear05	79
10 Years	rr_ExpenseExampleYear10	179
1 Year	rr_ExpenseExampleNoRedemptionYear01	14
3 Years	rr_ExpenseExampleNoRedemptionYear03	45
5 Years	rr_ExpenseExampleNoRedemptionYear05	79
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 179
2013	rr_AnnualReturn2013	(1.62%)
2014	rr_AnnualReturn2014	(1.29%)
2015	rr_AnnualReturn2015	(0.21%)
2016	rr_AnnualReturn2016	2.59%
2017	rr_AnnualReturn2017	0.72%
2018	rr_AnnualReturn2018	0.49%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2016
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	1.78%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2013
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.42%)
1 Year	rr_AverageAnnualReturnYear01	0.49%
5 Years	rr_AverageAnnualReturnYear05	0.45%
Since Inception	rr_AverageAnnualReturnSinceInception	0.17%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 16, 2012
Retail | Vanguard Short-Term Inflation-Protected Securities Index Fund | Admiral Shares
Risk/Return:	rr_RiskReturnAbstract
Purchase Fee	rr_MaximumCumulativeSalesChargeOverOther	none
Sales Charge (Load) Imposed on Purchases	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Sales Charge (Load) Imposed on Reinvested Dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee	rr_RedemptionFeeOverRedemption	none
Account Service Fee (for certain fund account balances below $10,000)	rr_MaximumAccountFee	$ 20	[1]
Management Fees	rr_ManagementFeesOverAssets	0.05%
12b-1 Distribution Fee	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.06%
1 Year	rr_ExpenseExampleYear01	$ 6
3 Years	rr_ExpenseExampleYear03	19
5 Years	rr_ExpenseExampleYear05	34
10 Years	rr_ExpenseExampleYear10	77
1 Year	rr_ExpenseExampleNoRedemptionYear01	6
3 Years	rr_ExpenseExampleNoRedemptionYear03	19
5 Years	rr_ExpenseExampleNoRedemptionYear05	34
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 77
1 Year	rr_AverageAnnualReturnYear01	0.53%
5 Years	rr_AverageAnnualReturnYear05	0.54%
Since Inception	rr_AverageAnnualReturnSinceInception	0.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 16, 2012
Retail | Vanguard Short-Term Inflation-Protected Securities Index Fund | Return After Taxes on Distributions | Investor Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.47%)
5 Years	rr_AverageAnnualReturnYear05	0.02%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.18%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 16, 2012
Retail | Vanguard Short-Term Inflation-Protected Securities Index Fund | Return After Taxes on Distributions and Sale of Fund Shares | Investor Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.29%
5 Years	rr_AverageAnnualReturnYear05	0.16%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.02%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 16, 2012
Retail | Vanguard Short-Term Inflation-Protected Securities Index Fund | Bloomberg Barclays U.S. TIPS 0-5 Year Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.59%
5 Years	rr_AverageAnnualReturnYear05	0.62%
Since Inception	rr_AverageAnnualReturnSinceInception	0.27%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 16, 2012

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