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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Apr. 30, 2014
Registrant Name dei_EntityRegistrantName Vanguard Explorer Fund
Central Index Key dei_EntityCentralIndexKey 0000034066
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Aug. 15, 2014
Document Effective Date dei_DocumentEffectiveDate Aug. 15, 2014
Vanguard Explorer Fund | Participant
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Aug. 15, 2014
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital appreciation.
Expenses Heading rr_ExpenseHeading Fees and Expenses
Fees and Expenses of the Fund rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy and hold Investor Shares of the Fund.
Shareholder Fees Caption rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption rr_OperatingExpensesCaption Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover Heading rr_PortfolioTurnoverHeading

Portfolio Turnover
Portfolio Turnover 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 example, reduce the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 65% of the average value of its portfolio.
PortfolioTurnover, Rate rr_PortfolioTurnoverRate 65.00%
EXAMPLE rr_ExpenseExampleHeading

Example
Expense Example, Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

The following example is intended to help you compare the cost of investing in the Fund's Investor Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invest $10,000 in the Fund's shares. This example assumes that the Shares provide a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund invests mainly in the stocks of small companies. These companies tend to be unseasoned but are considered by the Fund's advisors to have superior growth potential. Also, these companies often provide little or no dividend income. The Fund uses multiple investment advisors.
Risk Narrative rr_RiskNarrativeTextBlock

An investment in the Fund could lose money over short or even long periods. You should expect the Fund's share price and total return to fluctuate within a wide range, like the fluctuations of the overall stock market. The Fund is subject to the following risks, which could affect the Fund's performance:

Stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices.

Investment style risk, which is the chance that returns from small-capitalization growth stocks will trail returns from the overall stock market. Historically, small-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently.

Manager risk, which is the chance that poor security selection will cause the Fund to underperform relevant benchmarks or other funds with a similar investment objective. Significant investment in the information technology sector subjects the Fund to proportionately higher exposure to the risks of this sector.

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.
May Lose Money rr_RiskLoseMoney

An investment in the Fund could lose money over short or even long periods.

Not Insured Depository Institution 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 rr_BarChartAndPerformanceTableHeading Annual Total Returns
Performance Information Illustrates Variability of Returns rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table are intended to help you understand the risks of investing in the Fund.
Performance Availability Phone rr_PerformanceAvailabilityPhone

800-662-7447
Performance Availability Website Address rr_PerformanceAvailabilityWebSiteAddress

vanguard.com/performance

Past Performance Does Not Indiciate Future Returns rr_PerformancePastDoesNotIndicateFuture

Keep in mind that the Fund's past performance does not indicate how the Fund will perform in the future.
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Explorer Fund Investor Shares
Bar Chart Narrative rr_BarChartNarrativeTextBlock

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 Investor Shares compare with those of a relevant market index, which has investment characteristics similar to those of the Fund. Keep in mind that the Fund's past performance 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.
Bar Chart Footnotes rr_BarChartFootnotesTextBlock

1 The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2014 was 2.32%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 19.79% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -26.16% (quarter ended December 31, 2008 ).
Year to Date Return Label rr_YearToDateReturnLabel The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2014
Highest Quarterly Return Label rr_HighestQuarterlyReturnLabel (quarter ended June 30, 2009 )
Lowest Quarterly Return Label rr_LowestQuarterlyReturnLabel (quarter ended December 31, 2008 )
Bar Chart and Performance Table: rr_PerformanceTableHeading Average Annual Total Returns for Periods Ended December 31, 2013
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees or expenses)
Vanguard Explorer Fund | Participant:
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Aug. 15, 2014
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital appreciation.
Expenses Heading rr_ExpenseHeading Fees and Expenses
Fees and Expenses of the Fund rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy and hold Admiral Shares of the Fund.
Shareholder Fees Caption rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption rr_OperatingExpensesCaption Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover Heading rr_PortfolioTurnoverHeading

Portfolio Turnover
Portfolio Turnover 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 example, reduce the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 65% of the average value of its portfolio.
PortfolioTurnover, Rate rr_PortfolioTurnoverRate 65.00%
EXAMPLE rr_ExpenseExampleHeading

Example
Expense Example, Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

The following example is intended to help you compare the cost of investing in the Fund's Admiral Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invest $10,000 in the Fund's shares. This example assumes that the Shares provide a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund invests mainly in the stocks of small companies. These companies tend to be unseasoned but are considered by the Fund's advisors to have superior growth potential. Also, these companies often provide little or no dividend income. The Fund uses multiple investment advisors.
Risk Narrative rr_RiskNarrativeTextBlock

An investment in the Fund could lose money over short or even long periods. You should expect the Fund's share price and total return to fluctuate within a wide range, like the fluctuations of the overall stock market. The Fund is subject to the following risks, which could affect the Fund's performance:

Stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices.

Investment style risk, which is the chance that returns from small-capitalization growth stocks will trail returns from the overall stock market. Historically, small-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently.

Manager risk, which is the chance that poor security selection will cause the Fund to underperform relevant benchmarks or other funds with a similar investment objective. Significant investment in the information technology sector subjects the Fund to proportionately higher exposure to the risks of this sector.

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.
May Lose Money rr_RiskLoseMoney

An investment in the Fund could lose money over short or even long periods.

Not Insured Depository Institution 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 rr_BarChartAndPerformanceTableHeading Annual Total Returns
Performance Information Illustrates Variability of Returns rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table are intended to help you understand the risks of investing in the Fund.
Performance Availability Phone rr_PerformanceAvailabilityPhone

800-662-7447
Performance Availability Website Address rr_PerformanceAvailabilityWebSiteAddress

vanguard.com/performance

Past Performance Does Not Indiciate Future Returns rr_PerformancePastDoesNotIndicateFuture

Keep in mind that the Fund's past performance does not indicate how the Fund will perform in the future.
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Explorer Fund Admiral Shares
Bar Chart Narrative rr_BarChartNarrativeTextBlock

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 Admiral Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Admiral Shares compare with those of a relevant market index, which has investment characteristics similar to those of the Fund. Keep in mind that the Fund's past performance 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.
Bar Chart Footnotes rr_BarChartFootnotesTextBlock

1 The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2014 was 2.40%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 19.87% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -26.11% (quarter ended December 31, 2008 ).
Year to Date Return Label rr_YearToDateReturnLabel The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2014
Highest Quarterly Return Label rr_HighestQuarterlyReturnLabel (quarter ended June 30, 2009 )
Lowest Quarterly Return Label rr_LowestQuarterlyReturnLabel (quarter ended December 31, 2008 )
Bar Chart and Performance Table: rr_PerformanceTableHeading Average Annual Total Returns for Periods Ended December 31, 2013
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees or expenses)
Vanguard Explorer Fund | Retail
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Aug. 15, 2014
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital appreciation.
Expenses Heading rr_ExpenseHeading Fees and Expenses
Fees and Expenses of the Fund 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 rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption rr_OperatingExpensesCaption Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover Heading rr_PortfolioTurnoverHeading

Portfolio Turnover
Portfolio Turnover 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 65% of the average value of its portfolio.
PortfolioTurnover, Rate rr_PortfolioTurnoverRate 65.00%
EXAMPLE 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 invest $10,000 in the Fund's shares. These examples assume that the Shares provide a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund invests mainly in the stocks of small companies. These companies tend to be unseasoned but are considered by the Fund's advisors to have superior growth potential. Also, these companies often provide little or no dividend income. The Fund uses multiple investment advisors.
Risk Narrative rr_RiskNarrativeTextBlock

An investment in the Fund could lose money over short or even long periods. You should expect the Fund's share price and total return to fluctuate within a wide range, like the fluctuations of the overall stock market. The Fund is subject to the following risks, which could affect the Fund's performance:

Stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices.

Investment style risk, which is the chance that returns from small-capitalization growth stocks will trail returns from the overall stock market. Historically, small-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently.

Manager risk, which is the chance that poor security selection will cause the Fund to underperform relevant benchmarks or other funds with a similar investment objective. Significant investment in the information technology sector subjects the Fund to proportionately higher exposure to the risks of this sector.

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.
May Lose Money rr_RiskLoseMoney

An investment in the Fund could lose money over short or even long periods.

Not Insured Depository Institution 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 rr_BarChartAndPerformanceTableHeading Annual Total Returns
Performance Information Illustrates Variability of Returns rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table are intended to help you understand the risks of investing in the Fund.
Performance Availability Phone rr_PerformanceAvailabilityPhone

800-662-7447
Performance Availability Website Address rr_PerformanceAvailabilityWebSiteAddress

vanguard.com/performance

Past Performance Does Not Indiciate Future Returns 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 rr_BarChartHeading Annual Total Returns - Vanguard Explorer Fund Investor Shares
Bar Chart Narrative rr_BarChartNarrativeTextBlock

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 a relevant market 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.
Bar Chart Footnotes rr_BarChartFootnotesTextBlock

1 The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2014 was 2.32%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 19.79% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -26.16% (quarter ended December 31, 2008 ).
Year to Date Return Label rr_YearToDateReturnLabel The year-to-date return as of the most recent calendar quarter, which ended on June 30, 2014
Highest Quarterly Return Label rr_HighestQuarterlyReturnLabel (quarter ended June 30, 2009 )
Lowest Quarterly Return Label rr_LowestQuarterlyReturnLabel (quarter ended December 31, 2008 )
Bar Chart and Performance Table: rr_PerformanceTableHeading Average Annual Total Returns for Periods Ended December 31, 2013
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
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.
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.

One Class of After-Tax Shown rr_PerformanceTableOneClassOfAfterTaxShown

Please note that after-tax returns are shown only for the Investor Shares and may differ for each share class.

Performance Table Explains why after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher

Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares will 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 Closing rr_PerformanceTableClosingTextBlock

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.
Vanguard Explorer Fund | Vanguard Explorer Fund - Investor Shares
  
Risk/Return: rr_RiskReturnAbstract  
Sales charge (load) imposed on purchases rr_MaximumCumulativeSalesChargeOverOfferingPrice none
Purchase Fee rr_MaximumCumulativeSalesChargeOverOther 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
Management Fees rr_ManagementFeesOverAssets 0.49%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.52% [1]
1 YEAR rr_ExpenseExampleNoRedemptionYear01 53
3 YEAR rr_ExpenseExampleNoRedemptionYear03 167
5 YEAR rr_ExpenseExampleNoRedemptionYear05 291
10 YEAR rr_ExpenseExampleNoRedemptionYear10 653
Annual Return Inception Date rr_AnnualReturnInceptionDate Dec. 11, 1967
2004 rr_AnnualReturn2004 13.75%
2005 rr_AnnualReturn2005 9.28%
2006 rr_AnnualReturn2006 9.70%
2007 rr_AnnualReturn2007 5.06%
2008 rr_AnnualReturn2008 (40.40%)
2009 rr_AnnualReturn2009 36.21%
2010 rr_AnnualReturn2010 27.43%
2011 rr_AnnualReturn2011 (1.89%)
2012 rr_AnnualReturn2012 14.89%
2013 rr_AnnualReturn2013 44.36%
Date rr_BarChartYearToDateReturnDate Jun. 30, 2014
Year to Date Return rr_BarChartYearToDateReturn 2.32%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.79%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (26.16%)
One Year rr_AverageAnnualReturnYear01 44.36%
Five Years rr_AverageAnnualReturnYear05 23.08%
Ten Years rr_AverageAnnualReturnYear10 9.20%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 11, 1967
Vanguard Explorer Fund | Vanguard Explorer Fund - Admiral Shares
  
Risk/Return: rr_RiskReturnAbstract  
Sales charge (load) imposed on purchases rr_MaximumCumulativeSalesChargeOverOfferingPrice none
Purchase Fee rr_MaximumCumulativeSalesChargeOverOther 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
Management Fees rr_ManagementFeesOverAssets 0.33%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.02%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.35% [1]
1 YEAR rr_ExpenseExampleNoRedemptionYear01 36
3 YEAR rr_ExpenseExampleNoRedemptionYear03 113
5 YEAR rr_ExpenseExampleNoRedemptionYear05 197
10 YEAR rr_ExpenseExampleNoRedemptionYear10 443
Annual Return Inception Date rr_AnnualReturnInceptionDate Nov. 12, 2001
2004 rr_AnnualReturn2004 13.92%
2005 rr_AnnualReturn2005 9.46%
2006 rr_AnnualReturn2006 9.88%
2007 rr_AnnualReturn2007 5.26%
2008 rr_AnnualReturn2008 (40.29%)
2009 rr_AnnualReturn2009 36.45%
2010 rr_AnnualReturn2010 27.64%
2011 rr_AnnualReturn2011 (1.72%)
2012 rr_AnnualReturn2012 15.07%
2013 rr_AnnualReturn2013 44.59%
Date rr_BarChartYearToDateReturnDate Jun. 30, 2014
Year to Date Return rr_BarChartYearToDateReturn 2.40%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.87%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (26.11%)
One Year rr_AverageAnnualReturnYear01 44.59%
Five Years rr_AverageAnnualReturnYear05 23.28%
Ten Years rr_AverageAnnualReturnYear10 9.39%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 12, 2001
Russell 2500 Growth Index | Vanguard Explorer Fund | Vanguard Explorer Fund - Investor Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 40.65%
Five Years rr_AverageAnnualReturnYear05 24.03%
Ten Years rr_AverageAnnualReturnYear10 10.11%
Russell 2500 Growth Index | Vanguard Explorer Fund | Vanguard Explorer Fund - Investor Shares | Participant
  
Risk/Return: rr_RiskReturnAbstract  
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees or expenses)
Russell 2500 Growth Index | Vanguard Explorer Fund | Vanguard Explorer Fund - Investor Shares | Retail
  
Risk/Return: rr_RiskReturnAbstract  
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
Russell 2500 Growth Index | Vanguard Explorer Fund | Vanguard Explorer Fund - Admiral Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 40.65%
Five Years rr_AverageAnnualReturnYear05 24.03%
Ten Years rr_AverageAnnualReturnYear10 10.11%
Russell 2500 Growth Index | Vanguard Explorer Fund | Vanguard Explorer Fund - Admiral Shares | Participant:
  
Risk/Return: rr_RiskReturnAbstract  
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees or expenses)
[1] The expense information shown in the table has been restated to reflect estimated amounts for the current fiscal year.