Prospectus: Document Type Period End Date Document Period End Date Registrant Name CIK Entity Central Index Key Amendment Flag Document Created Date Document Creation Date Document Effective Date Prospectus Date Legal Entity Identifier Entity Inv Company Type Amendment Description Trading Symbol Net Expenses (as a percentage of Assets) Net Expenses Expenses (as a percentage of Assets) Total Annual Fund Operating Expenses Total Annual Fund Operating Expenses Management Fees (as a percentage of Assets) Management Fees Distribution and Service (12b-1) Fees 12b-1 Distribution Fee Distribution or Similar (Non 12b-1) Fees Other Expenses (as a percentage of Assets): Other Expenses Other Expenses Component1 Other Expenses Component2 Other Expenses Component3 Other Expenses Acquired Fund Fees and Expenses Acquired Fund Fees and Expenses Fee Waiver or Reimbursement Fee Waiver or Reimbursement Performance Measure [Axis] Share Class [Axis] Document [Axis] Prospectus Investor [Member] Investor Investor [Member] Coregistrant [Axis] Coregistrant [Domain] Series [Axis] Series S000028087 [Member] Vanguard Explorer Value Fund Vanguard Explorer Value Fund Member Before Taxes After Taxes on Distributions After Taxes on Distributions and Sales Return After Taxeson Distributions [Member] Return After Taxeson Distributions Member Return After Taxes on Distributions Return After Taxeson Distributionsand Saleof Fund Shares [Member] Return After Taxeson Distributionsand Saleof Fund Shares Member Return After Taxes on Distributions and Sale of Fund Shares Russell Two Five Hundred Value Index [Member] Russell Two Five Hundred Value Index Member Russell 2500 Value Index (reflects no deduction for fees, expenses, or taxes) Dow Jones U S Total Stock Market Float Adjusted Index [Member] Dow Jones U S Total Stock Market Float Adjusted Index Member Dow Jones U.S. Total Stock Market Float Adjusted Index (reflects no deduction for fees, expenses, or taxes) Share Classes C000085513 [Member] Investor Shares Investor Shares Risk [Axis] All Risks [Member] Risk Nondiversified Status [Member] Risk Lose Money [Member] Risk Money Market Fund Price Fluctuates [Member] Risk Money Market Fund May Impose Fees or Suspend Sales [Member] Risk Money Market Fund May Not Preserve Dollar [Member] Risk Money Market Fund Sponsor May Not Provide Support [Member] Risk Not Insured Depository Institution [Member] Risk Not Insured [Member] Risk/Return [Heading] Objective [Heading] Objective, Primary [Text Block] Expense [Heading] Expense Narrative [Text Block] Shareholder Fees Caption [Text] Purchase Fee Maximum Cumulative Sales Charge (as a percentage) Sales Charge (Load) Imposed on Purchases Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) Sales Charge (Load) Imposed on Reinvested Dividends Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) Redemption Fee Redemption Fee (as a percentage of Amount Redeemed) Account Service Fee Per Year (for certain fund account balances below $5,000,000) Maximum Account Fee Operating Expenses Caption [Text] Portfolio Turnover [Heading] Portfolio Turnover [Text Block] Portfolio Turnover, Rate Expense Example [Heading] Expense Example Narrative [Text Block] 1 Year Expense Example, with Redemption, 1 Year 3 Years Expense Example, with Redemption, 3 Years 5 Years Expense Example, with Redemption, 5 Years 10 Years Expense Example, with Redemption, 10 Years Strategy [Heading] Strategy Narrative [Text Block] Risk [Heading] Risk [Text Block] Bar Chart and Performance Table [Heading] Performance Narrative [Text Block] Performance Information Illustrates Variability of Returns [Text] Performance Availability Website Address [Text] Performance Past Does Not Indicate Future [Text] Bar Chart [Heading] Bar Chart Closing [Text Block] Year to Date Return, Label Bar Chart, Year to Date Return, Date Bar Chart, Year to Date Return Highest Quarterly Return, Label Highest Quarterly Return, Date Highest Quarterly Return Lowest Quarterly Return, Label Lowest Quarterly Return, Date Lowest Quarterly Return Performance Table Heading Performance Table Uses Highest Federal Rate Performance Table Not Relevant to Tax Deferred Performance Table Explanation after Tax Higher Performance Table Closing [Text Block] 1 Year 5 Years 10 Years Objective, Secondary [Text Block] Shareholder Fees Column [Text] Maximum Cumulative Sales Charge (as a percentage of Offering Price) Maximum Deferred Sales Charge (as a percentage of Offering Price) Maximum Deferred Sales Charge (as a percentage) Redemption Fee Redemption Fee Exchange Fee (as a percentage of Amount Redeemed) Exchange Fee Maximum Account Fee (as a percentage of Assets) Shareholder Fee, Other Operating Expenses Column [Text] Fee Waiver or Reimbursement over Assets, Date of Termination Expense Footnotes [Text Block] Expenses Deferred Charges [Text Block] Expenses Range of Exchange Fees [Text Block] Expense Breakpoint Discounts [Text] Expense Breakpoint, Minimum Investment Required [Amount] Expenses Represent Both Master and Feeder [Text] Expenses Explanation of Nonrecurring Account Fee [Text] Other Expenses, New Fund, Based on Estimates [Text] Acquired Fund Fees and Expenses, Based on Estimates [Text] Expenses Other Expenses Had Extraordinary Expenses Been Included [Text] Expenses Restated to Reflect Current [Text] Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] Expense Example by Year [Heading] Expense Example by, Year, Caption [Text] Expense Example, No Redemption Narrative [Text Block] Expense Example, No Redemption, By Year, Caption [Text] Expense Example, No Redemption, 1 Year 1 Year Expense Example, No Redemption, 3 Years 3 Years Expense Example, No Redemption, 5 Years 5 Years Expense Example, No Redemption, 10 Years 10 Years Expense Example Footnotes [Text Block] Expense Example Closing [Text Block] Strategy Portfolio Concentration [Text] Risk Footnotes [Text Block] Risk Closing [Text Block] Risk Caption Risk Column [Text] Performance One Year or Less [Text] Performance Additional Market Index [Text] Performance Availability Phone [Text] Bar Chart Narrative [Text Block] Bar Chart Does Not Reflect Sales Loads [Text] Annual Return Caption [Text] Caption Annual Return, Column [Text] Column Annual Return, Inception Date Inception Date Annual Return 1990 Annual Return 1991 Annual Return 1992 Annual Return 1993 Annual Return 1994 Annual Return 1995 Annual Return 1996 Annual Return 1997 Annual Return 1998 Annual Return 1999 Annual Return 2000 Annual Return 2001 Annual Return 2002 Annual Return 2003 Annual Return 2004 Annual Return 2005 Annual Return 2006 Annual Return 2007 Annual Return 2008 Annual Return 2009 Annual Return 2010 Annual Return 2011 Annual Return 2012 Annual Return 2013 Annual Return 2014 Annual Return 2015 Annual Return 2016 Annual Return 2017