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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Feb. 28, 2013
Registrant Name dei_EntityRegistrantName Vanguard World Fund
Central Index Key dei_EntityCentralIndexKey 0000052848
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jun. 17, 2013
Document Effective Date dei_DocumentEffectiveDate Jun. 17, 2013
Vanguard Mega Cap Growth Index Fund | ETF
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Jun. 17, 2013
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization growth stocks in the United States.
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 ETF 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 16%.

PortfolioTurnover, Rate rr_PortfolioTurnoverRate 16.00%
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 MegaCap Growth ETF with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invest $10,000 in MegaCap Growth ETF. This example assumes that MegaCap Growth ETF provides 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:
Expense Example Closing rr_ExpenseExampleClosingTextBlock

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

Strategy: rr_StrategyHeading Primary Investment Strategies
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mega Cap Growth Index, which represents the growth companies of the CRSP US Mega Cap Index. The Index is a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of mega-capitalization growth stocks. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.
Risk: rr_RiskHeading Primary Risks
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. The Fund's target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

Investment style risk, which is the chance that returns from large-capitalization growth stocks will trail returns from the overall stock market. Large-cap growth stocks tend to go through cycles of doing better-or worse-than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

Because ETF Shares are traded on an exchange, they are subject to additional risks:

The Fund's ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

Although the Fund's ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

Trading of the Fund's ETF Shares on NYSE Arca may be halted by the activation of individual or marketwide 'circuit breakers'(which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund's ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or to protect investors.

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
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Mega Cap Growth Index Fund ETF 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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares 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.
Bar Chart Footnotes rr_BarChartFootnotesTextBlock

1 The year-to-date return as of the most recent calendar quarter, which ended on March 31, 2013 was 8.63%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 15.24% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -23.23% (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 March 31, 2013
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, 2012
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
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 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 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.
Vanguard Mega Cap Growth Index Fund | Institutional
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Jun. 17, 2013
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization growth stocks in the United States.
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 Institutional 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 16%.

PortfolioTurnover, Rate rr_PortfolioTurnoverRate 16.00%
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 Institutional 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:
Strategy: rr_StrategyHeading Primary Investment Strategies
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mega Cap Growth Index, which represents the growth companies of the CRSP US Mega Cap Index. The Index is a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of mega-capitalization growth stocks. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.
Risk: rr_RiskHeading Primary Risks
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. The Fund's target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

Investment style risk, which is the chance that returns from large-capitalization growth stocks will trail returns from the overall stock market. Large-cap growth stocks tend to go through cycles of doing better-or worse-than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

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
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Mega Cap Growth Index Fund Institutional 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 Institutional Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Institutional Shares 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.
Bar Chart Footnotes rr_BarChartFootnotesTextBlock

1 The year-to-date return as of the most recent calendar quarter, which ended on March 31, 2013 was 8.62%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 15.27% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -12.60% (quarter ended June 30, 2010 ).
Year to Date Return Label rr_YearToDateReturnLabel The year-to-date return as of the most recent calendar quarter, which ended on March 31, 2013
Highest Quarterly Return Label rr_HighestQuarterlyReturnLabel (quarter ended June 30, 2009 )
Lowest Quarterly Return Label rr_LowestQuarterlyReturnLabel (quarter ended June 30, 2010 )
Bar Chart and Performance Table: rr_PerformanceTableHeading Average Annual Total Returns for Periods Ended December 31, 2012
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflect no deduction for fees, expenses, or taxes)
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 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 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.
Vanguard Mega Cap Growth Index Fund | Vanguard Mega Cap Growth Index Fund - Institutional 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 fund account balances below $10,000) rr_MaximumAccountFee 20
Management Expenses rr_ManagementFeesOverAssets 0.06%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.09%
1 YEAR rr_ExpenseExampleNoRedemptionYear01 9
3 YEAR rr_ExpenseExampleNoRedemptionYear03 29
5 YEAR rr_ExpenseExampleNoRedemptionYear05 51
10 YEAR rr_ExpenseExampleNoRedemptionYear10 115
Annual Return Inception Date rr_AnnualReturnInceptionDate Apr. 03, 2008
2009 rr_AnnualReturn2009 35.10%
2010 rr_AnnualReturn2010 14.69%
2011 rr_AnnualReturn2011 3.07%
2012 rr_AnnualReturn2012 17.25%
Date rr_BarChartYearToDateReturnDate Mar. 31, 2013
Year to Date Return rr_BarChartYearToDateReturn 8.62%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.27%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2010
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (12.60%)
One Year rr_AverageAnnualReturnYear01 17.25%
Since Inception rr_AverageAnnualReturnSinceInception 5.29%
Inception Date rr_AverageAnnualReturnInceptionDate Apr. 03, 2008
Vanguard Mega Cap Growth Index Fund | Vanguard Mega Cap Growth Index Fund - ETF Shares
  
Risk/Return: rr_RiskReturnAbstract  
Management Expenses rr_ManagementFeesOverAssets 0.08%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.12%
1 YEAR rr_ExpenseExampleNoRedemptionYear01 12
3 YEAR rr_ExpenseExampleNoRedemptionYear03 39
5 YEAR rr_ExpenseExampleNoRedemptionYear05 68
10 YEAR rr_ExpenseExampleNoRedemptionYear10 154
Annual Return Inception Date rr_AnnualReturnInceptionDate Dec. 17, 2007
2008 rr_AnnualReturn2008 (36.47%)
2009 rr_AnnualReturn2009 35.09%
2010 rr_AnnualReturn2010 14.67%
2011 rr_AnnualReturn2011 3.05%
2012 rr_AnnualReturn2012 17.23%
Date rr_BarChartYearToDateReturnDate Mar. 31, 2013
Year to Date Return rr_BarChartYearToDateReturn 8.63%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.24%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (23.23%)
One Year rr_AverageAnnualReturnYear01 17.23%
Five Years rr_AverageAnnualReturnYear05 3.52%
Since Inception rr_AverageAnnualReturnSinceInception 3.89%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 17, 2007
Vanguard Mega Cap Index Fund | ETF
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Jun. 17, 2013
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization stocks in the United States.
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 ETF 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 19%.
PortfolioTurnover, Rate rr_PortfolioTurnoverRate 19.00%
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 MegaCap ETF with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invest $10,000 in MegaCap ETF. This example assumes that MegaCap ETF provides 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:
Expense Example Closing rr_ExpenseExampleClosingTextBlock

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

Strategy: rr_StrategyHeading Primary Investment Strategies
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mega Cap Index. The Index is a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of mega-capitalization stocks. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.
Risk: rr_RiskHeading Primary Risks
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. The Fund's target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

Investment style risk, which is the chance that returns from large-capitalization stocks will trail returns from the overall stock market. Large-cap stocks tend to go through cycles of doing better-or worse-than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

Because ETF Shares are traded on an exchange, they are subject to additional risks:

The Fund's ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

Although the Fund's ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

Trading of the Fund's ETF Shares on NYSE Arca may be halted by the activation of individual or marketwide 'circuit breakers'(which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund's ETF Shares may also be halted if (1)the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or to protect investors.

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
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Mega Cap Index Fund ETF 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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF 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 (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 March 31, 2013 was 10.29%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 15.54% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -21.46% (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 March 31, 2013
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, 2012
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
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 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 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.
Vanguard Mega Cap Index Fund | Institutional
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Jun. 17, 2013
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization stocks in the United States.
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 Institutional 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 19%.
PortfolioTurnover, Rate rr_PortfolioTurnoverRate 19.00%
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 Institutional 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:
Strategy: rr_StrategyHeading Primary Investment Strategies
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mega Cap Index. The Index is a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of mega-capitalization stocks. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.
Risk: rr_RiskHeading Primary Risks
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. The Fund's target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

Investment style risk, which is the chance that returns from large-capitalization stocks will trail returns from the overall stock market. Large-cap stocks tend to go through cycles of doing better-or worse-than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

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
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Mega Cap Index Fund Institutional 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 Institutional Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Institutional 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 (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 March 31, 2013 was 10.31%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 15.55% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -13.36% (quarter ended September 30, 2011 ).
Year to Date Return Label rr_YearToDateReturnLabel The year-to-date return as of the most recent calendar quarter, which ended on March 31, 2013
Highest Quarterly Return Label rr_HighestQuarterlyReturnLabel (quarter ended June 30, 2009 )
Lowest Quarterly Return Label rr_LowestQuarterlyReturnLabel (quarter ended September 30, 2011 )
Bar Chart and Performance Table: rr_PerformanceTableHeading Average Annual Total Returns for Periods Ended December 31, 2012
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
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 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 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.
Vanguard Mega Cap Index Fund | Vanguard Mega Cap Index Fund - Institutional 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 fund account balances below $10,000) rr_MaximumAccountFee 20
Management Expenses rr_ManagementFeesOverAssets 0.05%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.08%
1 YEAR rr_ExpenseExampleNoRedemptionYear01 8
3 YEAR rr_ExpenseExampleNoRedemptionYear03 26
5 YEAR rr_ExpenseExampleNoRedemptionYear05 45
10 YEAR rr_ExpenseExampleNoRedemptionYear10 103
Annual Return Inception Date rr_AnnualReturnInceptionDate Feb. 22, 2008
2009 rr_AnnualReturn2009 25.46%
2010 rr_AnnualReturn2010 13.84%
2011 rr_AnnualReturn2011 2.34%
2012 rr_AnnualReturn2012 16.13%
Date rr_BarChartYearToDateReturnDate Mar. 31, 2013
Year to Date Return rr_BarChartYearToDateReturn 10.31%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.55%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (13.36%)
One Year rr_AverageAnnualReturnYear01 16.13%
Since Inception rr_AverageAnnualReturnSinceInception 3.37%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 22, 2008
Vanguard Mega Cap Index Fund | Vanguard Mega Cap Index Fund - ETF Shares
  
Risk/Return: rr_RiskReturnAbstract  
Management Expenses rr_ManagementFeesOverAssets 0.08%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.12%
1 YEAR rr_ExpenseExampleNoRedemptionYear01 12
3 YEAR rr_ExpenseExampleNoRedemptionYear03 39
5 YEAR rr_ExpenseExampleNoRedemptionYear05 68
10 YEAR rr_ExpenseExampleNoRedemptionYear10 154
Annual Return Inception Date rr_AnnualReturnInceptionDate Dec. 17, 2007
2008 rr_AnnualReturn2008 (36.08%)
2009 rr_AnnualReturn2009 25.43%
2010 rr_AnnualReturn2010 13.81%
2011 rr_AnnualReturn2011 2.32%
2012 rr_AnnualReturn2012 16.11%
Date rr_BarChartYearToDateReturnDate Mar. 31, 2013
Year to Date Return rr_BarChartYearToDateReturn 10.29%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.54%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (21.46%)
One Year rr_AverageAnnualReturnYear01 16.11%
Five Years rr_AverageAnnualReturnYear05 1.63%
Since Inception rr_AverageAnnualReturnSinceInception 1.93%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 17, 2007
Vanguard Mega Cap Value Index Fund | ETF
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Jun. 17, 2013
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization value stocks in the United States.
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 ETF 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 17%.

PortfolioTurnover, Rate rr_PortfolioTurnoverRate 17.00%
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 MegaCap Value ETF with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invest $10,000 in MegaCap Value ETF. This example assumes that MegaCap Value ETF provides 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:
Expense Example Closing rr_ExpenseExampleClosingTextBlock

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

Strategy: rr_StrategyHeading Primary Investment Strategies
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mega Cap Value Index, which represents the value companies of the CRSP US Mega Cap Index. The Index is a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of mega-capitalization value stocks. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.
Risk: rr_RiskHeading Primary Risks
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. The Fund's target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

Investment style risk, which is the chance that returns from large-capitalization value stocks will trail returns from the overall stock market. Large-cap value stocks tend to go through cycles of doing better-or worse-than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

Because ETF Shares are traded on an exchange, they are subject to additional risks:

The Fund's ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

Although the Fund's ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

Trading of the Fund's ETF Shares on NYSE Arca may be halted by the activation of individual or marketwide 'circuit breakers'(which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund's ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or to protect investors.

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
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Mega Cap Value Index Fund ETF 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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares 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.
Bar Chart Footnotes rr_BarChartFootnotesTextBlock

1 The year-to-date return as of the most recent calendar quarter, which ended on March 31, 2013 was 11.76%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 16.12% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -19.64% (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 March 31, 2013
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, 2012
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
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 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 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.
Vanguard Mega Cap Value Index Fund | Institutional
  
Risk/Return: rr_RiskReturnAbstract  
Prospectus Date rr_ProspectusDate Jun. 17, 2013
Risk/Return rr_RiskReturnHeading Risk/Return
Investment objective: rr_ObjectiveHeading Investment Objective
Investment objective rr_ObjectivePrimaryTextBlock

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization value stocks in the United States.
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 Institutional 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 17%.

PortfolioTurnover, Rate rr_PortfolioTurnoverRate 17.00%
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 Institutional 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:
Strategy: rr_StrategyHeading Primary Investment Strategies
StrategyNarrative rr_StrategyNarrativeTextBlock

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mega Cap Value Index, which represents the value companies of the CRSP US Mega Cap Index. The Index is a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of mega-capitalization value stocks. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.
Risk: rr_RiskHeading Primary Risks
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. The Fund's target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

Investment style risk, which is the chance that returns from large-capitalization value stocks will trail returns from the overall stock market. Large-cap value stocks tend to go through cycles of doing better-or worse-than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

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
Bar Chart rr_BarChartHeading Annual Total Returns - Vanguard Mega Cap Value Index Fund Institutional 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 Institutional Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Institutional Shares 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.
Bar Chart Footnotes rr_BarChartFootnotesTextBlock

1 The year-to-date return as of the most recent calendar quarter, which ended on March 31, 2013 was 11.78%
Bar Chart Closing rr_BarChartClosingTextBlock

During the periods shown in the bar chart, the highest return for a calendar quarter was 16.08% (quarter ended June 30, 2009 ), and the lowest return for a quarter was -16.97% (quarter ended March 31, 2009 ).
Year to Date Return Label rr_YearToDateReturnLabel The year-to-date return as of the most recent calendar quarter, which ended on March 31, 2013
Highest Quarterly Return Label rr_HighestQuarterlyReturnLabel (quarter ended June 30, 2009 )
Lowest Quarterly Return Label rr_LowestQuarterlyReturnLabel (quarter ended March 31, 2009 )
Bar Chart and Performance Table: rr_PerformanceTableHeading Average Annual Total Returns for Periods Ended December 31, 2012
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
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 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 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.
Vanguard Mega Cap Value Index Fund | Vanguard Mega Cap Value Index Fund - Institutional 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 fund account balances below $10,000) rr_MaximumAccountFee 20
Management Expenses rr_ManagementFeesOverAssets 0.04%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.08%
1 YEAR rr_ExpenseExampleNoRedemptionYear01 8
3 YEAR rr_ExpenseExampleNoRedemptionYear03 26
5 YEAR rr_ExpenseExampleNoRedemptionYear05 45
10 YEAR rr_ExpenseExampleNoRedemptionYear10 103
Annual Return Inception Date rr_AnnualReturnInceptionDate Mar. 05, 2008
2009 rr_AnnualReturn2009 16.47%
2010 rr_AnnualReturn2010 13.00%
2011 rr_AnnualReturn2011 1.49%
2012 rr_AnnualReturn2012 14.99%
Date rr_BarChartYearToDateReturnDate Mar. 31, 2013
Year to Date Return rr_BarChartYearToDateReturn 11.78%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 16.08%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2009
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (16.97%)
One Year rr_AverageAnnualReturnYear01 14.99%
Since Inception rr_AverageAnnualReturnSinceInception 1.72%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 05, 2008
Vanguard Mega Cap Value Index Fund | Vanguard Mega Cap Value Index Fund - ETF Shares
  
Risk/Return: rr_RiskReturnAbstract  
Management Expenses rr_ManagementFeesOverAssets 0.08%
12b-1 Distribution Fee rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_NetExpensesOverAssets 0.12%
1 YEAR rr_ExpenseExampleNoRedemptionYear01 12
3 YEAR rr_ExpenseExampleNoRedemptionYear03 39
5 YEAR rr_ExpenseExampleNoRedemptionYear05 68
10 YEAR rr_ExpenseExampleNoRedemptionYear10 154
Annual Return Inception Date rr_AnnualReturnInceptionDate Dec. 17, 2007
2008 rr_AnnualReturn2008 (35.78%)
2009 rr_AnnualReturn2009 16.47%
2010 rr_AnnualReturn2010 12.98%
2011 rr_AnnualReturn2011 1.47%
2012 rr_AnnualReturn2012 14.95%
Date rr_BarChartYearToDateReturnDate Mar. 31, 2013
Year to Date Return rr_BarChartYearToDateReturn 11.76%
Bar Chart Highest Quarterly Return Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Bar Chart Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 16.12%
Bar Chart Lowest Quarter Return Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Bar Chart Lowest Quarter Return rr_BarChartLowestQuarterlyReturn (19.64%)
One Year rr_AverageAnnualReturnYear01 14.95%
Five Years rr_AverageAnnualReturnYear05 (0.29%)
Since Inception rr_AverageAnnualReturnSinceInception (0.06%)
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 17, 2007
MSCI US Large Cap 300 Index | Vanguard Mega Cap Index Fund | Vanguard Mega Cap Index Fund - Institutional Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 16.21%
Since Inception rr_AverageAnnualReturnSinceInception 3.42%
MSCI US Large Cap 300 Index | Vanguard Mega Cap Index Fund | Vanguard Mega Cap Index Fund - ETF Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 16.21%
Five Years rr_AverageAnnualReturnYear05 1.70%
Since Inception rr_AverageAnnualReturnSinceInception 2.01%
MSCI US Large Cap Value Index | Vanguard Mega Cap Value Index Fund | Vanguard Mega Cap Value Index Fund - Institutional Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 15.04%
Since Inception rr_AverageAnnualReturnSinceInception 1.71%
MSCI US Large Cap Value Index | Vanguard Mega Cap Value Index Fund | Vanguard Mega Cap Value Index Fund - ETF Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 15.04%
Five Years rr_AverageAnnualReturnYear05 (0.27%)
Since Inception rr_AverageAnnualReturnSinceInception (0.03%)
MSCI US Large Cap Growth Index | Vanguard Mega Cap Growth Index Fund | Vanguard Mega Cap Growth Index Fund - Institutional Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 17.36%
Since Inception rr_AverageAnnualReturnSinceInception 5.36%
MSCI US Large Cap Growth Index | Vanguard Mega Cap Growth Index Fund | Vanguard Mega Cap Growth Index Fund - ETF Shares
  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 17.36%
Five Years rr_AverageAnnualReturnYear05 3.61%
Since Inception rr_AverageAnnualReturnSinceInception 3.99%