Vanguard PRIMECAP Fund Performance Management - Retail Prospectus [Member] - Vanguard PRIMECAP Fund	Sep. 30, 2025
Prospectus [Line Items]
Bar Chart and Performance Table [Heading]	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Annual Total Returns</span>
Performance Past Does Not Indicate Future [Text]	<span style="font-family:Arial;font-size:9.5pt;"> Keep in mind that </span><span style="font-family:Arial;font-size:9.5pt;">the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future.</span>
Performance Information Illustrates Variability of Returns [Text]	<span style="font-family:Arial;font-size:9.5pt;">The following bar chart and table show the Fund’s historical performance and 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 broad-based securities market index and one or more</span><span style="font-family:Arial;font-size:9.5pt;line-height:11.5pt;"> </span><span style="font-family:Arial;font-size:9.5pt;">additional indexes with similar investment characteristics as the Fund.</span>
Bar Chart [Heading]	<span style="font-family:Arial;font-size:8pt;font-weight:bold;">Annual Total Returns — Vanguard PRIMECAP Fund Investor Shares</span>
Bar Chart Closing [Text Block]	During the periods shown in the bar chart, the highest and lowest returns for a calendar quarter were:
Performance Table Heading	<span style="font-family:Arial;font-size:8.5pt;font-weight:bold;">Average Annual Total Returns for Periods Ended December 31, 2025</span>
Performance Table Uses Highest Federal Rate	<span style="color:#000000;font-family:Arial;font-size:9.5pt;">When after-tax returns are calculated, it is </span><span style="color:#000000;font-family:Arial;font-size:9.5pt;">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. </span>
Performance Table Not Relevant to Tax Deferred	<span style="color:#000000;font-family:Arial;font-size:9.5pt;">not relevant for </span><span style="color:#000000;font-family:Arial;font-size:9.5pt;">a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. </span>
Performance Table Explanation after Tax Higher	<span style="color:#000000;font-family:Arial;font-size:9.5pt;">Also, figures captioned </span><span style="color:#000000;font-family:Arial;font-size:9.5pt;font-style:italic;">Return After Taxes on Distributions and Sale of Fund Shares</span><span style="color:#000000;font-family:Arial;font-size:9.5pt;"> 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.</span>
Performance Table Closing [Text Block]	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.
Performance Availability Website Address [Text]	<span style="font-family:Arial;font-size:9.5pt;font-style:italic;">vanguard.com/performance</span>
Investor Shares
Prospectus [Line Items]
Highest Quarterly Return, Label [Optional Text]	<span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;">Highest</span>
Highest Quarterly Return	17.25%
Highest Quarterly Return, Date	Jun. 30, 2020
Lowest Quarterly Return, Label [Optional Text]	<span style="color:#000000;font-family:Arial;font-size:8pt;margin-left:0.0pt;">Lowest</span>
Lowest Quarterly Return	(20.17%)
Lowest Quarterly Return, Date	Mar. 31, 2020