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Label Element Value
PRIMECAP Odyssey Stock Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading PRIMECAP Odyssey Stock Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The PRIMECAP Odyssey Stock Fund seeks to provide long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption [Text] 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 [Text Block] rr_PortfolioTurnoverTextBlock
The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 4% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 4.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund invests primarily in the common stocks of U.S. companies. The Fund invests at least 80% of its assets in stocks (the Fund will provide its shareholders with at least 60 days’ prior notice of any change in this non-fundamental investment policy). The Fund may invest in stocks across all market sectors and market capitalizations, though it has historically invested primarily in large- and mid-capitalization companies. Because of the bottom-up selection process of PRIMECAP Management Company (the “Advisor”), the Fund may maintain a significantly overweight or underweight position in a particular sector relative to the S&P 500® index, a market capitalization-weighted index of 500 large-capitalization stocks commonly used to represent the U.S. equity market, at any time. The Fund may also invest substantial assets in foreign securities through depository receipts or stocks traded on U.S. or foreign exchanges.
The Advisor, through its fundamental research, seeks to identify stocks with attractive growth prospects that are trading at reasonable valuations. The Advisor looks for companies that, in its judgment, will grow faster and/or will be more profitable than their current market valuations suggest and for companies with asset values that are not adequately reflected in their stock prices. The Advisor may sell a stock if its market price appears to have risen above its fundamental value, if other securities appear to be more favorably priced, if the reasons for which the stock was purchased no longer hold true, or for other reasons. The Advisor maintains a long-term focus and attempts to identify stocks that it believes will outperform the S&P 500® index over a three- to five-year time frame.
Risk [Heading] rr_RiskHeading Principal Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following performance information indicates some of the risks of investing in the Fund by showing changes in the Fund’s performance over time. The bar chart below illustrates the Fund’s total return for each of the last ten calendar years. The table below illustrates the Fund’s average annual return over time compared with a domestic broad-based securities market index. The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Unlike the Fund’s returns, the index returns do not reflect any deductions for fees, expenses, or taxes. For additional information on the index, please see “Index Description” on page 38 of the statutory prospectus. Updated performance is available on the Fund’s website at www.primecap.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following performance information indicates some of the risks of investing in the Fund by showing changes in the Fund’s performance over time.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.primecap.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Return
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
During the period shown in the bar chart, the Fund’s highest quarterly return was +17.39% for the quarter ended December 31, 2020, and the lowest quarterly return was -25.66% for the quarter ended March 31, 2020.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns as of December 31, 2023
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
PRIMECAP Odyssey Stock Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock You may lose money by investing in the Fund.
PRIMECAP Odyssey Stock Fund | Stock Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Stock market risk. 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.
PRIMECAP Odyssey Stock Fund | Manager Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Manager risk. The chance that, as a result of poor security selection by the Advisor, the Fund may underperform relative to its benchmarks or other funds with similar investment objectives.
PRIMECAP Odyssey Stock Fund | Investment Style Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Investment style risk. The chance that returns from the mix of small-, mid-, and large-cap stocks in the Fund’s portfolio will trail returns from the overall stock market. Historically, small- and mid-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall stock market, and they often perform quite differently. Additionally, from time to time, growth stocks may be more volatile than the overall stock market.
PRIMECAP Odyssey Stock Fund | Sector-Focus Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Sector-focus risk. Investing a significant portion of the Fund’s assets in one sector of the market exposes the Fund to greater market risk and potential monetary losses than if those assets were spread among various sectors. If the Fund’s portfolio is overweighted in a certain sector, any negative development affecting that sector will have a greater impact on the Fund than a fund that is not overweighted in that sector. As of October 31, 2023, investments in the health care sector represented more than 25% of the Fund's net assets.
PRIMECAP Odyssey Stock Fund | Asset Concentration Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Asset concentration risk. The chance that, because the Fund tends to invest a high percentage of its assets in its largest holdings, the Fund's performance may be hurt disproportionately by the poor performance of relatively few stocks.
PRIMECAP Odyssey Stock Fund | Foreign Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign securities risk. The chance that the value of foreign securities will be adversely affected by the political and economic environments and other overall economic conditions in the countries where the Fund invests. Investing in foreign securities involves: country risk, which is the chance that domestic events - such as political upheaval, financial troubles, corruption, or natural disasters - will weaken a country’s securities markets; and currency risk, which is the chance that the value of a foreign investment, measured in U.S. dollars, will decrease because of unfavorable changes in currency exchange rates. Foreign companies are generally subject to different legal and accounting standards than U.S. companies, and foreign financial intermediaries may be subject to less supervision and regulation than U.S. financial firms.
PRIMECAP Odyssey Stock Fund | Small- And Mid-Cap Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and mid-cap stocks risk. The chance that small- and mid-cap stocks may trade less frequently or in more limited volume than those of larger, more established companies; may fluctuate in value more; and, as a group, may suffer more severe price declines during periods of generally declining stock prices.
PRIMECAP Odyssey Stock Fund | S&P 500® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel S&P 500® index (reflects no deduction for fees, expenses, or taxes)
1 Year rr_AverageAnnualReturnYear01 26.29%
5 Years rr_AverageAnnualReturnYear05 15.69%
10 Years rr_AverageAnnualReturnYear10 12.03%
Since Inception rr_AverageAnnualReturnSinceInception 9.96%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 01, 2004
PRIMECAP Odyssey Stock Fund | PRIMECAP Odyssey Stock Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol POSKX
Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.12%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.67%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 68
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 214
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 373
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 835
Annual Return 2014 rr_AnnualReturn2014 15.04%
Annual Return 2015 rr_AnnualReturn2015 1.68%
Annual Return 2016 rr_AnnualReturn2016 12.80%
Annual Return 2017 rr_AnnualReturn2017 25.96%
Annual Return 2018 rr_AnnualReturn2018 (7.14%)
Annual Return 2019 rr_AnnualReturn2019 27.14%
Annual Return 2020 rr_AnnualReturn2020 9.97%
Annual Return 2021 rr_AnnualReturn2021 25.11%
Annual Return 2022 rr_AnnualReturn2022 (10.86%)
Annual Return 2023 rr_AnnualReturn2023 21.23%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.39%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.66%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 21.23%
5 Years rr_AverageAnnualReturnYear05 13.58%
10 Years rr_AverageAnnualReturnYear10 11.30%
Since Inception rr_AverageAnnualReturnSinceInception 10.47%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 01, 2004
PRIMECAP Odyssey Stock Fund | PRIMECAP Odyssey Stock Fund | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 18.53%
5 Years rr_AverageAnnualReturnYear05 11.32%
10 Years rr_AverageAnnualReturnYear10 9.86%
Since Inception rr_AverageAnnualReturnSinceInception 9.63%
PRIMECAP Odyssey Stock Fund | PRIMECAP Odyssey Stock Fund | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 14.43%
5 Years rr_AverageAnnualReturnYear05 10.61%
10 Years rr_AverageAnnualReturnYear10 9.11%
Since Inception rr_AverageAnnualReturnSinceInception 8.95%
PRIMECAP Odyssey Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading PRIMECAP Odyssey Growth Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The PRIMECAP Odyssey Growth Fund seeks to provide long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption [Text] 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 [Text Block] rr_PortfolioTurnoverTextBlock
The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 7% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 7.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund invests primarily in the common stocks of U.S. companies, emphasizing those companies with the potential for above average earnings growth. The Fund may invest in stocks across all market sectors and market capitalizations. Although it has historically invested primarily in large- and mid-capitalization companies, it has also invested a significant portion of its assets in small-capitalization stocks. Because of the bottom-up stock selection process of PRIMECAP Management Company (the “Advisor”), the Fund may maintain a significantly overweight or underweight position in a particular sector relative to the S&P 500® index, a market capitalization-weighted index of 500 large-capitalization stocks commonly used to represent the U.S. equity market, at any time. The Fund may also invest substantial assets in foreign securities through depository receipts or stocks traded on U.S. or foreign exchanges.
The Advisor, through its fundamental research, seeks to identify stocks that have above average growth aspects or attributes that may contribute to accelerated earnings growth in the foreseeable future. Catalysts for growth may include new products, new markets, new management, restructuring, a structural shift in demand or supply, or other changes in industry dynamics. These stocks typically provide little current income. The Advisor looks for companies that, in its judgment, will grow faster and/or will be more profitable than their current market valuations suggest and for companies with asset values that are not adequately reflected in their stock prices. The Advisor may sell a stock if its market price appears to have risen above its fundamental value, if other securities appear to be more favorably priced, if the reasons for which the stock was purchased no longer hold true, or for other reasons. The Advisor maintains a long-term focus and attempts to identify stocks that it believes will outperform the S&P 500® index over a three- to five-year time frame.
Risk [Heading] rr_RiskHeading Principal Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following performance information indicates some of the risks of investing in the Fund by showing changes in the Fund’s performance over time. The bar chart below illustrates the Fund’s total return for each of the last ten calendar years. The table below illustrates the Fund’s average annual return over time compared with a domestic broad-based securities market index. The Fund’s past performance, before and after taxes, is not necessarily an
indication of how the Fund will perform in the future. Unlike the Fund’s returns, the index returns do not reflect any deductions for fees, expenses, or taxes. For additional information on the index, please see “Index Description” on page 38 of the statutory prospectus. Updated performance is available on the Fund’s website at www.primecap.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following performance information indicates some of the risks of investing in the Fund by showing changes in the Fund’s performance over time.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.primecap.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Return
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
During the period shown in the bar chart, the Fund’s highest quarterly return was 23.61% for the quarter ended June 30, 2020, and the lowest quarterly return was -23.77% for the quarter ended March 31, 2020.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns as of December 31, 2023
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deductions for fees, expenses, or taxes)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
PRIMECAP Odyssey Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock You may lose money by investing in the Fund.
PRIMECAP Odyssey Growth Fund | Stock Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Stock market risk. 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.
PRIMECAP Odyssey Growth Fund | Manager Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Manager risk. The chance that, as a result of poor security selection by the Advisor, the Fund may underperform relative to its benchmarks or other funds with similar investment objectives.
PRIMECAP Odyssey Growth Fund | Investment Style Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Investment style risk. The chance that returns from the mix of small-, mid-, and large-cap stocks in the Fund’s portfolio will trail returns from the overall stock market. Historically, small- and mid-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall stock market, and they often perform quite
differently. Additionally, from time to time, growth stocks may be more volatile than the overall stock market.
PRIMECAP Odyssey Growth Fund | Growth Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Growth stocks risk. The chance that returns from growth stocks in the Fund’s portfolio will trail returns from the overall stock market. Growth stocks are likely to be more volatile in price than the stock market as a whole. Historically, growth funds have tended to outperform the market as a whole in rising markets and underperform the market as a whole in declining markets. Of course, there is no guarantee that this pattern will continue in the future.
PRIMECAP Odyssey Growth Fund | Asset Concentration Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Asset concentration risk. The chance that, because the Fund tends to invest a high percentage of its assets in its largest holdings, the Fund's performance may be hurt disproportionately by the poor performance of relatively few stocks.
PRIMECAP Odyssey Growth Fund | Foreign Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign securities risk. The chance that the value of foreign securities will be adversely affected by the political and economic environments and other overall economic conditions in the countries where the Fund invests. Investing in foreign securities involves: country risk, which is the chance that domestic events - such as political upheaval, financial troubles, corruption, or natural disasters - will weaken a country’s securities markets; and currency risk, which is the chance that the value of a foreign investment, measured in U.S. dollars, will decrease because of unfavorable changes in currency exchange rates. Foreign companies are generally subject to different legal and accounting standards than U.S. companies, and foreign financial intermediaries may be subject to less supervision and regulation than U.S. financial firms.
PRIMECAP Odyssey Growth Fund | Small- And Mid-Cap Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and mid-cap stocks risk. The chance that small- and mid-cap stocks may trade less frequently or in more limited volume than those of larger, more established companies; may fluctuate in value more; and, as a group, may suffer more severe price declines during periods of generally declining stock prices.
PRIMECAP Odyssey Growth Fund | S&P 500® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel S&P 500® index (reflects no deductions for fees, expenses, or taxes)
1 Year rr_AverageAnnualReturnYear01 26.29%
5 Years rr_AverageAnnualReturnYear05 15.69%
10 Years rr_AverageAnnualReturnYear10 12.03%
Since Inception rr_AverageAnnualReturnSinceInception 9.96%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 01, 2004
PRIMECAP Odyssey Growth Fund | PRIMECAP Odyssey Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol POGRX
Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
Annual Return 2014 rr_AnnualReturn2014 13.92%
Annual Return 2015 rr_AnnualReturn2015 6.18%
Annual Return 2016 rr_AnnualReturn2016 8.42%
Annual Return 2017 rr_AnnualReturn2017 32.05%
Annual Return 2018 rr_AnnualReturn2018 (4.51%)
Annual Return 2019 rr_AnnualReturn2019 23.97%
Annual Return 2020 rr_AnnualReturn2020 16.77%
Annual Return 2021 rr_AnnualReturn2021 18.54%
Annual Return 2022 rr_AnnualReturn2022 (14.35%)
Annual Return 2023 rr_AnnualReturn2023 23.87%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 23.61%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.77%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 23.87%
5 Years rr_AverageAnnualReturnYear05 12.73%
10 Years rr_AverageAnnualReturnYear10 11.65%
Since Inception rr_AverageAnnualReturnSinceInception 11.13%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 01, 2004
PRIMECAP Odyssey Growth Fund | PRIMECAP Odyssey Growth Fund | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 20.35%
5 Years rr_AverageAnnualReturnYear05 9.98%
10 Years rr_AverageAnnualReturnYear10 9.98%
Since Inception rr_AverageAnnualReturnSinceInception 10.18%
PRIMECAP Odyssey Growth Fund | PRIMECAP Odyssey Growth Fund | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 16.55%
5 Years rr_AverageAnnualReturnYear05 9.88%
10 Years rr_AverageAnnualReturnYear10 9.42%
Since Inception rr_AverageAnnualReturnSinceInception 9.57%
PRIMECAP Odyssey Aggressive Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading PRIMECAP Odyssey Aggressive Growth Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The PRIMECAP Odyssey Aggressive Growth Fund seeks to provide long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption [Text] 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 [Text Block] rr_PortfolioTurnoverTextBlock
The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 5% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 5.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees Total Annual Fund Operating Expenses do not correlate to the Ratio of Expenses to Average Net Assets in the Financial Highlights section of the statutory prospectus, which reflects the operating expenses of the Fund and does not include acquired fund fees and expenses.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund invests primarily in the common stocks of U.S. companies, emphasizing those companies with prospects for rapid earnings growth. The Fund may invest in stocks across all market sectors and market capitalizations and has historically invested significant portions of its assets in mid- and small-capitalization companies. Because of the bottom-up stock selection process of PRIMECAP Management Company (the “Advisor”), the Fund may maintain a significantly overweight or underweight position in a particular sector relative to the S&P 500® index, a market capitalization-weighted index of 500 large-capitalization stocks commonly used to represent the U.S. equity market, at any time. The Fund may also invest substantial assets in foreign securities through depository receipts or stocks traded on U.S. or foreign exchanges.
The Advisor, through its fundamental research, seeks to identify stocks that are poised for rapid earnings growth. Catalysts for the desired growth may include new products, new markets, new management, restructuring, a structural shift in demand or supply, or other changes in industry dynamics. These stocks typically provide little or no current income. The Advisor looks for companies that, in its judgment, will grow faster and/or will be more profitable than their current market valuations suggest and for companies with asset values that are not adequately reflected in their stock prices. The Advisor may sell a stock if its market price appears to have risen above its fundamental value, if other securities appear to be more favorably priced, if the reasons for which the stock was purchased no longer hold true, or for other reasons. The Advisor maintains a long-term focus and attempts to identify stocks that it believes will outperform the S&P 500® index over a three- to five-year time frame.
Risk [Heading] rr_RiskHeading Principal Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following performance information indicates some of the risks of investing in the Fund by showing changes in the Fund’s performance over time. The bar chart below illustrates the Fund’s total return for each of the last ten calendar years. The table below illustrates the Fund’s average annual return over time compared with a domestic broad-based securities market index. The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Unlike the Fund’s returns, the index returns do not reflect any deductions for fees, expenses, or taxes. For additional information on the index, please see “Index Description” on page 38 of the statutory prospectus. Updated performance is available on the Fund’s website at www.primecap.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following performance information indicates some of the risks of investing in the Fund by showing changes in the Fund’s performance over time.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.primecap.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Return
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
During the period shown in the bar chart, the Fund’s highest quarterly return was +28.84% for the quarter ended June 30, 2020, and the lowest quarterly return was -22.47% for the quarter ended March 31, 2020.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns as of December 31, 2023
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
PRIMECAP Odyssey Aggressive Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock You may lose money by investing in the Fund.
PRIMECAP Odyssey Aggressive Growth Fund | Stock Market Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Stock market risk. 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.
PRIMECAP Odyssey Aggressive Growth Fund | Manager Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Manager risk. The chance that, as a result of poor security selection by the Advisor, the Fund may underperform relative to its benchmarks or other funds with similar investment objectives.
PRIMECAP Odyssey Aggressive Growth Fund | Investment Style Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Investment style risk. The chance that returns from the mix of small- and mid-cap stocks in the Fund’s portfolio will trail returns from the overall stock market. Historically, these stocks have been more volatile in price than the large-cap stocks that dominate the overall stock market, and they often perform quite differently. Additionally, from time to time, growth stocks may be more volatile than the overall stock market.
PRIMECAP Odyssey Aggressive Growth Fund | Growth Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Growth stocks risk. The chance that returns from growth stocks in the Fund’s portfolio will trail returns from the overall stock market. Growth stocks are likely to be more volatile in price than the stock market as a whole. Historically, growth funds have tended to outperform the market as a whole in rising markets and underperform the market as a whole in declining markets. Of course, there is no guarantee that this pattern will continue in the future.
PRIMECAP Odyssey Aggressive Growth Fund | Sector-Focus Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Sector-focus risk. Investing a significant portion of the Fund’s assets in one sector of the market exposes the Fund to greater market risk and potential monetary losses than if those assets were spread among various sectors. If the Fund’s portfolio is overweighted in a certain sector, any negative development affecting that sector will have a greater impact on the Fund than a fund that is not overweighted in that sector. As of October 31, 2023, investments in the health care and information technology sectors each represented more than 25% of the Fund's net assets.
PRIMECAP Odyssey Aggressive Growth Fund | Asset Concentration Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Asset concentration risk. The chance that, because the Fund tends to invest a high percentage of its assets in its largest holdings, the Fund's performance may be hurt disproportionately by the poor performance of relatively few stocks.
PRIMECAP Odyssey Aggressive Growth Fund | Foreign Securities Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign securities risk. The chance that the value of foreign securities will be adversely affected by the political and economic environments and other overall economic conditions in the countries where the Fund invests. Investing in foreign securities involves: country risk, which is the chance that domestic events - such as political upheaval, financial troubles, corruption, or natural disasters - will weaken a country’s securities markets; and currency risk, which is the chance that the value of a foreign investment, measured in U.S. dollars, will decrease because of unfavorable changes in currency exchange rates. Foreign companies are generally subject to different legal and accounting standards than U.S. companies, and foreign financial intermediaries may be subject to less supervision and regulation than U.S. financial firms.
PRIMECAP Odyssey Aggressive Growth Fund | Small- And Mid-Cap Stocks Risk Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and mid-cap stocks risk. The chance that small- and mid-cap stocks may trade less frequently or in more limited volume than those of larger, more established companies; may fluctuate in value more; and, as a group, may suffer more severe price declines during periods of generally declining stock prices.
PRIMECAP Odyssey Aggressive Growth Fund | S&P 500® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel S&P 500® index (reflects no deduction for fees, expenses, or taxes)
1 Year rr_AverageAnnualReturnYear01 26.29%
5 Years rr_AverageAnnualReturnYear05 15.69%
10 Years rr_AverageAnnualReturnYear10 12.03%
Since Inception rr_AverageAnnualReturnSinceInception 9.96%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 01, 2004
PRIMECAP Odyssey Aggressive Growth Fund | PRIMECAP Odyssey Aggressive Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol POAGX
Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.66% [1]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
Annual Return 2014 rr_AnnualReturn2014 16.55%
Annual Return 2015 rr_AnnualReturn2015 4.56%
Annual Return 2016 rr_AnnualReturn2016 11.73%
Annual Return 2017 rr_AnnualReturn2017 33.59%
Annual Return 2018 rr_AnnualReturn2018 (6.93%)
Annual Return 2019 rr_AnnualReturn2019 23.50%
Annual Return 2020 rr_AnnualReturn2020 29.00%
Annual Return 2021 rr_AnnualReturn2021 9.38%
Annual Return 2022 rr_AnnualReturn2022 (24.03%)
Annual Return 2023 rr_AnnualReturn2023 25.03%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 28.84%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.47%)
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 25.03%
5 Years rr_AverageAnnualReturnYear05 10.60%
10 Years rr_AverageAnnualReturnYear10 10.85%
Since Inception rr_AverageAnnualReturnSinceInception 12.21%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 01, 2004
PRIMECAP Odyssey Aggressive Growth Fund | PRIMECAP Odyssey Aggressive Growth Fund | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 23.44%
5 Years rr_AverageAnnualReturnYear05 8.63%
10 Years rr_AverageAnnualReturnYear10 9.17%
Since Inception rr_AverageAnnualReturnSinceInception 11.20%
PRIMECAP Odyssey Aggressive Growth Fund | PRIMECAP Odyssey Aggressive Growth Fund | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 15.92%
5 Years rr_AverageAnnualReturnYear05 8.30%
10 Years rr_AverageAnnualReturnYear10 8.65%
Since Inception rr_AverageAnnualReturnSinceInception 10.53%
[1] Total Annual Fund Operating Expenses do not correlate to the Ratio of Expenses to Average Net Assets in the Financial Highlights section of the statutory prospectus, which reflects the operating expenses of the Fund and does not include acquired fund fees and expenses.