Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	OPPENHEIMER CAPITAL APPRECIATION FUND
Prospectus Date	rr_ProspectusDate	Oct. 30, 2018
OPPENHEIMER CAPITAL APPRECIATION FUND
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<b>The Fund Summary </b>
Objective [Heading]	rr_ObjectiveHeading	<b>Investment Objective.</b>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	<b>Fees and Expenses of the Fund.</b>
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold or redeem shares of the Fund. You may qualify for sales charge discounts if you (or you and your spouse) invest, or agree to invest in the future, at least $25,000 in certain funds in the Oppenheimer family of funds. More information about these and other discounts and sales charge waivers is available from your financial professional and in the section “About Your Account” beginning on page 10 of the prospectus, in the appendix to the prospectus titled “Special Sales Charge Arrangements and Waivers” and in the section “How to Buy Shares” beginning on page 48 in the Fund’s Statement of Additional Information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	<b>Shareholder Fees </b><br/>(fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<b>Annual Fund Operating Expenses</b><br/> (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<b>Portfolio Turnover. </b>
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 rate 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 the 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 29% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	29.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you (or you and your spouse) invest, or agree to invest in the future, at least $25,000 in certain funds in the Oppenheimer family of funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 25,000
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Expenses have been restated to reflect current fees.
Expense Example [Heading]	rr_ExpenseExampleHeading	<b>Example.</b>
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example 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 a class of shares of 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. Any applicable fee waivers and/or expense reimbursements are reflected in the below examples for the first year only. Although your actual costs may be higher or lower, based on these assumptions your expenses would be as follows:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	<b>If shares are redeemed </b>
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	<b>If shares are not redeemed </b>
Strategy [Heading]	rr_StrategyHeading	<b>Principal Investment Strategies.</b>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund mainly invests in common stocks of “growth companies.” Growth companies are companies whose earnings and stock prices are expected to increase at a faster rate than the overall market. These may be newer companies or established companies of any capitalization range that the portfolio manager believes may appreciate in value over the long term. Currently, the Fund primarily focuses on established companies that are similar in size to companies in the S&P 500 Index or the Russell 1000 Growth Index. The Fund primarily invests in securities of U.S. issuers but may also invest in foreign securities. The portfolio manager looks for growth companies with stock prices that he believes are reasonable in relation to overall stock market valuations. In seeking broad diversification of the Fund’s portfolio among industries and market sectors, the portfolio manager focuses on a number of factors that may vary in particular cases and over time. Currently, the portfolio manager looks for: companies in business areas that have above-average growth potential; companies with growth rates that the portfolio manager believes are sustainable over time; and stocks with reasonable valuations relative to their growth potential. The Fund may sell the stocks of companies that the portfolio manager believes no longer meet the above criteria, but is not required to do so.
Risk [Heading]	rr_RiskHeading	<b>Principal Risks.</b>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The price of the Fund’s shares can go up and down substantially. The value of the Fund’s investments may fall due to adverse changes in the markets in which the Fund invests or because of poor investment selection, which could cause the Fund to underperform other funds with similar investment objectives. There is no assurance that the Fund will achieve its investment objective. When you redeem your shares, they may be worth less than what you paid for them. These risks mean that you can lose money by investing in the Fund. Risks of Investing in Stocks. The value of the Fund’s portfolio may be affected by changes in the stock markets. Stock markets may experience significant short-term volatility and may fall sharply at times. Adverse events in any part of the equity or fixed-income markets may have unexpected negative effects on other market segments. Different stock markets may behave differently from each other and U.S. stock markets may move in the opposite direction from one or more foreign stock markets. The prices of individual stocks generally do not all move in the same direction at the same time. A variety of factors can negatively affect the price of a particular company’s stock. These factors may include, but are not limited to: poor earnings reports, a loss of customers, litigation against the company, general unfavorable performance of the company’s sector or industry, or changes in government regulations affecting the company or its industry. To the extent that securities of a particular type are emphasized (for example foreign stocks, stocks of small- or mid-cap companies, growth or value stocks, or stocks of companies in a particular industry), fund share values may fluctuate more in response to events affecting the market for those types of securities. Industry and Sector Focus. At times the Fund may increase the relative emphasis of its investments in a particular industry or sector. The prices of stocks of issuers in a particular industry or sector may go up and down in response to changes in economic conditions, government regulations, availability of basic resources or supplies, or other events that affect that industry or sector more than others. To the extent that the Fund increases the relative emphasis of its investments in a particular industry or sector, its share values may fluctuate in response to events affecting that industry or sector. To some extent that risk may be limited by the Fund’s policy of not concentrating its investments in any one industry. Risks of Growth Investing. If a growth company’s earnings or stock price fails to increase as anticipated, or if its business plans do not produce the expected results, its securities may decline sharply. Growth companies may be newer or smaller companies that may experience greater stock price fluctuations and risks of loss than larger, more established companies. Newer growth companies tend to retain a large part of their earnings for research, development or investments in capital assets. Therefore, they may not pay any dividends for some time. Growth investing has gone in and out of favor during past market cycles and is likely to continue to do so. During periods when growth investing is out of favor or when markets are unstable, it may be more difficult to sell growth company securities at an acceptable price. Growth stocks may also be more volatile than other securities because of investor speculation. Who Is the Fund Designed For? The Fund is designed primarily for investors seeking capital appreciation over the long term. Those investors should be willing to assume the risks of short-term share price fluctuations that are typical for a fund focusing on stocks. Because of its focus on long-term growth, the Fund may be more appropriate for investors with longer term investment goals. The Fund is not designed for investors needing current income. The Fund is not a complete investment program. You should carefully consider your own investment goals and risk tolerance before investing in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	<i>These risks mean that you can lose money by investing in the Fund.</i>
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	<b>An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. </b>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<b>The Fund’s Past Performance.</b>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance (for Class A Shares) from calendar year to calendar year and by showing how the Fund’s average annual returns for the periods of time shown in the table compare with those of a broad measure of market performance. The Fund’s past investment performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Sales charges and taxes are not reflected in the bar chart and if those charges were included, returns would be less than those shown. More recent performance information is available by calling the toll-free number on the back of this prospectus and on the Fund’s website: https://www.oppenheimerfunds.com/fund/CapitalAppreciationFund
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance (for Class A Shares) from calendar year to calendar year and by showing how the Fund’s average annual returns for the periods of time shown in the table compare with those of a broad measure of market performance.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<i> https://www.oppenheimerfunds.com/fund/CapitalAppreciationFund</i>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past investment performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges and taxes are not reflected in the bar chart and if those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Sales charges and taxes are not included and the returns would be lower if they were. During the period shown, the highest return for a calendar quarter was 18.94% (2nd Qtr 09) and the lowest return for a calendar quarter was -28.10% (4th Qtr 08). For the period from January 1, 2018 to September 30, 2018 the return before sales charges and taxes was 12.90%.
Performance Table Heading	rr_PerformanceTableHeading	<b>Average Annual Total Returns </b>for the periods ended December 31, 2017
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the highest individual federal marginal income tax rates and do not reflect the impact of state or local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Your actual after-tax returns, depending on your individual tax situation, may differ from those shown and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for only one class and after-tax returns for other classes will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The following table shows the average annual total returns for each class of the Fund’s shares. After-tax returns are calculated using the highest individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Your actual after-tax returns, depending on your individual tax situation, may differ from those shown and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for only one class and after-tax returns for other classes will vary.
OPPENHEIMER CAPITAL APPRECIATION FUND | Class A
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.59%	[1]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.21%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.05%	[1]
1 Year	rr_ExpenseExampleYear01	$ 676
3 Years	rr_ExpenseExampleYear03	891
5 Years	rr_ExpenseExampleYear05	1,124
10 Years	rr_ExpenseExampleYear10	1,790
1 Year	rr_ExpenseExampleNoRedemptionYear01	676
3 Years	rr_ExpenseExampleNoRedemptionYear03	891
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,124
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,790
2008	rr_AnnualReturn2008	(45.90%)
2009	rr_AnnualReturn2009	43.58%
2010	rr_AnnualReturn2010	9.14%
2011	rr_AnnualReturn2011	(1.57%)
2012	rr_AnnualReturn2012	13.69%
2013	rr_AnnualReturn2013	29.24%
2014	rr_AnnualReturn2014	15.07%
2015	rr_AnnualReturn2015	3.22%
2016	rr_AnnualReturn2016	(2.34%)
2017	rr_AnnualReturn2017	26.53%
Year to Date Return, Label	rr_YearToDateReturnLabel	For the period from January 1, 2018 to September 30, 2018
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2018
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	12.90%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.94%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(28.10%)
1 Year	rr_AverageAnnualReturnYear01	19.25%
5 Years	rr_AverageAnnualReturnYear05	12.32%
10 Years	rr_AverageAnnualReturnYear10	5.43%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 22, 1981
OPPENHEIMER CAPITAL APPRECIATION FUND | Class C
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.59%	[1]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.21%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.80%	[1]
1 Year	rr_ExpenseExampleYear01	$ 285
3 Years	rr_ExpenseExampleYear03	571
5 Years	rr_ExpenseExampleYear05	983
10 Years	rr_ExpenseExampleYear10	2,135
1 Year	rr_ExpenseExampleNoRedemptionYear01	185
3 Years	rr_ExpenseExampleNoRedemptionYear03	571
5 Years	rr_ExpenseExampleNoRedemptionYear05	983
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,135
1 Year	rr_AverageAnnualReturnYear01	24.56%
5 Years	rr_AverageAnnualReturnYear05	12.79%
10 Years	rr_AverageAnnualReturnYear10	5.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 01, 1993
OPPENHEIMER CAPITAL APPRECIATION FUND | Class R
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.59%	[1]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.21%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.30%	[1]
1 Year	rr_ExpenseExampleYear01	$ 133
3 Years	rr_ExpenseExampleYear03	415
5 Years	rr_ExpenseExampleYear05	717
10 Years	rr_ExpenseExampleYear10	1,578
1 Year	rr_ExpenseExampleNoRedemptionYear01	133
3 Years	rr_ExpenseExampleNoRedemptionYear03	415
5 Years	rr_ExpenseExampleNoRedemptionYear05	717
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,578
1 Year	rr_AverageAnnualReturnYear01	26.19%
5 Years	rr_AverageAnnualReturnYear05	13.36%
10 Years	rr_AverageAnnualReturnYear10	5.78%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2001
OPPENHEIMER CAPITAL APPRECIATION FUND | Class Y
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.59%	[1]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.21%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.80%	[1]
1 Year	rr_ExpenseExampleYear01	$ 82
3 Years	rr_ExpenseExampleYear03	256
5 Years	rr_ExpenseExampleYear05	446
10 Years	rr_ExpenseExampleYear10	994
1 Year	rr_ExpenseExampleNoRedemptionYear01	82
3 Years	rr_ExpenseExampleNoRedemptionYear03	256
5 Years	rr_ExpenseExampleNoRedemptionYear05	446
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 994
1 Year	rr_AverageAnnualReturnYear01	26.82%
5 Years	rr_AverageAnnualReturnYear05	13.95%
10 Years	rr_AverageAnnualReturnYear10	6.40%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 03, 1997
OPPENHEIMER CAPITAL APPRECIATION FUND | Class I
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.59%	[1]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.04%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.63%	[1]
1 Year	rr_ExpenseExampleYear01	$ 65
3 Years	rr_ExpenseExampleYear03	202
5 Years	rr_ExpenseExampleYear05	352
10 Years	rr_ExpenseExampleYear10	789
1 Year	rr_ExpenseExampleNoRedemptionYear01	65
3 Years	rr_ExpenseExampleNoRedemptionYear03	202
5 Years	rr_ExpenseExampleNoRedemptionYear05	352
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 789
1 Year	rr_AverageAnnualReturnYear01	27.04%
5 Years	rr_AverageAnnualReturnYear05	14.14%
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	14.09%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 2011
OPPENHEIMER CAPITAL APPRECIATION FUND | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.14%
5 Years	rr_AverageAnnualReturnYear05	9.76%
10 Years	rr_AverageAnnualReturnYear10	4.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 22, 1981
OPPENHEIMER CAPITAL APPRECIATION FUND | Return After Taxes on Distributions and Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	12.21%
5 Years	rr_AverageAnnualReturnYear05	9.26%
10 Years	rr_AverageAnnualReturnYear10	4.07%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 22, 1981
OPPENHEIMER CAPITAL APPRECIATION FUND | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	21.83%
5 Years	rr_AverageAnnualReturnYear05	15.79%
10 Years	rr_AverageAnnualReturnYear10	8.50%
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	15.72%	[2]
OPPENHEIMER CAPITAL APPRECIATION FUND | Russell 1000 Growth Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	30.21%
5 Years	rr_AverageAnnualReturnYear05	17.33%
10 Years	rr_AverageAnnualReturnYear10	10.00%
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	16.89%	[2]

[1] Expenses have been restated to reflect current fees.

[2] From 12/29/11