Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	PARNASSUS FUNDS
Prospectus Date	rr_ProspectusDate	May 01, 2016
Parnassus Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Parnassus Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Parnassus Fund has the overall investment objective of capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Parnassus Fund.
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)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	May 1, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Parnassus 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 68.5% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	68.50%
Expense Footnotes [Text Block]	rr_ExpenseFootnotesTextBlock	For additional information about the Parnassus Fund’s expenses, please see “Financial Highlights” in the prospectus.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Parnassus 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. Although your actual costs may be higher or lower, under these assumptions, your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Parnassus Fund invests in undervalued stocks. This Fund follows a “contrarian” strategy of seeking to invest in stocks that are currently out of favor with the financial community and are therefore, in the opinion of the Fund’s investment adviser (Adviser), deeply undervalued. The Adviser expects that if these undervalued companies are financially strong and have good prospects for the future, they will come back into favor and increase in market value. The Parnassus Fund is a “multi-cap” fund in that it can invest in companies of any size, from larger, well-established companies to smaller companies with market capitalizations below $1 billion. The Fund invests mainly in domestic stocks of companies that are financially sound and have good prospects for the future, and to a lesser extent may also invest in foreign securities of similar companies. The Fund may purchase foreign securities directly on foreign markets. The Fund avoids investing in companies engaged in the extraction, exploration, production, manufacturing or refining of fossil fuels; the Fund may invest in companies that use fossil fuel-based energy to power their operations or for other purposes. To determine a company’s prospects, the Adviser reviews the company’s income statement, cash flow statement and balance sheet, and analyzes the company’s sustainable strategic advantage and management team. Upon initial investment, a company’s stock must be trading below its intrinsic value, which means that the Adviser seeks to purchase stock trading at a discount to the Adviser’s assessment of the company’s estimated value. The Adviser also takes environmental, social and governance (“ESG”) factors into account in making investment decisions. The Fund will sell a security if the Adviser believes a company’s fundamentals will deteriorate, if it believes a company’s stock has little potential for appreciation or if the company no longer meets the Adviser’s ESG criteria.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	All investments involve risk, and investing in the Parnassus Fund is no exception. You could lose money investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time. The Fund is intended for investors who can accept that there will be fluctuations in value. Investments in the Fund are not deposits, endorsements or guarantees of any bank and are not insured by the Federal Deposit Insurance Corporation or any other government agency. The Fund’s principal risks include the following: Stock Market Risk. The Fund invests in common stocks, whose prices fluctuate in response to the fortunes of individual companies and in response to general market and economic conditions both in the U.S. and abroad. The Fund’s holdings can vary significantly from broad stock market indices. Large-Capitalization Company Risk. Large-capitalization companies may be unable to respond quickly to new competitive challenges and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion. Small- and Mid-Capitalization Company Risk. This is a “multi-cap” fund. In addition to large-capitalization companies, the Fund may invest in small- and/or mid-capitalization companies, which can be particularly sensitive to changing economic conditions since they do not have the financial resources or the well-established businesses of large-capitalization companies. Relative to the stocks of large-capitalization companies, the stocks of small- and mid-capitalization companies are often thinly traded, and purchases and sales may result in higher transaction costs. Also, small-capitalization companies tend to perform poorly during times of economic stress. Management Risk. The Adviser may be wrong in its assessment of a company’s value and/or the stocks the Fund holds may not reach what the Adviser believes are their full values. From time to time, “value” investing falls out of favor with investors, and during those periods the Fund’s relative performance may suffer. Foreign Securities Risk. The Fund may invest up to 20% of its assets in foreign securities. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market or economic developments and can perform differently from the U.S. market.
Risk Lose Money [Text]	rr_RiskLoseMoney	You could lose money investing in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	Investments in the Fund are not deposits, endorsements or guarantees of any bank and are not insured by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table that follow contain information that allows you to evaluate the Parnassus Fund’s performance using several measures, such as yearly changes in performance, best and worst quarterly returns, and average annual total returns before and after taxes compared to a broad measure of market performance. The bar chart shows the performance of the Fund’s Investor Shares, and the performance of the Fund’s Institutional Shares will differ from those shown to the extent that the classes of shares do not have the same expenses or inception date. How the Fund performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund’s website, www.parnassus.com, or by calling toll-free at (800) 999-3505.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table that follow contain information that allows you to evaluate the Parnassus Fund’s performance using several measures, such as yearly changes in performance, best and worst quarterly returns, and average annual total returns before and after taxes compared to a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 999-3505
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.parnassus.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	How the Fund performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 19.9% (quarter ended September 30, 2009), and the lowest return for a quarter was a loss of 26.6% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (%) (all periods ended December 31, 2015)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	The 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	After-tax returns 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 Investor Shares only. After-tax returns for Institutional Shares will vary.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of Fund shares.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	On the following page is a table comparing the performance of the Parnassus Fund’s two share classes with that of the S&P 500 Index and the Lipper Multi-Cap Core Average. Figures are average annual returns for the one-, five- and ten-year periods ended December 31, 2015. The table is intended to demonstrate the risk of investing in the Parnassus Fund by showing how the Fund’s average annual total returns, before and after taxes, compare with a broad measure of market performance, the S&P 500 Index, and a group of similar mutual funds, the Lipper Multi-Cap Core Average, and also how the Fund’s performance varies from year to year.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	The 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. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of Fund shares. After-tax returns are shown for Investor Shares only. After-tax returns for Institutional Shares will vary. Parnassus Fund—Institutional Shares were incepted on April 30, 2015. Performance shown prior to the inception of the Institutional Shares reflects the performance of the Parnassus Fund—Investor Shares and includes expenses that are not applicable to and are higher than those of the Institutional Shares.
Parnassus Fund | Investor Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.62%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Service Fees	rr_Component1OtherExpensesOverAssets	0.10%
All remaining other expenses	rr_Component2OtherExpensesOverAssets	0.12%
Other Expenses	rr_OtherExpensesOverAssets	0.22%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.84%	[1]
1 Year	rr_ExpenseExampleYear01	$ 86
3 Years	rr_ExpenseExampleYear03	268
5 Years	rr_ExpenseExampleYear05	466
10 Years	rr_ExpenseExampleYear10	$ 1,037
2006	rr_AnnualReturn2006	14.36%
2007	rr_AnnualReturn2007	5.43%
2008	rr_AnnualReturn2008	(34.12%)
2009	rr_AnnualReturn2009	47.94%
2010	rr_AnnualReturn2010	16.71%
2011	rr_AnnualReturn2011	(5.01%)
2012	rr_AnnualReturn2012	26.04%
2013	rr_AnnualReturn2013	34.22%
2014	rr_AnnualReturn2014	14.68%
2015	rr_AnnualReturn2015	0.26%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	19.90%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(26.60%)
One Year	rr_AverageAnnualReturnYear01	0.26%
Five Years	rr_AverageAnnualReturnYear05	13.06%
Ten Years	rr_AverageAnnualReturnYear10	9.74%
Parnassus Fund | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.62%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Service Fees	rr_Component1OtherExpensesOverAssets	none
All remaining other expenses	rr_Component2OtherExpensesOverAssets	0.08%
Other Expenses	rr_OtherExpensesOverAssets	0.08%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.70%	[1]
1 Year	rr_ExpenseExampleYear01	$ 72
3 Years	rr_ExpenseExampleYear03	224
5 Years	rr_ExpenseExampleYear05	390
10 Years	rr_ExpenseExampleYear10	$ 871
One Year	rr_AverageAnnualReturnYear01	0.37%
Five Years	rr_AverageAnnualReturnYear05	13.09%
Ten Years	rr_AverageAnnualReturnYear10	9.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 30, 2015
Parnassus Fund | Return after Taxes on Distributions | Investor Shares
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	(3.67%)
Five Years	rr_AverageAnnualReturnYear05	10.24%
Ten Years	rr_AverageAnnualReturnYear10	8.23%
Parnassus Fund | Return after Taxes on Distributions and Sale of Fund Shares | Investor Shares
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	3.52%
Five Years	rr_AverageAnnualReturnYear05	10.39%
Ten Years	rr_AverageAnnualReturnYear10	7.95%
Parnassus Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	1.39%
Five Years	rr_AverageAnnualReturnYear05	12.55%
Ten Years	rr_AverageAnnualReturnYear10	7.30%
Parnassus Fund | Lipper Multi-Cap Core Average
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	(2.14%)
Five Years	rr_AverageAnnualReturnYear05	10.14%
Ten Years	rr_AverageAnnualReturnYear10	6.19%

[1] The investment adviser has contractually agreed to reduce its investment advisory fee to the extent necessary to limit total operating expenses to 0.99% of net assets for the Parnassus Fund—Investor Shares and to 0.94% of net assets for the Parnassus Fund—Institutional Shares. This agreement will not be terminated prior to May 1, 2017, and may be continued indefinitely by the investment adviser on a year-to-year basis.