Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 01, 2012
DREYFUS FUND INC (Prospectus Summary) | DREYFUS FUND INC
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Fund Summary
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The fund seeks long-term capital growth consistent with the preservation of capital.
Investment Objective, Secondary	rr_ObjectiveSecondaryTextBlock	Current income is a secondary investment objective.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.
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 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 67.60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	67.60%
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The 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 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, based on these assumptions your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategy
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	To pursue its goals, the fund primarily invests in common stocks issued by U.S. companies. The fund may invest up to 20% of its assets in foreign securities. In choosing stocks, the fund's portfolio managers focus on large-capitalization companies with strong positions in their industries and a catalyst that can trigger a price increase (such as a corporate restructuring or change in management). The portfolio managers use fundamental analysis to create a broadly diversified portfolio comprised of growth stocks, value stocks and stocks that exhibit characteristics of both investment styles. The portfolio managers attempt to measure a security's instrinsic value by analyzing "real" data (company financials, economic outlook, etc.) and other factors (management, industry conditions, competition, etc.) and select stocks based on value, growth and financial profile.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. It is not a complete investment program. The fund's share price fluctuates, sometimes dramatically, which means you could lose money. o Risks of stock investing. Stocks generally fluctuate more in value than bonds and may decline significantly over short time periods. There is the chance that stock prices overall will decline because stock markets tend to move in cycles, with periods of rising prices and falling prices. The market value of a stock may decline due to general weakness in the stock market or because of factors that affect the company or its particular industry. o Growth and value stock risk. By investing in a mix of growth and value companies, the fund assumes the risks of both. Investors often expect growth companies to increase their earnings at a certain rate. If these expectations are not met, investors can punish the stocks inordinately, even if earnings do increase. In addition, growth stocks typically lack the dividend yield that can cushion stock prices in market downturns. Value stocks involve the risk that they may never reach their expected full market value, either because the market fails to recognize the stock's intrinsic worth, or the expected value was misgauged. They also may decline in price even though in theory they are already undervalued. o Large cap stock risk. To the extent the fund invests in large capitalization stocks, the fund may underperform funds that invest primarily in the stocks of lower quality, smaller capitalization companies during periods when the stocks of such companies are in favor. o Market sector risk. The fund may significantly overweight or underweight certain companies, industries or market sectors, which may cause the fund's performance to be more or less sensitive to developments affecting those companies, industries or sectors. o Foreign investment risk. Special risks associated with investments in foreign issuers include exposure to currency fluctuations, less liquidity, less developed or less efficient trading markets, lack of comprehensive company information, political and economic instability and differing auditing and legal standards.
Risk, Lose Money	rr_RiskLoseMoney	The fund's share price fluctuates, sometimes dramatically, which means you could lose money.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the fund is not a bank deposit. It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The following bar chart and table provide some indication of the risks of investing in the fund. The table compares the average annual total returns of the fund's shares to those of a broad measure of market performance. The fund's past performance (before and after taxes) is no guarantee of future results. More recent performance information may be available at www.dreyfus.com.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart and table provide some indication of the risks of investing in the fund.
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.dreyfus.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The fund's past performance (before and after taxes) is no guarantee of future results.
Bar Chart, Heading	rr_BarChartHeading	Year-by-Year Total Returns as of 12/31 each year (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	The bar chart shows changes in the performance of the fund's shares from year to year.
Bar Chart, Closing	rr_BarChartClosingTextBlock	Best Quarter               Q3, 2009: 18.17%           Worst Quarter              Q4, 2008: -22.66%
Index No Deduction for Fees, Expenses, Taxes	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 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 the investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table, Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns (as of 12/31/11)
DREYFUS FUND INC (Prospectus Summary) | DREYFUS FUND INC | S&P 500® Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	S&P 500® Index reflects no deduction for fees, expenses or taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	2.09%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.25%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.92%
DREYFUS FUND INC (Prospectus Summary) | DREYFUS FUND INC | DREYFUS FUND INC
Risk Return [Abstract]	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets	0.65%
Other expenses	rr_OtherExpensesOverAssets	0.12%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.77%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	79
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	246
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	428
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	954
Annual Return 2002	rr_AnnualReturn2002	(22.15%)
Annual Return 2003	rr_AnnualReturn2003	24.94%
Annual Return 2004	rr_AnnualReturn2004	8.46%
Annual Return 2005	rr_AnnualReturn2005	5.28%
Annual Return 2006	rr_AnnualReturn2006	15.58%
Annual Return 2007	rr_AnnualReturn2007	7.89%
Annual Return 2008	rr_AnnualReturn2008	(38.21%)
Annual Return 2009	rr_AnnualReturn2009	28.75%
Annual Return 2010	rr_AnnualReturn2010	16.30%
Annual Return 2011	rr_AnnualReturn2011	(5.05%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.17%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.66%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Fund returns before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(5.05%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.07%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	1.98%
DREYFUS FUND INC (Prospectus Summary) | DREYFUS FUND INC | DREYFUS FUND INC | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Fund returns after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(5.21%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.59%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	1.39%
DREYFUS FUND INC (Prospectus Summary) | DREYFUS FUND INC | DREYFUS FUND INC | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Fund returns after taxes on distributions and sale of fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(3.06%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.93%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	1.66%