Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GABELLI INVESTOR FUNDS INC
Prospectus Date	rr_ProspectusDate	Apr. 29, 2020
THE GABELLI ABC FUND
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	SUMMARY OF THE FUND
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks to achieve total returns that are attractive to investors in various market conditions without excessive risk of capital loss.
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 and hold shares of the Fund.
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 rate may indicate higher transaction costs and may result in higher taxes when the Fund’s 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 278% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	278.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Expense Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This 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:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests primarily in securities of domestic and foreign issuers that Gabelli Funds, LLC, the Fund’s investment adviser (the “Adviser”), believes provide attractive opportunities for appreciation or investment income. The Adviser seeks to limit excessive risk of capital loss by utilizing various investment strategies, including investing in value oriented common stocks, i.e., common stocks that trade at a significant discount to the Adviser’s assessment of their “private market value” (the value informed investors would be willing to pay to acquire the entire company), virtually risk free U.S.Treasury Bills, and by utilizing certain “arbitrage” strategies. The Fund’s use of arbitrage may be described as investing in “event” driven situations such as announced mergers, acquisitions, and reorganizations. When a company agrees to be acquired by another company, its stock price often quickly rises to just below the stated acquisition price. If the Adviser, through extensive research, determines that the acquisition is likely to be consummated on schedule at the stated acquisition price, the Fund may purchase the selling company’s securities, offering the Fund the possibility of generous returns relative to cash equivalents with a limited risk of excessive loss of capital. The Fund may hold a significant portion of its assets in cash in anticipation of arbitrage opportunities. The Fund may invest up to 40% of its total assets in securities of non-U.S. issuers. The Fund may invest up to 25% of its assets in lower quality fixed income securities, including up to 5% of its assets in securities of issuers that are in default, in order to seek higher income and capital appreciation. For additional information about selection of investments suitable for the Fund, see page 7 of the prospectus. In selecting investments for the Fund, the Adviser considers a number of factors, including: the Adviser’s own evaluations of the “private market value” of the underlying assets and business of the company. Private market value is the value the Adviser believes informed investors would be willing to pay to acquire the entire company, the interest or dividend income generated by the securities, the potential for capital appreciation of the securities, the prices of the securities relative to other comparable securities, whether the securities are entitled to the benefits of sinking funds or other protective conditions, the existence of any anti-dilution protections or guarantees of the security, and the diversification of the Fund’s portfolio as to issuers. The Adviser also evaluates the issuer’s free cash flow and long term earnings trends. Finally, the Adviser looks for a catalyst: something in the company’s industry, indigenous to the company, or in the company’s country that will surface additional value. The Adviser expects that, in accordance with the Fund’s investment objective, it will invest the Fund’s assets in a more conservative manner than it would in a small capitalization growth fund. For example, it may utilize fixed income securities and hedging strategies to reduce the risk of capital loss to a greater extent than it does in most other equity funds managed by the Adviser. As a result, the Fund’s total return is not expected to be as high as traditional equity funds in periods of significant appreciation in the equity markets.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	You may want to invest in the Fund if: you favor a conservative approach to investments and returns you seek stability of principal more than growth of capital The Fund’s share price will fluctuate with changes in the market value of the Fund’s portfolio securities. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. When you sell Fund shares, they may be worth more or less than what you paid for them; you may lose money by investing in the Fund. The principal risks presented by the Fund are: Equity Risk.    Equity risk is the risk that the prices of the securities held by the Fund will change due to general market and economic conditions, perceptions regarding the industries in which the companies issuing the securities participate, and the issuer companies’ particular circumstances. Event Driven Risk.    Event driven investments involve the risk that certain of the events driving the investment may not happen or the market may react differently than expected to the anticipated transaction. In addition, although an event may occur or is announced, it may be renegotiated, terminated or involve a longer time frame than originally contemplated. Event driven investment transactions are also subject to the risk of overall market movements. Any one of these risks could cause the Fund to experience investment losses impacting its shares negatively. Coronavirus (“COVID-19”) and Global Health Events.    COVID-19 and concerns about its rapid spread and infections have severely impacted business activity in virtually all economies, markets, and sectors and negatively impacted the value of many financial and other assets. The duration of the COVID-19 outbreak and its effects cannot be determined with certainty. These events could have a significant impact on the Fund’s performance, as well as the performance and viability of issuers in which it invests. Foreign Securities Risk.    Investments in foreign securities involve risks relating to political, social, and economic developments abroad, as well as risks resulting from the differences between the regulations to which U.S. and foreign issuers and markets are subject. These risks include expropriation, differing accounting and disclosure standards, currency exchange risks, settlement difficulties, market illiquidity, difficulties enforcing legal rights, and greater transaction costs. These risks are more pronounced in the securities of companies located in emerging markets. Hedging Risk.    The success of hedging depends on the Adviser’s ability to predict movements in the prices of the hedged securities and market fluctuations. The Adviser may not be able to perfectly correlate changes in the market value of securities, and the prices of the corresponding options, or futures. The Adviser may have difficulty selling or buying futures contracts and options when it chooses, and there may be certain restrictions on trading futures contracts and options. Interest Rate Risk.    Investments in dividend and interest paying securities involve interest rate risk. When interest rates decline, the value of such securities generally rises. Conversely, when interest rates rise, the value of such securities generally declines. The Fund may be subject to a greater risk of rising interest rates due to the current period of historically low interest rates. There is a possibility that interest rates may rise in the future. Issuer Risk.    The value of a security may decline for a number of reasons that directly relate to an issuer, such as management performance, financial leverage, and reduced demand for the issuer’s goods or services, as well as the historical and prospective earnings of the issuer and the value of its assets or factors unrelated to the issuer’s value, such as investor perception. Lower Rated Securities.    Lower rated securities may involve major risk exposures such as increased sensitivity to interest rate and economic changes, and the market to sell such securities may be limited. These securities are often referred to in the financial press as “junk bonds.” Investments in lower rated securities may also include securities of issuers that are in default. Investments in securities of issuers in default present even greater risk exposure for the Fund. Management Risk.    If the portfolio manager is incorrect in his assessment of the growth prospects of the securities the Fund holds, then the value of the Fund’s shares may decline. Non-Diversification Risk.    As a non-diversified mutual fund, more of the Fund’s assets may be focused in the common stocks of a small number of issuers, which may make the value of the Fund’s shares more sensitive to changes in the market value of a single issuer or industry and more susceptible to risks associated with a single economic, market, political or regulatory occurrence than shares of a diversified mutual fund. Portfolio Turnover Risk.    High portfolio turnover may result in increased transaction costs to the Fund, which may result in higher fund expenses and lower total returns. The sale of portfolio securities also may result in the recognition of capital gain, which will be taxable to shareholders when distributed to them, or loss. Short Sale Risk.    Short positions in equity securities are generally considered to be more risky than long positions since the theoretical potential loss in a short position is unlimited, while the maximum loss from a long position is equal to its original purchase price.
Risk Lose Money [Text]	rr_RiskLoseMoney	When you sell Fund shares, they may be worth more or less than what you paid for them; you may lose money by investing in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Non-Diversification Risk.    As a non-diversified mutual fund, more of the Fund’s assets may be focused in the common stocks of a small number of issuers, which may make the value of the Fund’s shares more sensitive to changes in the market value of a single issuer or industry and more susceptible to risks associated with a single economic, market, political or regulatory occurrence than shares of a diversified mutual fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table that follow provide an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one year, five years, and ten years compared with those of broad based securities market indices. As with all mutual funds, the Fund’s past performance (before and after taxes) does not predict how the Fund will perform in the future. Updated information on the Fund’s results can be obtained by visiting www.gabelli.com.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table that follow provide an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for one year, five years, and ten years compared with those of broad based securities market indices.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gabelli.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all mutual funds, the Fund’s past performance (before and after taxes) does not predict how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	THE GABELLI ABC FUND (Total Returns for Class AAA Shares for the Years Ended December 31)
Bar Chart Narrative [Text Block]	rr_BarChartNarrativeTextBlock
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the calendar years shown in the bar chart, the highest return for a quarter was 3.07% (quarter ended March 31, 2012), and the lowest return for a quarter was (3.33)% (quarter ended September 30, 2011).
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the years ended December 31, 2019)
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 the investor’s tax situation and may differ from those shown. 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, including Roth IRAs and SEP IRAs (collectively, “IRAs”).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class AAA shares and after-tax returns for other classes will vary due to the differences in expenses.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some instances, the “Return After Taxes on Distributions and Sale of Fund Shares” may be greater than “Return Before Taxes” because the investor is assumed to be able to use the capital loss from the sale of Fund shares to offset other taxable gains.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	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. In some instances, the “Return After Taxes on Distributions and Sale of Fund Shares” may be greater than “Return Before Taxes” because the investor is assumed to be able to use the capital loss from the sale of Fund shares to offset other taxable gains. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. 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, including Roth IRAs and SEP IRAs (collectively, “IRAs”). After-tax returns are shown only for Class AAA shares and after-tax returns for other classes will vary due to the differences in expenses.
THE GABELLI ABC FUND | Class AAA Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of redemption or offering price, whichever is lower)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends (as a percentage of amount invested)	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee (as a percentage of amount redeemed for shares held 7 days or less)	rr_RedemptionFeeOverRedemption	2.00%
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (Rule 12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.14%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.68%
1 Year	rr_ExpenseExampleYear01	$ 69
3 Years	rr_ExpenseExampleYear03	218
5 Years	rr_ExpenseExampleYear05	379
10 Years	rr_ExpenseExampleYear10	$ 847
2010	rr_AnnualReturn2010	4.11%
2011	rr_AnnualReturn2011	1.93%
2012	rr_AnnualReturn2012	5.15%
2013	rr_AnnualReturn2013	4.92%
2014	rr_AnnualReturn2014	1.15%
2015	rr_AnnualReturn2015	2.32%
2016	rr_AnnualReturn2016	3.08%
2017	rr_AnnualReturn2017	2.20%
2018	rr_AnnualReturn2018	0.20%
2019	rr_AnnualReturn2019	4.80%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.07%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.33%)
Past One Year	rr_AverageAnnualReturnYear01	4.80%
Past Five Years	rr_AverageAnnualReturnYear05	2.51%
Past Ten Years	rr_AverageAnnualReturnYear10	2.97%
THE GABELLI ABC FUND | Advisor Class Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of redemption or offering price, whichever is lower)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends (as a percentage of amount invested)	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee (as a percentage of amount redeemed for shares held 7 days or less)	rr_RedemptionFeeOverRedemption	2.00%
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (Rule 12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.14%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.93%
1 Year	rr_ExpenseExampleYear01	$ 95
3 Years	rr_ExpenseExampleYear03	296
5 Years	rr_ExpenseExampleYear05	515
10 Years	rr_ExpenseExampleYear10	$ 1,143
Past One Year	rr_AverageAnnualReturnYear01	4.45%
Past Five Years	rr_AverageAnnualReturnYear05	2.24%
Past Ten Years	rr_AverageAnnualReturnYear10	2.71%
THE GABELLI ABC FUND | Return After Taxes on Distributions | Class AAA Shares
Risk/Return:	rr_RiskReturnAbstract
Past One Year	rr_AverageAnnualReturnYear01	3.67%
Past Five Years	rr_AverageAnnualReturnYear05	1.67%
Past Ten Years	rr_AverageAnnualReturnYear10	2.18%
THE GABELLI ABC FUND | Return After Taxes on Distributions and Sale of Fund Shares | Class AAA Shares
Risk/Return:	rr_RiskReturnAbstract
Past One Year	rr_AverageAnnualReturnYear01	2.93%
Past Five Years	rr_AverageAnnualReturnYear05	1.63%
Past Ten Years	rr_AverageAnnualReturnYear10	2.06%
THE GABELLI ABC FUND | ICE Bank of America Merrill Lynch 3 Month U.S. Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Past One Year	rr_AverageAnnualReturnYear01	2.28%
Past Five Years	rr_AverageAnnualReturnYear05	1.07%
Past Ten Years	rr_AverageAnnualReturnYear10	0.58%
THE GABELLI ABC FUND | Lipper U.S. Treasury Money Market Fund Average
Risk/Return:	rr_RiskReturnAbstract
Past One Year	rr_AverageAnnualReturnYear01	1.89%
Past Five Years	rr_AverageAnnualReturnYear05	0.77%
Past Ten Years	rr_AverageAnnualReturnYear10	0.39%
THE GABELLI ABC FUND | S&P Long-Only Merger Arbitrage Index
Risk/Return:	rr_RiskReturnAbstract
Past One Year	rr_AverageAnnualReturnYear01	6.70%
Past Five Years	rr_AverageAnnualReturnYear05	4.25%
Past Ten Years	rr_AverageAnnualReturnYear10	4.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 17, 2008