Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	THE ALGER FUNDS
Prospectus Date	rr_ProspectusDate	Feb. 28, 2025
Class A C Shares | Alger Growth and Income Fund - AC
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<span style="color:#262626;font-family:Arial;font-size:10pt;font-weight:bold;text-transform:uppercase;">Alger Growth & Income Fund</span>
Objective [Heading]	rr_ObjectiveHeading	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Investment Objective</span>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Alger Growth & Income Fund seeks to provide capital appreciation and current income.
Expense [Heading]	rr_ExpenseHeading	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Fund Fees and Expenses</span>
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 table and examples below.You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in Class A Shares of the Alger Family of Funds, including the Fund. More information about these and other discounts is available from your financial professional and in “Purchasing and Redeeming Fund Shares” on page 69 and in Appendix A – Waivers and Discounts Available from Intermediaries on page A-1 in the Fund’s Prospectus, and in the sections “Right of Accumulation (Class A Shares)” and “Letter of Intent (Class A)” beginning on page 38 of the Fund’s Statement of Additional Information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	<span style="color:#262626;font-family:Arial;font-size:9pt;font-weight:bold;">Shareholder Fees</span> <br/><span style="color:#262626;font-family:Arial;font-size:9pt;">(fees paid directly from your investment)</span>
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<span style="color:#262626;font-family:Arial;font-size:9pt;font-weight:bold;">Annual Fund Operating Expenses</span> <br/><span style="color:#262626;font-family:Arial;font-size:9pt;">(expenses that you pay each year as a percentage of the value of your investment)</span>
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Portfolio Turnover</span>
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 annual fund operating expenses or in the examples, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 1.53% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	1.53%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	Purchases of $1 million or more of Class A Shares at net asset value may be subject to a contingent deferred sales charge of 1.00% on redemptions made within 12 months of purchase.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	<span style="color:#262626;font-family:Arial;font-size:9pt;">You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least </span><span style="color:#262626;font-family:Arial;font-size:9pt;">$25,000</span><span style="color:#262626;font-family:Arial;font-size:9pt;"> in Class A Shares of the Alger Family of Funds, including the Fund.</span>
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 25,000
Expense Example [Heading]	rr_ExpenseExampleHeading	<span style="color:#0064FA;font-family:Arial;font-size:9pt;font-weight:bold;">Example</span>
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following examples are intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The examples assume 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, 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:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	<span style="color:#262626;font-family:Arial;font-size:8pt;font-weight:bold;">You would pay the following expenses if you did not redeem your shares:</span>
Strategy [Heading]	rr_StrategyHeading	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Principal Investment Strategy</span>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Fred Alger Management, LLC (the “Manager”) believes companies undergoing Positive Dynamic Change offer the best opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, rapidly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from new regulations, a new product innovation or new management.The Fund invests primarily in equity securities such as common or preferred stocks which the Manager believes offer opportunities for capital appreciation and which also pay dividends. In considering such companies, the Manager classifies them into three categories: Dividend Leaders – companies that generate high dividend yields; Dividend Growers – companies that have a history of strong and consistent dividend growth; and Kings of Cash Flow – companies that have strong potential for generating capital appreciation and the ability to return significant amounts of cash to investors as a result of their free cash flow. The Fund intends to invest at least 65% of its total assets in dividend paying equity securities. The Fund may invest up to 35% of its total assets in equity securities that do not pay dividends or in money market instruments and repurchase agreements. The Fund focuses on growing companies that, at the time of purchase of the securities, have a market capitalization equal to or greater than the market capitalization of companies included in the S&P 500 Index. This index is designed to track the performance of large-capitalization stocks. At December 31, 2024, the market capitalization of the companies in this index ranged from $6.1 billion to $3.8 trillion.The Fund may invest a significant portion of its assets in securities of companies conducting business within a single sector, as defined by third party sources, including, but not limited to, the information technology, health care, and financials sectors.The Fund may sell a stock when it reaches a target price, it fails to perform as expected, or other opportunities appear more attractive.The Fund may invest in cash (and cash equivalents) when the Fund is unable to find enough attractive long-term investments to meet its investment objective, to meet redemptions and/or when the Manager believes it is advisable to do so during times of short-term market volatility. During these times, cash (and cash equivalents) will not exceed 35% of the Fund’s net assets.
Risk [Heading]	rr_RiskHeading	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Principal Risks</span>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Performance</span>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following bar chart and the table beneath it provide some 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 the indicated periods compare with those of an appropriate broad-based securities market index that represents the overall domestic equity market. Performance in the bar chart does not reflect the effect of the sales charge imposed on purchases of Class A Shares of the Fund. If the bar chart reflected the applicable sales charges, returns would be less than those shown.The Fund’s past performance (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.alger.com.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	<span style="color:#262626;font-family:Arial;font-size:9pt;">The following bar chart and the table beneath it provide some 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 the indicated periods compare with those of an appropriate broad-based securities market index that represents the overall domestic equity market. </span>
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<span style="color:#262626;font-family:Arial;font-size:9pt;">www.alger.com</span>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	<span style="color:#262626;font-family:Arial;font-size:9pt;">The Fund’s past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.</span>
Bar Chart [Heading]	rr_BarChartHeading	<span style="color:#262626;font-family:Arial;font-size:10pt;font-weight:bold;">Annual Total Return for Class A Shares</span><span style="color:#262626;font-family:Arial;font-size:10pt;line-height:12pt;"> </span><span style="color:#262626;font-family:Arial;font-size:10pt;font-style:italic;">as of December 31 (%)</span>
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	<span style="color:#262626;font-family:Arial;font-size:9pt;">Performance in the bar chart does not reflect the effect of the sales charge imposed on purchases of Class A Shares of the Fund. If </span><span style="color:#262626;font-family:Arial;font-size:9pt;">the bar chart reflected the applicable sales charges, returns would be less than those shown.</span>
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:Q2 202019.56%Worst Quarter:Q1 2020-19.79%
Performance Table Heading	rr_PerformanceTableHeading	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Average Annual Total Return as of December 31, 2024</span>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="color:#262626;font-family:Arial;font-size:9pt;">after-tax returns are calculated using the historical highest individual federal marginal income tax rates and </span><span style="color:#262626;font-family:Arial;font-size:9pt;">do not reflect the impact of state and local taxes.</span>
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	<span style="color:#262626;font-family:Arial;font-size:9pt;">Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.</span>
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	<span style="color:#262626;font-family:Arial;font-size:9pt;">After-tax returns for Class C Shares, which are not shown, will vary from those shown for Class A Shares.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	In the foregoing table, 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. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.After-tax returns for Class C Shares, which are not shown, will vary from those shown for Class A Shares.
Class A C Shares | Alger Growth and Income Fund - AC | Risk Lose Money [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	The Fund’s share price may go down, which means you could lose money.
Class A C Shares | Alger Growth and Income Fund - AC | Risk Not Insured Depository Institution [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	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.
Class A C Shares | Alger Growth and Income Fund - AC | Investment Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Investment Risk – An investment in the Fund is subject to investment risk, including the possible loss of the entire principal amount that you invest.
Class A C Shares | Alger Growth and Income Fund - AC | Market Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Market Risk – Your investment in Fund shares represents an indirect investment in the securities owned by the Fund. The value of these securities, like other investments, may move up or down, sometimes rapidly and unpredictably. Your Fund shares at any point in time may be worth less than what you invested, even after taking into account the reinvestment of Fund dividends and distributions. Local, regional or global events such as environmental or natural disasters, war, terrorism, pandemics, outbreaks of infectious diseases, and similar public health threats, recessions, or other events could have a significant impact on the Fund and its investments.
Class A C Shares | Alger Growth and Income Fund - AC | Equity Securities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Equity Securities Risk – As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund’s price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund’s investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds. In addition, there are special risks associated with investing in preferred securities, including deferral and omission of distributions, subordination to bonds and other debt securities in a company’s capital structure, limited liquidity, limited voting rights and special redemption rights. The market value of preferred stocks is generally more sensitive to changes in interest rates than the market value of common stocks.
Class A C Shares | Alger Growth and Income Fund - AC | Growth Securities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Growth Securities Risk – Prices of growth stocks tend to be higher in relation to their companies’ earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment’s value.
Class A C Shares | Alger Growth and Income Fund - AC | Income-Producing Securities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Income-Producing Securities Risk – Companies may cut or fail to declare dividends due to market downturns or other reasons. Income producing securities may become generally less favored by market participants, potentially leading such securities to underperform the broader stock market.
Class A C Shares | Alger Growth and Income Fund - AC | Sector Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Sector Risk – The Fund may have a significant portion of its assets invested in securities of companies conducting business within a single sector, as defined by third party sources. Companies in the same sector may be similarly affected by economic, regulatory, political or market events or conditions, which may make the Fund more vulnerable to unfavorable developments in that sector than a fund that has a more diversified portfolio. Generally, the more broadly the Fund invests, the more it spreads risk and potentially reduces the risks of loss and volatility.
Class A C Shares | Alger Growth and Income Fund - AC | Information Technology Sector Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	●Information Technology Sector Risk – The Fund may have a significant portion of its assets invested in securities of technology-related companies. Therefore, the Fund may be more susceptible to particular risks that may affect companies in the information technology sector and technology-related sectors than if it were invested in a wider variety of companies in unrelated sectors. At times, the performance of such companies will lag the performance of other industries or the broader market as a whole. Certain technology related companies may face special risks that their products or services may not prove to be commercially successful. Technology related companies are also strongly affected by worldwide scientific or technological developments. As a result, their products may rapidly become obsolete. Such companies are also often subject to governmental regulation and may, therefore, be adversely affected by governmental policies. These factors may lead to limited earnings and/or failing profit margins. As a result, the value of technology related companies’ securities may fall or fail to rise. Many technology related companies’ securities have historically been more volatile than other securities, especially over the short term.
Class A C Shares | Alger Growth and Income Fund - AC | Health Care Sector Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	●Health Care Sector Risk – The Fund may have a significant portion of its assets invested in securities of healthcare companies. At times, the performance of healthcare companies will lag the performance of other industries or the broader market as a whole, and the performance of such companies may be more volatile. Healthcare companies may also be significantly affected by intense competition, aggressive pricing, government regulation, technological innovations, product obsolescence, patent considerations, product compatibility and consumer preferences.
Class A C Shares | Alger Growth and Income Fund - AC | Financials Sector Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	●Financials Sector Risk – The Fund may have a significant portion of its assets invested in securities of financial services companies, which means the Fund may be more affected by the performance of the financials sector than a fund that is more diversified. Financial services companies are subject to extensive governmental regulation which may limit both the amounts and types of loans and other financial commitments they can make, the interest rates and fees they can charge, the scope of their activities, the prices they can charge and the amount of capital they must maintain. Certain events in the financials sector may cause an unusually high degree of volatility in the financial markets, both domestic and foreign, and cause certain financial services companies to incur large losses.
Class A C Shares | Alger Growth and Income Fund - AC | Cash Position Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Cash Position Risk – At times, the Fund may hold up to 35% of its net assets in cash (and cash equivalents), which may underperform relative to equity securities.
Class A C Shares | Alger Growth and Income Fund - AC | Class A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases as a % of offering price	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum deferred sales charge (load) as a % of purchase price or redemption proceeds, whichever is lower	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Advisory Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.95%
1 Year	rr_ExpenseExampleYear01	$ 617
3 Years	rr_ExpenseExampleYear03	812
5 Years	rr_ExpenseExampleYear05	1,023
10 Years	rr_ExpenseExampleYear10	$ 1,630
2015	rr_AnnualReturn2015	1.17%
2016	rr_AnnualReturn2016	10.23%
2017	rr_AnnualReturn2017	20.65%
2018	rr_AnnualReturn2018	(4.72%)
2019	rr_AnnualReturn2019	28.91%
2020	rr_AnnualReturn2020	15.22%
2021	rr_AnnualReturn2021	30.72%
2022	rr_AnnualReturn2022	(14.11%)
2023	rr_AnnualReturn2023	23.01%
2024	rr_AnnualReturn2024	21.81%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	<span style="color:#262626;font-family:Arial;font-size:8pt;font-weight:bold;">Best Quarter:</span>
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	19.56%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	<span style="color:#262626;font-family:Arial;font-size:8pt;font-weight:bold;">Worst Quarter:</span>
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.79%)
1 Year	rr_AverageAnnualReturnYear01	15.43%
5 Years	rr_AverageAnnualReturnYear05	12.93%
10 Years	rr_AverageAnnualReturnYear10	11.74%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1996
Class A C Shares | Alger Growth and Income Fund - AC | Class C
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases as a % of offering price	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) as a % of purchase price or redemption proceeds, whichever is lower	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Advisory Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.70%
1 Year	rr_ExpenseExampleYear01	$ 273
3 Years	rr_ExpenseExampleYear03	536
5 Years	rr_ExpenseExampleYear05	923
10 Years	rr_ExpenseExampleYear10	2,008
1 Year	rr_ExpenseExampleNoRedemptionYear01	173
3 Years	rr_ExpenseExampleNoRedemptionYear03	536
5 Years	rr_ExpenseExampleNoRedemptionYear05	923
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,008
1 Year	rr_AverageAnnualReturnYear01	19.90%
5 Years	rr_AverageAnnualReturnYear05	13.30%
10 Years	rr_AverageAnnualReturnYear10	11.67%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 31, 1997
Class A C Shares | Alger Growth and Income Fund - AC | Return After Taxes on Distributions | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	15.11%
5 Years	rr_AverageAnnualReturnYear05	12.16%
10 Years	rr_AverageAnnualReturnYear10	10.67%
Class A C Shares | Alger Growth and Income Fund - AC | Return After Taxes on Distributions and Sale of Shares | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.33%
5 Years	rr_AverageAnnualReturnYear05	10.03%
10 Years	rr_AverageAnnualReturnYear10	9.21%
Class A C Shares | Alger Growth and Income Fund - AC | S&P 500 Index (reflects no deductions for fees, expenses or taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	25.02%
5 Years	rr_AverageAnnualReturnYear05	14.53%
10 Years	rr_AverageAnnualReturnYear10	13.10%

[1] Purchases of $1 million or more of Class A Shares at net asset value may be subject to a contingent deferred sales charge of 1.00% on redemptions made within 12 months of purchase.