Alger International Opportunities Fund Investment Risks - Class A B C Shares [Member] - Alger International Opportunities Fund	Oct. 31, 2025
Investment Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Investment Risk – An investment in the Fund is subject to investment risk, including the possible loss of the entire principal amount that you invest.
Market Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	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, trade disputes and changes in trade regulations, civil unrest, recessions, or other events could have a significant impact on the Fund and its investments.
Equity Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	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.
Foreign Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Foreign Securities Risk – The Fund’s performance will be influenced by political, social and economic factors affecting investments in foreign companies. Special risks associated with investments in foreign companies include exposure to currency fluctuations, lack of liquidity, potential for market manipulation, less developed or less efficient trading markets, limited access to reliable capital, lack of comprehensive company information, political instability, differing audit, regulatory, and legal standards and lack of financial reporting standards. Additionally, events and evolving conditions in certain markets or regions may alter the risk profile of investments tied to those markets or regions. This may cause investments tied to such markets or regions to become riskier or more volatile, even when investments in such markets or regions were perceived as comparatively stable historically. In addition, foreign companies with securities listed on U.S. exchanges may be delisted if they do not meet U.S. accounting standards and auditor oversight requirements, which may decrease the liquidity and value of the securities.
Emerging Markets Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Emerging Markets Risk – The Fund may invest in issuers located in emerging markets, and therefore may be exposed to the economies, industries, securities and currency markets of such countries, which may be adversely affected by protectionist trade policies, a slow U.S. economy, political and social instability, regional and global conflicts, terrorism and war, including actions that are contrary to the interests of the United States. Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets. The Fund, individually or in combination with other shareholders, may have limited rights and remedies against emerging market issuers.
Frontier Markets Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Frontier Markets Risk – The Fund may invest in issuers located in frontier countries. Frontier markets are those emerging markets that are considered to be among the smallest, least mature and least liquid, and as a result, may be more likely to experience inflation, political turmoil and rapid changes in economic conditions than more developed and traditional emerging markets. Investments in frontier markets may be subject to a greater risk of loss than investments in more developed and traditional emerging markets. Frontier markets often have less uniformity in accounting, auditing and financial reporting requirements, unreliable securities valuations and greater risk associated with custody of securities. Economic, political and currency risks may be more pronounced with respect to investments in frontier markets than in emerging markets.
Small Number of Holdings Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Small Number of Holdings Risk – Under normal circumstances, the Fund invests in a small number of issuers. Therefore, the Fund’s performance may be more vulnerable to changes in the market value of a single issuer and more susceptible to risks associated with a single economic, political, or regulatory occurrence than a fund that has a higher number of holdings.
Sector Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	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.
Information Technology Sector Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	●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.
Communication Services Sector Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	●Communication Services Sector Risk – Communication services companies are particularly vulnerable to the potential obsolescence of products and services due to technological advancement and the innovation of competitors. Companies in the communication services sector may also be affected by other competitive pressures, such as pricing competition, as well as research and development costs, substantial capital requirements and government regulation. Additionally, fluctuating domestic and international demand, shifting demographics and often unpredictable changes in consumer tastes can drastically affect a communication services company’s profitability. While all companies may be susceptible to network security breaches, certain companies in the communication services sector may be particular targets of hacking and potential theft of proprietary or consumer information or disruptions in service, which could have a material adverse effect on their businesses.
Industrials Sector Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	●Industrials Sector Risk – The Fund may have a significant portion of its assets invested in securities of companies in the industrials sector. Industrial companies are affected by supply and demand both for their specific product or service and for industrials sector products in general. Government regulation, world events, exchange rates and economic conditions, technological developments and liabilities for environmental damage and general civil liabilities will likewise affect the performance of these companies. Aerospace and defense companies, a component of the industrials sector, can be significantly affected by government spending policies because companies involved in this industry rely, to a significant extent, on U.S. and foreign government demand for their products and services.
Financials Sector Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	●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.
Growth Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	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.
Small Cap Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Small Cap Securities Risk – There may be greater risk in investing in companies with small market capitalizations rather than larger, more established companies owing to such factors as more limited product lines or financial resources or lack of management depth. It may also be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.
Cash Position Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Cash Position Risk – At times, the Fund may hold up to 15% of its net assets in cash (and cash equivalents), which may underperform relative to equity securities.
Risk Lose Money [Member]
Prospectus [Line Items]
Risk [Text Block]	The Fund’s share price may go down, which means you could lose money.
Risk Not Insured Depository Institution [Member]
Prospectus [Line Items]
Risk [Text Block]	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.