Alger Concentrated Equity Fund Investment Strategy - Class A C Shares [Member] - Alger Concentrated Equity Fund	Oct. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Principal Investment Strategy</span>
Strategy Narrative [Text Block]	Under normal circumstances, the Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities of large-cap companies that the Manager believes demonstrate promising growth potential. For these purposes, “large-cap companies” are those companies that, at the time of purchase of the securities, have total market capitalization within the range of companies included in the Russell 1000 Growth Index. At December 31, 2025, the companies in this index ranged from $1.03 billion to $4.53 trillion. Equity securities include common or preferred stocks that are listed on U.S. exchanges. The Fund will invest at least 25% of its total assets in companies focused in the following group of related industries: software, technology hardware storage and peripherals, semiconductors and semiconductor equipment, information technology services, electronic equipment instruments and components, communications equipment, broadline retail and interactive media and services, as classified by third party sources. From time to time, the Fund may have 25% or more of its total assets invested in any one of these industries. The Fund intends to invest a substantial portion of its assets in a smaller number of issuers. Generally, the Fund will own no more than 30 holdings. As a result, the Fund is a non-diversified investment company, which means the performance results of any one position may have a greater impact on the Fund’s performance. Fund holdings may differ from this number for any reason. Such reasons may be, among others, because of extreme market volatility, such as when the Fund has entered a temporary defensive position. Additionally, the Fund may temporarily exceed the stated number of holdings when it acquires a new holding and determines that it is in the best interests of shareholders to sell an existing holding over a period of time, instead of immediately selling the entire holding.The Fund may sell a stock when it reaches a target price, it fails to perform as expected, or other opportunities appear more attractive. As a result, the Fund may engage in active trading of portfolio securities.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, consumer discretionary and communication services sectors. For the purpose of categorizing companies, sectors are a broader category than industries and industries comprise sectors.The Fund can also invest in privately placed securities, which are securities acquired in non-public offerings for which there is no readily available market.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 15% of the Fund’s net assets.