Alger International Small Cap Fund - A Fees and Expenses - Class A C Shares [Member] - Alger International Small Cap Fund - A	Jun. 23, 2025 USD ($)
Prospectus [Line Items]
Expense Heading [Optional Text]	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Fund Fees and Expenses</span>
Expense Narrative [Text Block]	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 16 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 31 of the Fund’s Statement of Additional Information.
Expense Breakpoint Discounts [Text]	<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]	$ 25,000
Other Expenses, New Fund, Based on Estimates [Text]	<span style="color:#262626;font-family:Arial;font-size:8pt;">“Other Expenses” are based on estimated amounts for the current fiscal year. Actual expenses may differ from estimates.</span>
Shareholder Fees Caption [Optional Text]	<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 [Optional Text]	<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>
Expenses Deferred Charges [Text Block]	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 Example [Heading]	<span style="color:#0064FA;font-family:Arial;font-size:9pt;font-weight:bold;">Example</span>
Expense Example Narrative [Text Block]	The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other 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, that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The example also assumes that the contractual fee waiver and/or expense reimbursement is only in effect through October 31, 2026. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Portfolio Turnover [Heading]	<span style="color:#0064FA;font-family:Arial;font-size:10pt;font-weight:bold;">Portfolio Turnover</span>
Portfolio Turnover [Text Block]	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 example, affect the Fund's performance. No portfolio turnover rate is included for the Fund because the Fund has not yet commenced operations.