Alger Small Cap Focus Fund Expense Example - Class Y Shares [Member] - Alger Small Cap Focus Fund - Class Y	Oct. 31, 2025 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 88
Expense Example, with Redemption, 3 Years	277
Expense Example, with Redemption, 5 Years	484
Expense Example, with Redemption, 10 Years	$ 1,081

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