Alger Health Sciences Fund Expense Example - Class Z Shares [Member] - Alger Health Sciences Fund - Class Z	Oct. 31, 2025 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 78
Expense Example, with Redemption, 3 Years	252
Expense Example, with Redemption, 5 Years	445
Expense Example, with Redemption, 10 Years	$ 1,004

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