Alger Health Sciences Fund Expense Example, No Redemption - Class A C Shares [Member] - Alger Health Sciences Fund - Class C	Oct. 31, 2025 USD ($)
Prospectus [Line Items]
Expense Example, No Redemption, 1 Year	$ 199
Expense Example, No Redemption, 3 Years	615
Expense Example, No Redemption, 5 Years	1,057
Expense Example, No Redemption, 10 Years	$ 2,285