Alger Health Sciences Fund Shareholder Fees - Class A C Shares [Member] - Alger Health Sciences Fund	Oct. 31, 2025
Class A
Prospectus [Line Items]
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)	5.25%
Maximum Deferred Sales Charge (as a percentage of Offering Price)	0.00%	[1]
Class C
Prospectus [Line Items]
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)	0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price)	1.00%

[1] 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.