Shareholder Fees	Mar. 01, 2021 USD ($)
Class Z Shares \| Alger Mid Cap Focus Fund - I \| Class Z
Shareholder Fees:
Shareholder Fees (fees paid directly from your investment)	none

Other Expenses

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection table
-Paragraph 1
-Subparagraph 10

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Namespace Prefix:	rr_
Data Type:	rr:NonNegativeMonetaryType
Balance Type:	na
Period Type:	duration