XML 21 R1.htm IDEA: XBRL DOCUMENT v3.21.2
Label Element Value
Risk Return Abstract rr_RiskReturnAbstract  
Document Type dei_DocumentType 485BPOS
Period End Date dei_DocumentPeriodEndDate Oct. 31, 2020
Registrant Name dei_EntityRegistrantName THE ALGER FUNDS
CIK dei_EntityCentralIndexKey 0000003521
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jul. 28, 2021
Effective Date dei_DocumentEffectiveDate Jul. 28, 2021
Prospectus Date rr_ProspectusDate Jul. 28, 2021
Entity Inv Company Type dei_EntityInvCompanyType N-1A
Alger Mid Cap Focus Fund - AC | Class A  
Risk Return Abstract rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol ALOAX
Alger Mid Cap Focus Fund - AC | Class C  
Risk Return Abstract rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol ALOCX
Alger Mid Cap Focus Fund - AC | Class Z  
Risk Return Abstract rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol AFOZX