Document and Entity Information	Total
Prospectus:
Document Type	497
Document Period End Date	May 31, 2016
Registrant Name	ALGER FUNDS
Central Index Key	0000003521
Amendment Flag	false
Document Creation Date	May 31, 2016
Document Effective Date	Jun. 01, 2016
Prospectus Date	Mar. 01, 2016
Class A, B, and C Prospectus \| Alger Capital Appreciation Fund \| Alger Capital Appreciation Fund Class A
Prospectus:
Trading Symbol	ACAAX
Class A, B, and C Prospectus \| Alger Capital Appreciation Fund \| Alger Capital Appreciation Fund Class B
Prospectus:
Trading Symbol	ACAPX
Class A, B, and C Prospectus \| Alger Capital Appreciation Fund \| Alger Capital Appreciation Fund Class C
Prospectus:
Trading Symbol	ALCCX
Class A, B, and C Prospectus \| Alger Mid Cap Growth Fund \| Alger Mid Cap Growth Fund Class A
Prospectus:
Trading Symbol	AMGAX
Class A, B, and C Prospectus \| Alger Mid Cap Growth Fund \| Alger Mid Cap Growth Fund Class B
Prospectus:
Trading Symbol	AMCGX
Class A, B, and C Prospectus \| Alger Mid Cap Growth Fund \| Alger Mid Cap Growth Fund Class C
Prospectus:
Trading Symbol	AMGCX
Class Z Prospectus \| Alger Capital Appreciation Fund \| Alger Capital Appreciation Fund Class Z
Prospectus:
Trading Symbol	ACAZX
Class Z Prospectus \| Alger Mid Cap Growth Fund \| Alger Mid Cap Growth Fund Class Z
Prospectus:
Trading Symbol	AMCZX

If the value is true, then the document is an amendment to previously-filed/accepted document.

No definition available.

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

The date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

+ References

No definition available.

+ Details

Name:	dei_DocumentCreationDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.

+ References

No definition available.

+ Details

Name:	dei_DocumentEffectiveDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

+ References

No definition available.

+ Details

Name:	dei_DocumentPeriodEndDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word "Other".

+ References

No definition available.

+ Details

Name:	dei_DocumentType
Namespace Prefix:	dei_
Data Type:	dei:submissionTypeItemType
Balance Type:	na
Period Type:	duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

+ Details

Name:	dei_EntityCentralIndexKey
Namespace Prefix:	dei_
Data Type:	dei:centralIndexKeyItemType
Balance Type:	na
Period Type:	duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

+ Details

Name:	dei_EntityRegistrantName
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:	dei_TradingSymbol
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The date of the prospectus.

+ References

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

+ Details

Name:	rr_ProspectusDate
Namespace Prefix:	rr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Prospectus Table.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A

+ Details

Name:	rr_ProspectusTable
Namespace Prefix:	rr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_DocumentInformationDocumentAxis=ck0000003521_doc_Class_A_B_and_C_ProspectusMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ck0000003521_S000009163Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000024912Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000024913Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000024914Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ck0000003521_S000009162Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000024909Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000024910Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000024911Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_DocumentInformationDocumentAxis=ck0000003521_doc_Class_Z_ProspectusMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000095959Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=ck0000003521_C000156504Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: