Class I [Member] Annual Fund Operating Expenses - Class I - AMG Yacktman Fund - Class I	Dec. 31, 2025
Prospectus [Line Items]
Management Fees (as a percentage of Assets)	0.43%
Distribution and Service (12b-1) Fees	0.00%
Other Expenses (as a percentage of Assets):	0.27%
Expenses (as a percentage of Assets)	0.70%

- References

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

+ Details

Name:	oef_DistributionAndService12b1FeesOverAssets
Namespace Prefix:	oef_
Data Type:	oef:nonNegativePure4ItemType
Balance Type:	na
Period Type:	duration

- References

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

+ Details

Name:	oef_ExpensesOverAssets
Namespace Prefix:	oef_
Data Type:	oef:nonNegativePure4ItemType
Balance Type:	na
Period Type:	duration

- References

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

+ Details

Name:	oef_ManagementFeesOverAssets
Namespace Prefix:	oef_
Data Type:	oef:nonNegativePure4ItemType
Balance Type:	na
Period Type:	duration

- References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 3
-Subsection instruction
-Paragraph 3
-Subparagraph c
-Sentence i

+ Details

Name:	oef_OtherExpensesOverAssets
Namespace Prefix:	oef_
Data Type:	oef:nonNegativePure4ItemType
Balance Type:	na
Period Type:	duration

- References

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

+ Details

Name:	oef_ProspectusLineItems
Namespace Prefix:	oef_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Details

Name:	dei_LegalEntityAxis=af_S000037566Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	oef_ClassAxis=af_C000115981Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: