S000041917 [Member] Expense Example - AMG Boston Common Global Impact Fund - Class I	Sep. 30, 2025 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 95
Expense Example, with Redemption, 3 Years	301
Expense Example, with Redemption, 5 Years	524
Expense Example, with Redemption, 10 Years	$ 1,165

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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