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v3.25.3

Equity Distribution Program (Details) $ in Millions | Mar. 31, 2025 USD ($)
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Forward Equity Sale Agreements [Abstract] |
Equity distribution program, maximum amount authorized | $ 500.0

X
- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
Name: | amg_ForwardEquitySaleAgreementsAbstract
Namespace Prefix: | amg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Stock Issuable, Value, Maximum + References No definition available. + Details
Name: | amg_StockIssuableValueMaximum
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant