XML 89 R77.htm IDEA: XBRL DOCUMENT v3.25.1

Earnings Per Share - Schedule of Shares Excluded from Calculation of Basic and Diluted Earnings (Loss) Per Share (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Stock options and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0.3	0.4
Shares issuable to settle Redeemable non-controlling interests
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	2.9	0.5

X

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=amg_EmployeeStockOptionsandRestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=amg_SharesIssuableToSettleRedeemableNonControllingInterestsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: