XML 82 R62.htm IDEA: XBRL DOCUMENT v3.24.0.1

Fair Value Measurements - Quantitative Information used in Valuing Level 3 Liabilities (Details) - Level 3 $ in Millions	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Contingent Payment Obligations | Monte Carlo simulation
Quantitative information for Level 3 Fair Value Measurements Liabilities
Fair Value	$ 14.7	$ 21.0
Contingent Payment Obligations | Monte Carlo simulation | Volatility | Minimum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.19	0.18
Contingent Payment Obligations | Monte Carlo simulation | Volatility | Maximum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.25	0.25
Contingent Payment Obligations | Monte Carlo simulation | Volatility | Weighted Average
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.21	0.18
Contingent Payment Obligations | Monte Carlo simulation | Discount rates | Minimum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.06	0.06
Contingent Payment Obligations | Monte Carlo simulation | Discount rates | Weighted Average
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.06	0.06
Affiliate equity purchase obligations | Discounted cash flow
Quantitative information for Level 3 Fair Value Measurements Liabilities
Fair Value	$ 53.9	$ 24.5
Affiliate equity purchase obligations | Discounted cash flow | Discount rates | Minimum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.14	0.14
Affiliate equity purchase obligations | Discounted cash flow | Discount rates | Maximum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.17	0.17
Affiliate equity purchase obligations | Discounted cash flow | Discount rates | Weighted Average
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.14	0.14
Affiliate equity purchase obligations | Discounted cash flow | Growth rates | Minimum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	(0.06)	(0.03)
Affiliate equity purchase obligations | Discounted cash flow | Growth rates | Maximum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.07	0.06
Affiliate equity purchase obligations | Discounted cash flow | Growth rates | Weighted Average
Quantitative information for Level 3 Fair Value Measurements Liabilities
Obligations to related parties, measurement input	0.01	0.01

X

- Definition

Obligations to Related Parties, Measurement Input

+ References

No definition available.

+ Details

Name:	amg_ObligationstoRelatedPartiesMeasurementInput
Namespace Prefix:	amg_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

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

X

- Definition

Fair value of financial and nonfinancial obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=amg_ContingentPaymentArrangementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ValuationTechniqueAxis=amg_ValuationTechniqueMonteCarloSimulationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=amg_ObligationsToRelatedPartiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_ValuationTechniqueDiscountedCashFlowMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputLongTermRevenueGrowthRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: