XML 62 R49.htm IDEA: XBRL DOCUMENT
v3.20.2

Commitments and Contingencies (Details) - USD ($) | 3 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Sep. 30, 2020
Affiliate |  |
Commitments and Contingencies |  |
Co-investment commitments in partnership |  | $ 129,400,000
Equity Method Investee |  |
Commitments and Contingencies |  |
Noncontrolling interest, sell of ownership percentage | 5.00% |
Minority Owner | Equity Method Investee |  |
Commitments and Contingencies |  |
Ownership percentage by minority owner |  | 14.00%
Payments for Investment in Affiliate |  |
Commitments and Contingencies |  |
Contingent payments in 2020 |  | $ 35,000,000.0
Contingent payments in 2021 |  | 35,000,000.0
Contingent payments in 2022 |  | 37,500,000
Payments for Achievement of Financial Targets |  |
Commitments and Contingencies |  |
Contingent payments in 2021 |  | 150,000,000.0
Contingent payments in 2022 |  | 77,500,000
Contingent payments from 2023 through 2025 |  | 62,500,000
Expected payments |  | 53,000,000
Expected payments, remainder of fiscal year |  | 0
Payment contingent on not meeting financial targets (up to) |  | 12,500,000
Payment contingent on exercise of option to reduce ownership percentage |  | $ 25,000,000.0

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

X
- Definition The amount that the entity agreed to co-invest in certain investment partnerships where the entity serves as the general partner. + References No definition available. + Details
Name: | amg_InvestmentCommitmentAmount
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Noncontrolling Interest, Notification of Possible Sale of Noncontrolling Interest, Percentage + References No definition available. + Details
Name: | amg_NoncontrollingInterestNotificationofPossibleSaleofNoncontrollingInterestPercentage
Namespace Prefix: | amg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Other Commitment, Contingent Consideration, Asset + References No definition available. + Details
Name: | amg_OtherCommitmentContingentConsiderationAsset
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Other Commitment, Contingent Consideration, Option To Reduce Ownership Interest, Asset + References No definition available. + Details
Name: | amg_OtherCommitmentContingentConsiderationOptionToReduceOwnershipInterestAsset
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Other Commitment, Due In Third, Fourth, And Fifth Year + References No definition available. + Details
Name: | amg_OtherCommitmentDueInThirdFourthAndFifthYear
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Other Commitment Expected Payments + References No definition available. + Details
Name: | amg_OtherCommitmentExpectedPayments
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Other Commitment, Expected Payments, Remainder Of Fiscal Year + References No definition available. + Details
Name: | amg_OtherCommitmentExpectedPaymentsRemainderOfFiscalYear
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of commitment classified as other to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References No definition available. + Details
Name: | us-gaap_OtherCommitmentDueInNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of commitment classified as other to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References No definition available. + Details
Name: | us-gaap_OtherCommitmentDueInSecondYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of commitment classified as other to be paid in remainder of current fiscal year. + References No definition available. + Details
Name: | us-gaap_OtherCommitmentsFutureMinimumPaymentsRemainderOfFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ConsolidatedEntitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_EquityMethodInvesteeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=amg_MinorityOwnerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_OtherCommitmentsAxis=amg_PaymentsForInvestmentInAffiliateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_OtherCommitmentsAxis=amg_PaymentsForAchievementOfFinancialTargetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |