XML 96 R70.htm IDEA: XBRL DOCUMENT
v3.20.2

Income Taxes - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Income Tax Provision |  |  |  |
Effective income tax rate reconciliation, release of uncertain tax position | $ 5.5 |  | $ 5.5 |
Effective income tax rate reconciliation, prior year income taxes, amount | $ 4.1 |  | $ 4.1 |
Controlling Interest |  |  |  |
Income Tax Provision |  |  |  |
Effective tax rate | 3.40% | 23.70% | 7.60% | 25.30%

X
- Definition Effective Income Tax Rate Reconciliation, Capital Loss Benefit Carryback + References No definition available. + Details
Name: | amg_EffectiveIncomeTaxRateReconciliationCapitalLossBenefitCarryback
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Effective Income Tax Rate Reconciliation, Release Of Uncertain Tax Position + References No definition available. + Details
Name: | amg_EffectiveIncomeTaxRateReconciliationReleaseOfUncertainTaxPosition
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 + Details
Name: | us-gaap_EffectiveIncomeTaxRateContinuingOperations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |