XML 49 R37.htm IDEA: XBRL DOCUMENT
v3.4.0.3

Fair Value Measurements - Schedule of Quantitative Information used in Valuing Level 3 Liabilities (Details) - Discounted Cash Flow - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2016 | Dec. 31, 2015
Contingent Payment Arrangements |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Fair value Liabilities | $ 7.8 | $ 10.2
Discount rate (as a percent) |  | 15.00%
Contingent Payment Arrangements | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rate (as a percent) | 4.00% | 3.00%
Discount rate (as a percent) | 14.00% |
Contingent Payment Arrangements | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rate (as a percent) | 8.00% | 8.00%
Discount rate (as a percent) | 15.00% |
Affiliate Equity Obligations |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Fair value Liabilities | $ 35.6 | $ 62.3
Affiliate Equity Obligations | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rate (as a percent) | (1.00%) | 1.00%
Discount rate (as a percent) | 15.00% | 14.00%
Affiliate Equity Obligations | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rate (as a percent) | 11.00% | 9.00%
Discount rate (as a percent) | 16.00% | 15.00%

X
- Definition Represents percentage of assumed growth rates, used as an input to measure fair value. + References No definition available. + Details
Name: | amg_FairValueInputsGrowthRates
Namespace Prefix: | amg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueInputsDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
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_FairValueInputsLiabilitiesQuantitativeInformationLineItems
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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=amg_DiscountedCashFlowValuationTechniqueMember
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_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
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: |