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Affiliate Equity (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended |
--- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014
Affiliate Equity [Abstract] |  |  |
Compensation expenses related to affiliate equity noncontrolling interests | $ 5.3 amg_CompensationExpensesRelatedtoAffiliateEquityAttributabletoNoncontrollingInterest | $ 7.2 amg_CompensationExpensesRelatedtoAffiliateEquityAttributabletoNoncontrollingInterest |
Affiliate equity compensation cost not yet recognized | 77.9 amg_AffiliateEquityCompensationCostNotyetRecognized |  | 71.1 amg_AffiliateEquityCompensationCostNotyetRecognized
Period for recognition | 4 years |  |
Affiliate equity compensation cost not yet recognized attributable to noncontrolling interest | $ 50.5 amg_AffiliateEquityCompensationCostNotyetRecognizedAttributabletoNoncontrollingInterest |  | $ 41.6 amg_AffiliateEquityCompensationCostNotyetRecognizedAttributabletoNoncontrollingInterest

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- Details
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