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Earnings Per Share - Schedule of Shares Excluded from Calculation of Basic and Diluted Earnings Per Share (Details)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Stock Options And Restricted Stock    
Antidilutive Securities Excluded from Computation of Earnings Per Share    
Antidilutive securities excluded from computation of earnings per share, amount 0.1us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= amg_EmployeeStockOptionsandRestrictedStockMember
0.3us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= amg_EmployeeStockOptionsandRestrictedStockMember
Junior Convertible Trust Preferred Securities    
Antidilutive Securities Excluded from Computation of Earnings Per Share    
Antidilutive securities excluded from computation of earnings per share, amount 0us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= amg_JuniorConvertibleTrustPreferredSecuritiesMember
3.7us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= amg_JuniorConvertibleTrustPreferredSecuritiesMember