XML 13 R54.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Affiliate Equity - Summary of Affiliate Equity Compensation (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2014 | Jun. 30, 2013 | Jun. 30, 2014 | Jun. 30, 2013 | Dec. 31, 2013
Affiliate Equity |  |  |  |  |
Affiliate equity expense | $ 30.7 | $ 12.3 | $ 45.9 | $ 23.8 |
Tax benefit | 4.3 | 2.4 | 7.2 | 5.6 |
Compensation expenses related to affiliate equity noncontrolling interests | 19.7 | 5.9 | 27.2 | 9.1 |
Affiliate equity compensation cost not yet recognized | 74.9 |  | 74.9 |  | 68.2
Affiliate equity compensation cost not yet recognized attributable to noncontrolling interest | $ 42.7 |  | $ 42.7 |  | $ 32.1
Period for recognition |  |  | 4 years |  |

X
- Definition Affiliate Equity, Compensation Cost Not yet Recognized + References No definition available. + Details
Name: | amg_AffiliateEquityCompensationCostNotyetRecognized
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Affiliate Equity, Compensation Cost Not yet Recognized Attributable to Noncontrolling Interest + References No definition available. + Details
Name: | amg_AffiliateEquityCompensationCostNotyetRecognizedAttributabletoNoncontrollingInterest
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Affiliate Equity, Compensation Cost Not yet Recognized, Period for Recognition + References No definition available. + Details
Name: | amg_AffiliateEquityCompensationCostNotyetRecognizedPeriodforRecognition
Namespace Prefix: | amg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Affiliate Equity Compensation, Tax Benefit from Compensation Expense + References No definition available. + Details
Name: | amg_AffiliateEquityCompensationTaxBenefitfromCompensationExpense
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | amg_AffiliateEquityDisclosureAbstract
Namespace Prefix: | amg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the compensation expenses related to Affiliate equity. + References No definition available. + Details
Name: | amg_CompensationExpensesRelatedToAffiliateEquity
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Compensation Expenses Related to Affiliate Equity Attributable to Noncontrolling Interest + References No definition available. + Details
Name: | amg_CompensationExpensesRelatedtoAffiliateEquityAttributabletoNoncontrollingInterest
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration