XML 65 R51.htm IDEA: XBRL DOCUMENT
v3.3.0.814

Affiliate Equity (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2015 | Sep. 30, 2014 | Dec. 31, 2014
Affiliate Equity [Abstract] |  |  |  |  |
Compensation expenses related to affiliate equity attributable to noncontrolling interest | $ 5.9 | $ 7.9 | $ 49.0 | $ 35.1 |
Affiliate equity compensation cost not yet recognized | 78.6 |  | $ 78.6 |  | $ 71.1
Period for recognition (in years) |  |  | 4 years |  |
Affiliate equity compensation cost not yet recognized attributable to noncontrolling interest | $ 54.3 |  | $ 54.3 |  | $ 41.6

X
- Definition Affiliate Equity [Abstract] + References No definition available. + Details
Name: | amg_AffiliateEquityAbstract
Namespace Prefix: | amg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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 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