XML 75 R96.htm IDEA: XBRL DOCUMENT v2.4.0.8

Affiliate Equity Summary of affiliate equity compensation expense (Details) (Affiliated Entity [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Affiliated Entity [Member]
Affiliate Equity [Line Items]
Tax Benefit	$ 21.7	$ 17.0	$ 12.0
Affiliate Equity Compensation Expense	$ 72.3	$ 60.4	$ 38.1

X

- Definition

Affiliate Equity Compensation Expense, Including Portion Attributable to Noncontrolling Interest

+ References

No definition available.

+ Details

Name:	amg_AffiliateEquityCompensationExpenseIncludingPortionAttributabletoNoncontrollingInterest
Namespace Prefix:	amg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Affiliate Equity Compensation Expense, Tax Benefit (Expense)

+ References

No definition available.

+ Details

Name:	amg_AffiliateEquityCompensationExpenseTaxBenefitExpense
Namespace Prefix:	amg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	amg_AffiliateEquityLineItems
Namespace Prefix:	amg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration