XML 111 R85.htm IDEA: XBRL DOCUMENT v2.4.1.9

Fixed Assets and Lease Commitments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fixed Assets and Lease Commitments [Abstract]
Consolidated rent expense	$ 30.5us-gaap_OperatingLeasesRentExpenseNet	$ 30.3us-gaap_OperatingLeasesRentExpenseNet	$ 30.5us-gaap_OperatingLeasesRentExpenseNet

X

- Details

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

X

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration