Goodwill and Acquired Client Relationships - Schedule of Changes in Goodwill (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Changes in goodwill
Balance at the beginning of the period	$ 2,341.7us-gaap_Goodwill	$ 2,355.2us-gaap_Goodwill
Goodwill acquired	344.5us-gaap_GoodwillAcquiredDuringPeriod	0us-gaap_GoodwillAcquiredDuringPeriod
Foreign currency translation	(33.4)us-gaap_GoodwillTranslationAdjustments	(13.5)us-gaap_GoodwillTranslationAdjustments
Balance at the end of the period	2,652.8us-gaap_Goodwill	2,341.7us-gaap_Goodwill
Institutional
Changes in goodwill
Balance at the beginning of the period	1,076.3	1,078.5
Goodwill acquired	97.2	0
Foreign currency translation	(14.4)	(2.2)
Balance at the end of the period	1,159.1	1,076.3
Mutual Fund
Changes in goodwill
Balance at the beginning of the period	928.1	939.5
Goodwill acquired	208.1	0
Foreign currency translation	(10.9)	(11.4)
Balance at the end of the period	1,125.3	928.1
High Net Worth
Changes in goodwill
Balance at the beginning of the period	337.3	337.2
Goodwill acquired	39.2	0
Foreign currency translation	(8.1)	0.1
Balance at the end of the period	$ 368.4	$ 337.3

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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