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Redeemable Non-Controlling Interests (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Redeemable Non-controlling Interests
Balance, beginning of period		$ 811.9	[1]	$ 673.5
Changes attributable to Affiliate sponsored consolidated products		51.6		12.4
Transfers to Other liabilities		(105.4)		(192.3)
Transfers from Non-controlling interests		44.8		76.8
Changes in redemption value		30.8		241.5		$ 71.4
Balance, end of period		833.7	[1]	811.9	[1]	$ 673.5
Affiliate sponsored investment products
Redeemable Non-controlling Interests
Balance, beginning of period	[1]	39.4
Balance, end of period	[1]	$ 91.0		$ 39.4
Minimum
Noncontrolling Interest [Line Items]
Term of conditional right put interest		5 years
Maximum
Noncontrolling Interest [Line Items]
Term of conditional right put interest		15 years
[1] As of December 31, 2017 and 2018, Redeemable non-controlling interests include Affiliate sponsored consolidated products primarily attributable to third-party investors of $39.4 million and $91.0 million, respectively.

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Increase (decrease) in redeemable non-controlling interests during the period as a result of a change in the redemption value.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The cash outflow during the period for redemption of redeemable noncontrolling interests.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

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As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 480
-SubTopic 10
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-Paragraph 3A
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