Consolidated Investment Products - Schedule of Redeemable Noncontrolling Interest of CSIPs (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Oct. 01, 2016
Temporary Equity [Line Items]
Balance at beginning of period	$ 1,941.9	$ 61.1
Net income (loss)	11.5	(23.5)
Net subscriptions (distributions) and other	7.0	12.3
Net deconsolidations	(0.3)
Balance at End of Period	2,208.1	841.2
Redeemable noncontrolling interests [Member]
Temporary Equity [Line Items]
Net subscriptions (distributions) and other	254.7	(13.6)
Net deconsolidations	$ 0.0	$ (7.5)
ASU 2015-02 [Member]
Temporary Equity [Line Items]
Adoption of new accounting guidance			$ (325.9)
ASU 2015-02 [Member] \| Redeemable noncontrolling interests [Member]
Temporary Equity [Line Items]
Adoption of new accounting guidance			$ 824.7

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- Definition

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

+ References

No definition available.

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Net Increase or Decrease in balance of noncontrolling interest in the subsidiary during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=68079674&loc=SL4568740-111683

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Amount of Net Income (Loss) attributable to redeemable noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.19)
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- Definition

Carrying amount, attributable to parent and noncontrolling interests, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.27(b))
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- Definition

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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