Investments - Schedule of Investment Components (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Investment Holdings [Line Items]
Investments at fair value	$ 114.7	$ 303.8
Equity-accounted investments in Affiliates and consolidated Funds	103.7	73.1
Total investments per Condensed Consolidated Balance Sheets	218.4	376.9
Investments held for sale	139.9	0.0
Total investments and investments held for sale per Condensed Consolidated Balance Sheets	358.3	376.9
Consolidated Funds
Investment Holdings [Line Items]
Investments at fair value	0.0	119.5
Total investments per Condensed Consolidated Balance Sheets	101.9	190.6
Investments held for sale	112.9	0.0
Consolidated Entity Excluding Consolidated Funds
Investment Holdings [Line Items]
Investments at fair value	114.7	184.3
Total investments per Condensed Consolidated Balance Sheets	116.5	186.3
Investments held for sale	27.0	0.0
Other investments held at fair value \| Consolidated Entity Excluding Consolidated Funds
Investment Holdings [Line Items]
Investments at fair value	48.6	95.5
Investments related to long-term incentive compensation plans held at fair value \| Consolidated Entity Excluding Consolidated Funds
Investment Holdings [Line Items]
Investments at fair value	$ 66.1	$ 88.8

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Equity-Accounted Investments In Affiliates And Consolidated Funds

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Sum of the carrying amounts as of the balance sheet date of all investments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(h))
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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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