Goodwill and Other Intangible Assets - Schedule of Definite-Lived Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 1,477.1	$ 1,476.2
Accumulated Amortization	(294.7)	(62.8)
Total	1,182.4	1,413.4
Management contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,232.0	1,231.2
Accumulated Amortization	(262.6)	(57.6)
Total	969.4	1,173.6
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	230.7	230.6
Accumulated Amortization	(28.0)	(4.0)
Total	202.7	226.6
Developed software [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	14.4	14.4
Accumulated Amortization	(4.1)	(1.2)
Total	$ 10.3	$ 13.2

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 928
-SubTopic 340
-Section 50
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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 926
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