Restructuring and Other Costs - Schedule of Acquisition, Divestiture and Integration Costs (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Restructuring Cost And Reserve [Line Items]
Acquisition costs	$ 0.2	$ 28.2	$ 38.2
Integration costs	18.7	34.3	22.0
Divestiture costs	0.1	0.2	0.3
Other total	19.0	62.7	65.9
Other Segments [Member]
Restructuring Cost And Reserve [Line Items]
Acquisition costs	0.2	28.2	38.2
Integration costs	18.7	34.3	27.4
Divestiture costs	0.1	0.2	0.3
Other total	$ 19.0	$ 62.7	$ 65.9

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e1043-128460

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration