Financial Instruments and Risk Management (Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - Recurring fair value measurement - Level 2 - USD ($) $ in Millions	Dec. 31, 2019	Sep. 30, 2019
Derivative [Line Items]
Deferred compensation	$ (40.1)	$ (40.6)
Derivatives - foreign currency contracts	0.1	2.1
Net liabilities at estimated fair value	$ (40.0)	$ (38.5)

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

Name:	us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant