New Accounting Guidance (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Oct. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 406.5
Operating lease right-of-use assets	376.8
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities				$ 375.3
Operating lease right-of-use assets				$ 332.3
Accounting Standards Update 2017-12 | Other Nonoperating Income (Expense)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excluded components recognized within earnings	$ 33.5
Accounting Standards Update 2017-12 | Interest Expense
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excluded components recognized within earnings		$ 33.3	$ 42.6