New Accounting Guidance - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2021	Oct. 01, 2020	Sep. 30, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables	$ 1,428.2		$ 1,233.1
Deferred tax liabilities	311.7		305.3
Retained earnings	$ 11,550.8		$ 10,472.6
ASU 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables		$ 4.1
Deferred tax liabilities		0.8
Retained earnings		$ 3.3