Basis of Presentation and Accounting Policies - Recently Issued Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	Oct. 01, 2019	Sep. 30, 2021	Sep. 30, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 377.7	$ 342.9
Total lease liabilities		$ 403.5
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 316.0
Total lease liabilities	329.0
Accumulated other comprehensive loss | Accounting Standards Update 2018-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of tax effects from accumulated other comprehensive loss into retained earnings	$ 147.0