Basis of Presentation and Accounting Policies - Recently Issued Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	Oct. 01, 2019	Sep. 30, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 342.9
Total operating lease liabilities		$ 364.4
Accounting Standards Update [Extensible List]	us-gaap:AcountingStandardsUpdate201601Member
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 316.0
Total operating lease liabilities	$ 329.0
Accounting Standards Update 2018-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201807Member
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