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Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Effective tax rate (percent)	18.60%	16.30%	18.10%	18.60%
Income tax payments, net of refunds			$ 341.3	$ 284.8
Cash provided by discontinued operations, tax settlement refund			$ 0.0	$ 6.7
Continuing operations
Income Tax [Line Items]
Tax benefit related to release of uncertain tax positions		$ 21.5
Discontinued operations \| EfW
Income Tax [Line Items]
Tax benefit related to release of uncertain tax positions		$ 8.2