Share-Based Compensation (Compensation Cost Recognized in Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Payment Arrangement, Additional Disclosure [Abstract]
Before-tax share-based compensation cost	$ 14.5	$ 10.7	$ 46.9	$ 38.0
Income tax benefit	(3.5)	(2.6)	(11.4)	(9.3)
After-tax share-based compensation cost	$ 11.0	$ 8.1	$ 35.5	$ 28.7