Business Segment Information (Reconciliation of Operating Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Operating income (loss)	$ 637.2	$ 459.8	$ 1,304.1	$ 1,111.8
Business and asset actions	(57.0)	(185.6)	(57.0)	(185.6)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Business and asset actions	(57.0)	(185.6)	(57.0)	(185.6)
Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	$ 694.2	$ 645.4	$ 1,361.1	$ 1,297.4