Business Segment and Geographic Information (Reconciliation of Operating Income) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Sep. 30, 2022	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Facility closure		$ (23.2)		$ 0.0	$ (23.2)	$ 0.0
Business and asset actions	$ (73.7)			(73.7)	0.0	0.0
Gain on exchange with joint venture partner				0.0	36.8	0.0
Company headquarters relocation income (expense)			$ 33.8	0.0	0.0	33.8
Operating income				2,338.8	2,281.4	2,237.6
Segment Reconciling Items
Segment Reporting Information [Line Items]
Facility closure				0.0	(23.2)	0.0
Business and asset actions				(73.7)	0.0	0.0
Gain on exchange with joint venture partner				0.0	36.8	0.0
Company headquarters relocation income (expense)				0.0	0.0	33.8
Segment Total
Segment Reporting Information [Line Items]
Operating income				$ 2,412.5	$ 2,267.8	$ 2,203.8