Business Segment and Geographic Information (Reconciliation of Segment Operating Income to Consolidated Results) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Operating income	$ (877.0)	$ 4,466.1	$ 2,494.6
Business and asset actions	(3,747.0)	(57.0)	(244.6)
Shareholder activism-related costs	(86.3)	0.0	0.0
Gain on sale of business	67.3	1,575.6	0.0
Equity affiliates' income	647.7	647.7	604.3
Interest expense	214.0	218.8	177.5
Other non-operating income (expense), net	2.6	(73.8)	(39.0)
Income (Loss) From Continuing Operations Before Taxes	(440.7)	4,821.2	2,882.4
Project exit-related impairment of equity method investment	6.8	0.0	0.0
Segment Reconciling Items
Segment Reporting Information [Line Items]
Business and asset actions	(3,747.0)	(57.0)	(244.6)
Shareholder activism-related costs	(86.3)	0.0	0.0
Gain on sale of business	67.3	1,575.6	0.0
Gain on sale of other assets	31.3	0.0	0.0
Project exit-related impairment of equity method investment	6.8
Segment Total
Segment Reporting Information [Line Items]
Operating income	2,857.7	2,947.5	2,739.2
Equity affiliates' income	$ 654.5	$ 647.7	$ 604.3