Business Segment and Geographic Information (Schedule of Geographic Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 12,037.3	$ 12,100.6	$ 12,600.0
Plant and equipment, net	25,337.8	23,370.9	17,472.1
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	4,692.5	4,914.0	5,234.2
Plant and equipment, net	8,909.1	9,159.3	7,431.0
SAUDI ARABIA
Revenues from External Customers and Long-Lived Assets [Line Items]
Plant and equipment, net	6,910.6	5,080.2	1,818.1
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	1,933.5	1,951.5	1,988.1
Plant and equipment, net	2,654.6	3,845.7	3,744.7
Other foreign operations
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	5,411.3	5,235.1	5,377.7
Plant and equipment, net	$ 6,863.5	$ 5,285.7	$ 4,478.3