Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense), Net	Other Nonoperating Income (Expense), Net	Other Nonoperating Income (Expense), Net
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 20.9	$ 23.2	$ 39.8
Interest cost	194.9	189.8	102.8
Expected return on plan assets	(167.4)	(176.3)	(235.7)
Prior service cost amortization	2.0	1.9	1.3
Actuarial loss amortization	70.2	71.3	80.7
Settlements	2.3	2.0	6.2
Curtailments	0.0	(1.9)	0.0
Other	0.9	0.9	1.3
Net Periodic Cost (Benefit)	123.8	110.9	(3.6)
Defined Benefit Pension Plan | U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	9.6	10.9	18.3
Interest cost	134.9	129.9	73.9
Expected return on plan assets	(120.1)	(127.1)	(168.3)
Prior service cost amortization	1.1	1.2	1.3
Actuarial loss amortization	57.3	59.7	66.0
Settlements	1.1	1.4	6.0
Curtailments	0.0	0.0	0.0
Other	0.0	0.0	0.0
Net Periodic Cost (Benefit)	83.9	76.0	(2.8)
Defined Benefit Pension Plan | International
Defined Benefit Plan Disclosure [Line Items]
Service cost	11.3	12.3	21.5
Interest cost	60.0	59.9	28.9
Expected return on plan assets	(47.3)	(49.2)	(67.4)
Prior service cost amortization	0.9	0.7	0.0
Actuarial loss amortization	12.9	11.6	14.7
Settlements	1.2	0.6	0.2
Curtailments	0.0	(1.9)	0.0
Other	0.9	0.9	1.3
Net Periodic Cost (Benefit)	$ 39.9	$ 34.9	$ (0.8)