Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
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	$ 23.2	$ 39.8	$ 44.7
Interest cost	189.8	102.8	94.1
Expected return on plan assets	(176.3)	(235.7)	(277.9)
Prior service cost amortization	1.9	1.3	1.2
Actuarial loss amortization	71.3	80.7	97.8
Settlements	2.0	6.2	1.8
Curtailments	(1.9)	0.0	0.0
Other	0.9	1.3	1.0
Net Periodic Cost (Benefit)	110.9	(3.6)	(37.3)
Defined Benefit Pension Plan | U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	10.9	18.3	21.3
Interest cost	129.9	73.9	68.9
Expected return on plan assets	(127.1)	(168.3)	(194.5)
Prior service cost amortization	1.2	1.3	1.2
Actuarial loss amortization	59.7	66.0	78.5
Settlements	1.4	6.0	1.3
Curtailments	0.0	0.0	0.0
Other	0.0	0.0	0.0
Net Periodic Cost (Benefit)	76.0	(2.8)	(23.3)
Defined Benefit Pension Plan | International
Defined Benefit Plan Disclosure [Line Items]
Service cost	12.3	21.5	23.4
Interest cost	59.9	28.9	25.2
Expected return on plan assets	(49.2)	(67.4)	(83.4)
Prior service cost amortization	0.7	0.0	0.0
Actuarial loss amortization	11.6	14.7	19.3
Settlements	0.6	0.2	0.5
Curtailments	(1.9)	0.0	0.0
Other	0.9	1.3	1.0
Net Periodic Cost (Benefit)	$ 34.9	$ (0.8)	$ (14.0)