Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 20.7	$ 20.9	$ 23.2
Interest cost	176.5	194.9	189.8
Expected return on plan assets	(192.6)	(167.4)	(176.3)
Prior service cost amortization	2.1	2.0	1.9
Actuarial loss amortization	56.5	70.2	71.3
Settlements	1.3	2.3	2.0
Curtailments	1.2	0.0	(1.9)
Other	0.3	0.9	0.9
Net Periodic Cost	66.0	123.8	110.9
U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	9.1	9.6	10.9
Interest cost	119.5	134.9	129.9
Expected return on plan assets	(132.6)	(120.1)	(127.1)
Prior service cost amortization	1.1	1.1	1.2
Actuarial loss amortization	46.8	57.3	59.7
Settlements	0.8	1.1	1.4
Curtailments	1.2	0.0	0.0
Other	0.0	0.0	0.0
Net Periodic Cost	45.9	83.9	76.0
International
Defined Benefit Plan Disclosure [Line Items]
Service cost	11.6	11.3	12.3
Interest cost	57.0	60.0	59.9
Expected return on plan assets	(60.0)	(47.3)	(49.2)
Prior service cost amortization	1.0	0.9	0.7
Actuarial loss amortization	9.7	12.9	11.6
Settlements	0.5	1.2	0.6
Curtailments	0.0	0.0	(1.9)
Other	0.3	0.9	0.9
Net Periodic Cost	$ 20.1	$ 39.9	$ 34.9