Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5.3	$ 5.2	$ 15.5	$ 15.6
Interest cost	44.4	48.6	131.9	145.8
Expected return on plan assets	(48.4)	(41.7)	(144.0)	(125.2)
Prior service cost amortization	0.5	0.5	1.5	1.6
Actuarial loss amortization	14.1	17.5	42.3	52.5
Settlements	0.3	0.4	0.4	0.6
Other	0.1	0.6	0.2	0.8
Net Periodic Cost	16.3	31.1	47.8	91.7
U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.3	2.4	6.9	7.2
Interest cost	29.9	33.7	89.7	101.1
Expected return on plan assets	(33.1)	(30.0)	(99.5)	(90.0)
Prior service cost amortization	0.2	0.3	0.8	0.9
Actuarial loss amortization	11.7	14.3	35.1	42.9
Settlements	0.0	0.0	0.0	0.0
Other	0.0	0.0	0.0	0.0
Net Periodic Cost	11.0	20.7	33.0	62.1
International
Defined Benefit Plan Disclosure [Line Items]
Service cost	3.0	2.8	8.6	8.4
Interest cost	14.5	14.9	42.2	44.7
Expected return on plan assets	(15.3)	(11.7)	(44.5)	(35.2)
Prior service cost amortization	0.3	0.2	0.7	0.7
Actuarial loss amortization	2.4	3.2	7.2	9.6
Settlements	0.3	0.4	0.4	0.6
Other	0.1	0.6	0.2	0.8
Net Periodic Cost	$ 5.3	$ 10.4	$ 14.8	$ 29.6