Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4.5	$ 5.0	$ 9.4	$ 10.2
Interest cost	44.1	43.7	87.7	87.5
Expected return on plan assets	(52.5)	(47.7)	(104.7)	(95.6)
Prior service cost amortization	0.5	0.5	1.1	1.0
Actuarial loss amortization	11.2	14.1	22.6	28.2
Settlements	1.3	0.1	1.3	0.1
Other	0.3	0.0	0.6	0.1
Net Periodic Cost	9.4	15.7	$ 18.0	$ 31.5
Non-service Net Periodic Cost, location			Other non-operating income (expense), net	Other non-operating income (expense), net
U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.9	2.3	$ 3.8	$ 4.6
Interest cost	29.1	29.9	58.1	59.8
Expected return on plan assets	(35.3)	(33.2)	(70.5)	(66.4)
Prior service cost amortization	0.3	0.3	0.6	0.6
Actuarial loss amortization	8.5	11.7	17.4	23.4
Settlements	1.2	0.0	1.2	0.0
Other	0.0	0.0	0.0	0.0
Net Periodic Cost	5.7	11.0	10.6	22.0
International
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.6	2.7	5.6	5.6
Interest cost	15.0	13.8	29.6	27.7
Expected return on plan assets	(17.2)	(14.5)	(34.2)	(29.2)
Prior service cost amortization	0.2	0.2	0.5	0.4
Actuarial loss amortization	2.7	2.4	5.2	4.8
Settlements	0.1	0.1	0.1	0.1
Other	0.3	0.0	0.6	0.1
Net Periodic Cost	$ 3.7	$ 4.7	$ 7.4	$ 9.5