Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
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 non-operating income (expense), net	Other non-operating income (expense), net
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5.2	$ 5.8	$ 10.4	$ 11.8
Interest cost	48.7	47.4	97.2	94.3
Expected return on plan assets	(41.9)	(44.0)	(83.5)	(87.6)
Prior service cost amortization	0.6	0.4	1.1	0.7
Actuarial loss amortization	17.5	18.0	35.0	35.8
Settlements	0.2	1.1	0.2	1.1
Curtailments			0.0	(1.9)
Other	0.1	0.2	0.2	0.5
Net Periodic Cost	30.4	28.9	60.6	54.7
U.S. | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.4	2.8	4.8	5.5
Interest cost	33.7	32.5	67.4	65.0
Expected return on plan assets	(30.0)	(31.8)	(60.0)	(63.6)
Prior service cost amortization	0.3	0.3	0.6	0.6
Actuarial loss amortization	14.3	15.0	28.6	29.8
Settlements	0.0	0.9	0.0	0.9
Curtailments			0.0	0.0
Other	0.0	0.0	0.0	0.0
Net Periodic Cost	20.7	19.7	41.4	38.2
International | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.8	3.0	5.6	6.3
Interest cost	15.0	14.9	29.8	29.3
Expected return on plan assets	(11.9)	(12.2)	(23.5)	(24.0)
Prior service cost amortization	0.3	0.1	0.5	0.1
Actuarial loss amortization	3.2	3.0	6.4	6.0
Settlements	0.2	0.2	0.2	0.2
Curtailments			0.0	(1.9)
Other	0.1	0.2	0.2	0.5
Net Periodic Cost	$ 9.7	$ 9.2	$ 19.2	$ 16.5