Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
U.S.
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 1.0	$ (6.2)	$ (1.5)	$ (18.4)
U.S. | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	4.6	5.3	13.8	16.0
Interest cost	18.4	17.2	55.2	51.7
Expected return on plan assets	(42.0)	(48.6)	(126.2)	(145.9)
Prior service cost amortization	0.3	0.3	0.9	0.9
Actuarial loss amortization	16.6	19.6	49.9	58.9
Settlements	3.1	0.0	4.9	0.0
Other	0.0	0.0	0.0	0.0
International
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	(0.4)	(3.3)	(0.4)	(10.6)
International | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	5.3	5.9	16.5	17.5
Interest cost	7.1	6.4	22.3	18.8
Expected return on plan assets	(16.6)	(21.2)	(51.9)	(62.4)
Prior service cost amortization	0.0	0.0	0.0	0.0
Actuarial loss amortization	3.6	4.8	11.3	14.2
Settlements	0.0	0.5	0.2	0.5
Other	$ 0.2	$ 0.3	$ 1.2	$ 0.8