Retirement Benefits (Change in Plan Assets) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contributions	$ 32.6
U.S.
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	2,404.0	$ 3,343.7
Actual return on plan assets	61.4	(778.3)
Settlements	(4.7)	(19.2)
Company contributions	8.4	23.0
Participant contributions	0.0	0.0
Benefits paid	(170.1)	(165.2)
Currency translation and other	0.0	0.0
Fair Value at End of Year	2,299.0	2,404.0
Funded Status at End of Year	(49.8)	(46.8)
International
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	1,122.0	1,905.0
Actual return on plan assets	(52.7)	(498.5)
Settlements	(3.4)	(0.9)
Company contributions	24.2	21.7
Participant contributions	0.8	1.2
Benefits paid	(52.8)	(53.0)
Currency translation and other	95.9	(253.5)
Fair Value at End of Year	1,134.0	1,122.0
Funded Status at End of Year	$ (28.4)	$ (15.5)