Retirement Benefits (Change in Plan Assets) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contributions	$ 37.5
U.S.
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	2,832.4	$ 2,684.9
Actual return on plan assets	364.6	289.9
Company contributions	15.5	16.0
Participant contributions	0.0	0.0
Benefits paid	(152.5)	(146.2)
Settlements	(11.7)	(12.2)
Currency translation and other	0.0	0.0
Fair Value at End of Year	3,048.3	2,832.4
Funded Status at End of Year	(375.5)	(449.2)
International
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	1,672.4	1,588.2
Actual return on plan assets	(3.1)	208.0
Company contributions	22.0	24.2
Participant contributions	1.2	1.3
Benefits paid	(49.8)	(47.7)
Settlements	(0.9)	(1.6)
Currency translation and other	85.0	(100.0)
Fair Value at End of Year	1,726.8	1,672.4
Funded Status at End of Year	$ (222.9)	$ (191.6)