Retirement Benefits (Benefit Liability Exceeds Value of Plan Assets) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
U.S.
Pension Plans with PBO in Excess of Plan Assets:
PBO	$ 3,069.2	$ 2,733.6
Fair value of Plan assets	2,602.8	2,467.5
Pension Plans with ABO in Excess of Plan Assets:
ABO	2,941.2	2,608.6
Fair value of plan assets	2,602.8	2,467.5
International
Pension Plans with PBO in Excess of Plan Assets:
PBO	521.1	452.6
Fair value of Plan assets	318.0	276.8
Pension Plans with ABO in Excess of Plan Assets:
ABO	413.3	357.9
Fair value of plan assets	$ 266.5	$ 228.2

Amount of plan asset for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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Amount of projected benefit obligation for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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