Retirement Benefits (Change in Plan Assets) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contributions	$ 68.3
U.S.
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	2,869.2	$ 2,705.3
Actual return on plan assets	150.2	319.6
Company contributions	14.6	27.2
Participant contributions	0.0	0.0
Divestitures	0.0	0.0
Benefits paid	(157.3)	(182.9)
Settlements	(191.8)	0.0
Currency translation/other	0.0	0.0
Fair value at end of year	2,684.9	2,869.2
Funded status at end of year	(237.9)	(488.5)
International
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	1,540.0	1,411.1
Actual return on plan assets	115.5	87.9
Company contributions	53.7	42.2
Participant contributions	1.4	1.4
Divestitures	0.0	(3.0)
Benefits paid	(51.3)	(46.5)
Settlements	(24.6)	(5.3)
Currency translation/other	(46.5)	52.2
Fair value at end of year	1,588.2	1,540.0
Funded status at end of year	$ (72.3)	$ (209.5)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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- Definition

Amount of decrease in plan assets of defined benefit plan from disposal or classification as held-for-sale.

+ References

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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- Definition

Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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- Definition

Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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- Definition

Amount of contributions received by defined benefit plan from participant which increases plan assets.

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan.

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- Definition

Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract.

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