Retirement Benefits (Components Recognized in Accumulated Other Comprehensive Income on Pretax Basis) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
U.S.
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 871.8	$ 680.4
Prior service cost (credit)	6.6	6.6
Net transition liability	0.0	0.0
Total	878.4	687.0
International
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	594.0	443.6
Prior service cost (credit)	3.6	(1.1)
Net transition liability	0.4	0.4
Total	$ 598.0	$ 442.9

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

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-Publisher FASB
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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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Amount, before tax, of accumulated other comprehensive income (loss) for transition asset (obligation) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 220
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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