Retirement Benefits (Benefit Liability Exceeds Value of Plan Assets) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
U.S.
Pension Plans with PBO in Excess of Plan Assets:
PBO	$ 2,733.6	$ 3,116.7
Fair value of Plan assets	2,467.5	2,623.0
Pension Plans with ABO in Excess of Plan Assets:
ABO	2,608.6	2,951.0
Fair value of plan assets	2,467.5	2,623.0
International
Pension Plans with PBO in Excess of Plan Assets:
PBO	452.6	465.7
Fair value of Plan assets	276.8	243.1
Pension Plans with ABO in Excess of Plan Assets:
ABO	357.9	365.6
Fair value of plan assets	$ 228.2	$ 197.1

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 50
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-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920

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