Retirement Benefits (Benefit Liability Exceeds Value of Plan Assets) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
U.S.
Pension Plans with PBO in Excess of Plan Assets:
PBO	$ 3,116.7	$ 3,477.7
Fair value of Plan assets	2,623.0	2,705.3
Pension Plans with ABO in Excess of Plan Assets:
ABO	2,951.0	3,242.5
Fair value of plan assets	2,623.0	2,705.3
International
Pension Plans with PBO in Excess of Plan Assets:
PBO	465.7	1,849.6
Fair value of Plan assets	243.1	1,411.1
Pension Plans with ABO in Excess of Plan Assets:
ABO	365.6	1,673.6
Fair value of plan assets	$ 197.1	$ 1,370.1

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920

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- Definition

Fair value of plan assets for defined benefit pension plan with accumulated benefit obligation in excess of plan assets.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920

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- Definition

Fair value of plan assets for defined benefit plan with benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920

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