Retirement Benefits - Schedule of Significant Assumptions Used in Determining Net Periodic Benefit Cost (Income) and Benefit Obligations (Details)	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
U.S. Plans \| Pension Benefits
Net periodic benefit cost assumptions
Discount rate	2.90%	3.30%	4.35%
Expected return on plan assets	7.25%	7.50%	7.50%
Compensation increase rate	3.40%	3.40%	3.50%
U.S. Plans \| Other Postretirement Benefits
Net periodic benefit cost assumptions
Discount rate	2.15%	2.90%	4.15%
Expected return on plan assets	0.00%	0.00%	0.00%
Compensation increase rate	0.00%	0.00%	0.00%
Non-U.S. Plans \| Pension Benefits
Net periodic benefit cost assumptions
Discount rate	1.56%	1.60%	2.48%
Expected return on plan assets	4.68%	5.11%	5.22%
Compensation increase rate	2.90%	3.06%	3.02%
Non-U.S. Plans \| Other Postretirement Benefits
Net periodic benefit cost assumptions
Discount rate	2.20%	2.65%	3.30%
Expected return on plan assets	0.00%	0.00%	0.00%
Compensation increase rate	0.00%	0.00%	0.00%

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2919-114920

+ Details

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- Definition

Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

+ References

+ Details

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- References

No definition available.

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