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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-8

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Pension Plan and Retirement Benefits - Investment Strategy (Details)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Pension Plans Defined Benefit Us [Member]
Asset allocation
Plan's return on assets assumption (as a percent)	6.88%	5.25%	7.25%
Pension Plans Defined Benefit Us [Member] \| Equity
Asset allocation
Target plan asset allocation (as a percent)	11.00%
Pension Plans Defined Benefit Us [Member] \| Fixed Income
Asset allocation
Target plan asset allocation (as a percent)	89.00%
Pension Plans Defined Benefit Non Us [Member]
Asset allocation
Plan's return on assets assumption (as a percent)	5.50%	3.00%	2.00%