Pension Plan and Retirement Benefits - Expected benefit payments (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Defined Benefit Pension Plan
Expected benefit payments
2024	$ 16,001
2025	16,308
2026	16,623
2027	16,953
2028	17,002
2029-2033 (in total)	86,225
Defined Benefit Other Postretirement Benefit Plan
Expected benefit payments
2024	3,988
2025	4,021
2026	4,124
2027	4,063
2028	4,101
2029-2033 (in total)	$ 21,333

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- Definition

Amount of benefit for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following current fiscal year.

+ References

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

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Amount of benefit for defined benefit plan expected to be paid in next fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in fifth fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in fourth fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in third fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in second fiscal year following current fiscal year.

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