Pension Plan and Retirement Benefits - Expected benefit payments (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Defined Benefit Pension Plans
Expected benefit payments
2019	$ 14,226
2020	14,768
2021	15,251
2022	15,790
2023	16,243
2024-2028 (in total)	85,854
Postretirement Health Care Benefits
Expected benefit payments
2019	5,000
2020	5,000
2021	5,000
2022	5,000
2023	5,000
2024-2028 (in total)	$ 25,000

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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

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

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

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

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

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