Postretirement Benefits Other Than Pensions - Benefit Payments Net of Expected Medicare Part D Subsidy (Details) - Other Postretirement Benefit Plan, Defined Benefit $ in Millions	Dec. 31, 2023 USD ($)
Estimated Benefit Payments Excluding Medicare Part D Subsidy
2020	$ 0.9
2021	0.9
2022	0.9
2023	0.8
2024	0.7
2029-2032	3.0
Expected Medicare Part D Subsidy
2020	0.0
2021	0.0
2022	0.0
2023	0.0
2024	0.0
2029-2032	0.0
Net Estimated Benefit Payments
2020	0.9
2021	0.9
2022	0.9
2023	0.8
2024	0.7
2029-2032	$ 3.0

Defined Benefit Plan, Expected Future Benefit Payments Excluding Prescription Drug Subsidy Receipts, Next Twelve Months

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Defined Benefit Plan, Expected Future Benefit Payments Excluding Prescription Drug Subsidy Receipts, Year Three

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Defined Benefit Plan, Expected Future Benefit Payments Excluding Prescription Drug Subsidy Receipts, after Year Five

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

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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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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Amount of prescription drug subsidy receipt expected after fifth fiscal year following current fiscal year.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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