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, 2021 USD ($)
Estimated Benefit Payments Excluding Medicare Part D Subsidy
2020	$ 1.2
2021	1.2
2022	1.2
2023	1.1
2024	1.0
2027-2031	3.8
Expected Medicare Part D Subsidy
2020	0.0
2021	0.0
2022	0.0
2023	0.0
2024	0.0
2027-2031	0.0
Net Estimated Benefit Payments
2020	1.2
2021	1.2
2022	1.2
2023	1.1
2024	1.0
2027-2031	$ 3.8

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, after Year Five

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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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