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Pension Benefits and Other Postretirement Benefits
 3 Months Ended
Mar. 31, 2024
Retirement Benefits [Abstract]  
Pension Benefits and Other Postretirement Benefits Pension Benefits and Other Postretirement Benefits
Pension and Other Postretirement Benefit Plans
As of March 31, 2024, we had one qualified noncontributory defined benefit pension plan, the Union Plan, which was frozen and ceased accruing benefits in 2013. Additionally, we sponsor other postretirement benefit plans, including multiple fully insured or self-funded medical plans and life insurance plans for certain retirees. The measurement date for all plans is December 31st for each respective plan year.
Components of Net Periodic Benefit Cost (Credit)
The components of net periodic benefit (credit) cost were as follows:
Pension Benefits
Three Months Ended
March 31,
(Dollars in millions)20242023
Interest cost0.2 0.3 
Expected return of plan assets(0.3)(0.4)
Amortization of net loss (gain)0.1 0.1 
Net periodic benefit cost (credit)$— $— 
Employer Contributions
There were no required or voluntary contributions made to the Union Plan for each of the three months ended March 31, 2024 and 2023. Additionally, we are not required to make additional contributions to the Union Plan for the remainder of 2024.
As there is no funding requirement for the other postretirement benefit plans, we funded these benefit payments as incurred, which were immaterial for each of the three months ended March 31, 2024 and 2023, using cash from operations.