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Commitments and Contingencies (Tables)
 12 Months Ended
Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]  
Reconciliation of Undiscounted Amount to Recorded Balance The table below summaries our environmental liability accruals (in millions):
December 31,
20242023
Discounted environmental liabilities$33.6 $36.0 
Undiscounted environmental liabilities3.6 77.9 
  Total accrued environmental liabilities$37.2 $113.9 
Schedule of Estimated Future Payments of Environmental Obligations
As of December 31, 2024, the estimated future payments of environmental obligations for which discounts have been applied are as follows (in millions):
2025$1.5 
20261.6 
20271.6 
20281.6 
20291.6 
Thereafter29.6 
Discounted environmental liabilities, gross37.5 
Less: Discount applied3.9 
Discounted environmental liabilities$33.6 
Schedule of Asset Retirement Obligations
The reconciliation of the beginning and ending carrying amounts of asset retirement obligations is as follows (in millions):
December 31,
20242023
Beginning balance$36.4 $35.1 
Liabilities acquired4.9 — 
Revision in estimated cash flows(18.1)— 
Accretion expense1.5 1.3 
Ending balance$24.7 $36.4