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Asset Retirement Obligations (Tables)
12 Months Ended
Dec. 31, 2024
Asset Retirement Obligation Disclosure [Abstract]  
Reconciliations of the Company's ARO liability
Reconciliations of the Company’s asset retirement obligations are as follows:
 December 31,
 20242023
 (Dollars in millions)
Balance at beginning of period$702.8 $750.0 
Liabilities settled(51.7)(60.4)
Accretion expense51.4 61.3 
Revisions to estimates21.2 (48.1)
Balance at end of period$723.7 $702.8 
Less: Current portion (included in “Accounts payable and accrued expenses”)55.9 54.2 
Noncurrent obligation (included in “Asset retirement obligations, less current portion”)$667.8 $648.6 
Balance at end of period — active locations$507.9 $541.3 
Balance at end of period — closed or inactive locations$215.8 $161.5