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ASSET RETIREMENT OBLIGATIONS (Tables)
 9 Months Ended
Sep. 30, 2024
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Asset Retirement Obligations Operating Costs
ARO operating costs related to accretion of the liabilities and depreciation of the assets are as follows:
Three Months Ended
September 30		Nine Months Ended
September 30
in millions2024202320242023
Accretion$3.7 $3.5 $10.8 $10.3 
Depreciation3.2 2.2 8.4 6.6 
Total ARO operating costs$6.9 $5.7 $19.2 $16.9 
Schedule of Reconciliations of Asset Retirement Obligations
Reconciliations of the carrying amounts of our AROs are as follows:
Three Months Ended
September 30		Nine Months Ended
September 30
in millions2024202320242023
ARO balance at beginning of period$334.1 $311.6 $324.1 $311.3 
Liabilities incurred0.0 0.0 0.8 0.0 
Liabilities settled(3.5)(1.9)(8.3)(8.4)
Accretion expense3.7 3.5 10.8 10.3 
Revisions, net12.2 2.3 19.1 2.3 
ARO balance at end of period$346.5 $315.5 $346.5 $315.5