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Asset Retirement Obligations (ARO) (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Asset Retirement Obligation Roll Forward      
Balance at beginning of period $ 49.1 $ 46.1 $ 46.1
Accretion expense 0.9 $ 0.8 3.2
Settlements of liabilities (0.7)   (3.1)
Liabilities incurred 0.0   2.9
Balance at end of period $ 49.3   $ 49.1