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Asset Retirement Obligations - Changes to Asset Retirement Obligation (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset retirement obligation at beginning of period $ 30.2 $ 29.4
Accretion expense 1.6 1.3
Liabilities Incurred 0.1 0.0
Payments (0.4) (0.3)
Revisions in estimated cash flows (0.1) (0.2)
Asset retirement obligation at end of period $ 31.4 $ 30.2