Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2021

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,
	2021		2020
	(Dollars in millions)
Balance at beginning of period	$	728.2	$	752.3
Liabilities settled or disposed	(72.4)		(38.4)
Accretion expense	54.9		56.0
Revisions to estimates	9.1		(41.7)
Balance at end of period	$	719.8	$	728.2
Less: Current portion (included in “Accounts payable and accrued expenses”)	65.0		77.7
Noncurrent obligation (included in “Asset retirement obligations”)	$	654.8	$	650.5
Balance at end of period — active locations	$	511.8	$	471.8
Balance at end of period — closed or inactive locations	$	208.0	$	256.4