Asset Retirement Obligations

12 Months Ended

Dec. 31, 2022

Asset Retirement Obligation Disclosure [Abstract]

Reconciliations of the Company’s asset retirement obligations are as follows:


	December 31,
	2022		2021
	(Dollars in millions)
Balance at beginning of period	$	719.8	$	728.2

Liabilities settled or disposed	(51.7)		(72.4)
Accretion expense	56.2		54.9
Revisions to estimates	25.7		9.1
Balance at end of period	$	750.0	$	719.8
Less: Current portion (included in “Accounts payable and accrued expenses”)	84.2		65.0
Noncurrent obligation (included in “Asset retirement obligations”)	$	665.8	$	654.8
Balance at end of period — active locations	$	557.9	$	511.8
Balance at end of period — closed or inactive locations	$	192.1	$	208.0

As of December 31, 2022 and 2021, the Company had $1,250.1 million and $1,294.7 million, respectively, in surety bonds outstanding to secure reclamation obligations. Additionally, the Company had $437.8 million and $323.0 million, respectively, of letters of credit in support of reclamation obligations as of December 31, 2022 and 2021. See Note 20. “Financial Instruments, Guarantees With Off-Balance-Sheet Risk and Other Guarantees” for a discussion of cash collateral supporting these reclamation bonding requirements.