Asset Retirement Obligations

6 Months Ended

Jun. 30, 2019

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligations Roll Forward

Asset Retirement Obligations

The Company's asset retirement obligations are principally for costs to close its surface mines and reclaim the land it has disturbed as a result of its normal mining activities as well as for costs to dismantle certain mining equipment at the end of the life of the mine. A reconciliation of the Company's beginning and ending aggregate carrying amount of the asset retirement obligations are as follows:

	Asset Retirement Obligations
Balance at December 31, 2018	$	37,703
Liabilities settled during the period	(3,587		)
Accretion expense	1,258
Revision of estimated cash flows	(2,986		)
Balance at June 30, 2019	$	32,388

During the second quarter of 2019, the Company transferred the mine permits for certain Centennial mines to an unrelated third party.  As a result of these transfers, the Company was relieved of the associated mine reclamation obligations and recorded a $5.4 million reduction to Centennial's asset retirement obligation, $2.4 million of which is reflected as "Liabilities settled during the current period" and $3.0 million of which is reflected as "Revisions in estimated cash flows" in the table above.  As part of these transactions, the Company transferred a $3.4 million escrow account and paid $2.4 million of cash, resulting in a net loss on the transactions of $0.4 million recognized within cost of sales in the Unaudited Condensed Consolidated Statement of Operations.