Asset retirement obligations (“ARO”)

12 Months Ended

Dec. 31, 2014

Asset Retirement Obligation Disclosure [Abstract]

Asset retirement obligations ("ARO")

Our asset retirement obligations consist primarily of costs associated with the disposal of spent pot liner used in the reduction cells of our domestic facilities.

The reconciliation of the changes in the asset retirement obligations is presented below:



	Year ended December 31,
	2014			2013
Beginning balance, ARO liability	$	27,113		$	16,124
Additional ARO liability incurred	2,548			1,730
ARO liabilities settled	(4,731		)	(2,580		)
Accretion expense	1,517			1,733
Additional ARO liability from Sebree acquisition	—			10,106
Additional ARO liability from Mt. Holly acquisition	10,503			—
Ending balance, ARO liability	$	36,950		$	27,113

Certain conditional AROs related to the disposal costs of fixed assets at our primary aluminum facilities have not been recorded because they have an indeterminate settlement date. These conditional AROs will be initially recognized in the period in which sufficient information exists to estimate their fair value.