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Asset retirement obligations (“ARO”)
 6 Months Ended
Jun. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]  
Asset retirement obligations (“ARO”)
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:
 
Six months ended June 30, 2013
Year ended December 31, 2012
Beginning balance, ARO liability
$
16,124

$
15,171

Additional ARO liability incurred
764

1,166

ARO liabilities settled
(796
)
(1,380
)
Accretion expense
673

1,167

Additional ARO liability from Sebree acquisition
10,591

—

Ending balance, ARO liability
$
27,356

$
16,124


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.