Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2012

Asset Retirement Obligation Disclosure [Abstract]

Schedule of changes in the carrying amounts of the ARO

The changes in the carrying amount of the ARO during the six months ended June 30, 2012, and June 30, 2011, are as follows:

	For the six months ended
	June 30,
	2012			2011
Beginning balance	$	33,880		$	44,952
Accretion expense	1,408			3,116
Additions and changes in estimates	—			3,748
Cost of reclamation work performed	(4,422		)	(11,828		)
Balance at June 30	$	30,866		$	39,988
Current portion	$	8,256		$	15,459
Long term portion	$	22,610		$	24,529