Asset Retirement Obligations

6 Months Ended

Jun. 30, 2012

Asset Retirement Obligation Disclosure [Abstract]

The following table provides a summary of our asset retirement obligation activity during the six months ended June 30, 2012 and 2011.



	For the six months ended June 30,
	2012			2011
Beginning balance	$	46,493		$	41,695
Liabilities incurred in current period	416			242
Liabilities settled in current period	(1,211		)	(550		)
Accretion expense	1,969			1,769
	47,667			43,156
Less current portion	2,900			690
	$	44,767		$	42,466

See Note 5 for additional information regarding fair value measurements.

- Definition

The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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