Asset Retirement Obligations

12 Months Ended

Dec. 31, 2012

10. ASSET RETIREMENT OBLIGATIONS

The changes in the carrying value of the Company's asset retirement obligations for the years ended December 31, 2012 and 2011 are as follows (in thousands):


		2012		2011 (1)
Beginning balance as of January 1,		$	344,180	$	341,838
Additions			59,847		47,426
Revisions in estimated timing and cash flows, net of settlements			6,641		(70,755)
Accretion expense			25,056		25,671

Balance as of December 31,		$	435,724	$	344,180


(1)	December 31, 2011 balances have been revised to reflect purchase accounting measurement period adjustments.

As of December 31, 2012, the estimated undiscounted future cash outlay for asset retirement obligations was approximately $1.5 billion.

- 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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