Asset Retirement Obligations

9 Months Ended

Sep. 30, 2014

Asset Retirement Obligation Disclosure [Abstract]

8. Asset Retirement Obligations

The following table describes changes to the Corporation’s asset retirement obligations for the nine months ended September 30, 2014 and year ended December 31, 2013:

	September 30,			December 31,
	2014			2013
	(In millions)
Asset retirement obligations at beginning of period	$	2,772		$	2,661
Liabilities incurred		63			42
Liabilities settled or disposed of		(345	)		(576	)
Accretion expense		99			129
Revisions of estimated liabilities		275			573
Foreign currency translation		(51	)		(57	)
Asset retirement obligations at end of period		2,813			2,772
Less: Current obligations		500			523
Long-term obligations at end of period	$	2,313		$	2,249

The revisions of estimated liabilities in 2014 and 2013 primarily reflect increases in estimated abandonment obligations resulting from changes in the expected scope of operations and changes in estimated service and equipment costs.