Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2011

Asset Retirement Obligations [Abstract]

Change to asset retirement obligations

	September 30,			December 31,
	2011			2010
	(Millions of dollars)
Asset retirement obligations at beginning of period	$	1,358		$	1,297
Liabilities incurred		25			255
Liabilities settled or disposed of		(75	)		(282	)
Accretion expense		70			78
Revisions of estimates		757			(6	)
Foreign currency translation		(10	)		16
Asset retirement obligations at end of period		2,125			1,358
Less: current obligations		244			155
Long-term obligations at end of period	$	1,881		$	1,203