Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2019

Asset Retirement Obligation Disclosure [Abstract]

Changes to Asset Retirement Obligations

The following table describes changes to our asset retirement obligations:

	2019			2018
	(In millions)
Balance at January 1	$	857		$	801
Liabilities incurred		72			68
Liabilities settled or disposed of		(75	)		(46	)
Accretion expense		40			37
Revisions of estimated liabilities		129			1
Foreign currency remeasurement		1			(4	)
Balance at December 31	$	1,024		$	857
Total Asset Retirement Obligations at December 31:
Current portion of asset retirement obligations	$	127		$	116
Long-term asset retirement obligations		897			741
Total at December 31	$	1,024		$	857