Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Changes to Asset Retirement Obligations

The following table describes changes to our asset retirement obligations:

	2020		2019
	(In millions)
Balance at January 1	$	1,024	$	857
Liabilities incurred	36		72
Liabilities settled or disposed of	(161)		(75)
Accretion expense	46		40
Revisions of estimated liabilities	52		129
Foreign currency remeasurement	2		1
Balance at December 31	$	999	$	1,024
Total Asset Retirement Obligations at December 31:
Current portion of asset retirement obligations	$	105	$	127
Long-term asset retirement obligations	894		897
Total at December 31	$	999	$	1,024