Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Summary Of Changes In Asset Retirement Obligations

The following table presents the changes in asset retirement obligations.

	Year Ended December 31,
	2020			2019
Asset retirement obligations as of beginning of period	$	398		$	484
Liabilities incurred		18			20
Liabilities settled and divested		(29	)		(66	)
Liabilities reclassified as held for sale		(42	)		—
Revision of estimated obligation		4			(61	)
Accretion expense on discounted obligation		20			21
Asset retirement obligations as of end of period		369			398
Less current portion		11			18
Asset retirement obligations, long-term	$	358		$	380