ASSET RETIREMENT OBLIGATIONS Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Change in Asset Retirement Obligation

The following table is a reconciliation of the carrying amount of the ARO liability for the periods presented. Changes in assumptions regarding the timing, amount, and probabilities associated with the expected cash flows, as well as the difference in actual versus estimated costs, may result in a change in the amount of the liability recognized.

	Years Ended December 31,
	2020		2019		2018
Beginning balance	$	35	$	26	$	57
Revisions	—		9		(33)
Settled	—		(2)		(1)
Accretion expense	2		2		3
Ending balance	$	37	$	35	$	26