Credit Losses (Tables)

6 Months Ended

Jun. 30, 2021

Credit Loss [Abstract]

Changes in Allowance For Doubtful Account Balance

Changes in the allowance for doubtful accounts balance were as follows:    

(In millions)	June 30, 2021		December 31, 2020
Beginning balance as of January 1	$	22	$	11
Cumulative-effect adjustment	—		12
Current period provision(a)	(2)		22
Current period write offs	(1)		(13)
Recoveries of amounts previously reserved	—		(10)
Ending balance	$	19	$	22

(a)As of December 31, 2020, the current period provision consisted of $10 million in joint interest receivables and $12 million in trade receivables.