Accounts Receivable (Schedule Of Components Of Accounts Receivable) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Joint interest billings	$ 127	$ 57
Other	54	25
Gross accounts receivable	1,104	612
Allowance for doubtful accounts	(15)	(11)
Net accounts receivable	1,089	601
Oil, Gas and NGL Sales [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	742	335
Marketing and Midstream Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 181	$ 195