Supplemental Information To Statements Of Cash Flows (Schedule Of Supplemental Information To Statements Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Changes in assets and liabilities, net:
Accounts receivable	$ 238	$ (29)
Income tax receivable	(113)
Other current assets	(38)	9
Other long-term assets	(24)	(8)
Accounts payable	42	(51)
Revenues and royalties payable	(113)	46
Other current liabilities	(81)	(23)
Other long-term liabilities	33	(5)
Total	(56)	(61)
Supplementary cash flow data - total operations:
Interest paid (net of capitalized interest)	64	53
Income taxes paid	$ 151	$ 6